drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <linux/flex_array.h>
  58 #include <trace/events/block.h>
  59
  60 #include "md.h"
  61 #include "raid5.h"
  62 #include "raid0.h"
  63 #include "bitmap.h"
  64
  65 #define cpu_to_group(cpu) cpu_to_node(cpu)
  66 #define ANY_GROUP NUMA_NO_NODE
  67
  68 static bool devices_handle_discard_safely = false;
  69 module_param(devices_handle_discard_safely, bool, 0644);
  70 MODULE_PARM_DESC(devices_handle_discard_safely,
  71                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  72 static struct workqueue_struct *raid5_wq;
  73 /*
  74  * Stripe cache
  75  */
  76
  77 #define NR_STRIPES              256
  78 #define STRIPE_SIZE             PAGE_SIZE
  79 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  80 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  81 #define IO_THRESHOLD            1
  82 #define BYPASS_THRESHOLD        1
  83 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  84 #define HASH_MASK               (NR_HASH - 1)
  85 #define MAX_STRIPE_BATCH        8
  86
  87 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  88 {
  89         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  90         return &conf->stripe_hashtbl[hash];
  91 }
  92
  93 static inline int stripe_hash_locks_hash(sector_t sect)
  94 {
  95         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  96 }
  97
  98 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  99 {
 100         spin_lock_irq(conf->hash_locks + hash);
 101         spin_lock(&conf->device_lock);
 102 }
 103
 104 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
 105 {
 106         spin_unlock(&conf->device_lock);
 107         spin_unlock_irq(conf->hash_locks + hash);
 108 }
 109
 110 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 111 {
 112         int i;
 113         spin_lock_irq(conf->hash_locks);
 114         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 115                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 116         spin_lock(&conf->device_lock);
 117 }
 118
 119 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 120 {
 121         int i;
 122         spin_unlock(&conf->device_lock);
 123         for (i = NR_STRIPE_HASH_LOCKS - 1; i; i--)
 124                 spin_unlock(conf->hash_locks + i);
 125         spin_unlock_irq(conf->hash_locks);
 126 }
 127
 128 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
 129  * order without overlap.  There may be several bio's per stripe+device, and
 130  * a bio could span several devices.
 131  * When walking this list for a particular stripe+device, we must never proceed
 132  * beyond a bio that extends past this device, as the next bio might no longer
 133  * be valid.
 134  * This function is used to determine the 'next' bio in the list, given the sector
 135  * of the current stripe+device
 136  */
 137 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
 138 {
 139         int sectors = bio_sectors(bio);
 140         if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
 141                 return bio->bi_next;
 142         else
 143                 return NULL;
 144 }
 145
 146 /*
 147  * We maintain a biased count of active stripes in the bottom 16 bits of
 148  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 149  */
 150 static inline int raid5_bi_processed_stripes(struct bio *bio)
 151 {
 152         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 153         return (atomic_read(segments) >> 16) & 0xffff;
 154 }
 155
 156 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 157 {
 158         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 159         return atomic_sub_return(1, segments) & 0xffff;
 160 }
 161
 162 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 163 {
 164         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 165         atomic_inc(segments);
 166 }
 167
 168 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 169         unsigned int cnt)
 170 {
 171         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 172         int old, new;
 173
 174         do {
 175                 old = atomic_read(segments);
 176                 new = (old & 0xffff) | (cnt << 16);
 177         } while (atomic_cmpxchg(segments, old, new) != old);
 178 }
 179
 180 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 181 {
 182         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 183         atomic_set(segments, cnt);
 184 }
 185
 186 /* Find first data disk in a raid6 stripe */
 187 static inline int raid6_d0(struct stripe_head *sh)
 188 {
 189         if (sh->ddf_layout)
 190                 /* ddf always start from first device */
 191                 return 0;
 192         /* md starts just after Q block */
 193         if (sh->qd_idx == sh->disks - 1)
 194                 return 0;
 195         else
 196                 return sh->qd_idx + 1;
 197 }
 198 static inline int raid6_next_disk(int disk, int raid_disks)
 199 {
 200         disk++;
 201         return (disk < raid_disks) ? disk : 0;
 202 }
 203
 204 /* When walking through the disks in a raid5, starting at raid6_d0,
 205  * We need to map each disk to a 'slot', where the data disks are slot
 206  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 207  * is raid_disks-1.  This help does that mapping.
 208  */
 209 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 210                              int *count, int syndrome_disks)
 211 {
 212         int slot = *count;
 213
 214         if (sh->ddf_layout)
 215                 (*count)++;
 216         if (idx == sh->pd_idx)
 217                 return syndrome_disks;
 218         if (idx == sh->qd_idx)
 219                 return syndrome_disks + 1;
 220         if (!sh->ddf_layout)
 221                 (*count)++;
 222         return slot;
 223 }
 224
 225 static void return_io(struct bio_list *return_bi)
 226 {
 227         struct bio *bi;
 228         while ((bi = bio_list_pop(return_bi)) != NULL) {
 229                 bi->bi_iter.bi_size = 0;
 230                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 231                                          bi, 0);
 232                 bio_endio(bi);
 233         }
 234 }
 235
 236 static void print_raid5_conf (struct r5conf *conf);
 237
 238 static int stripe_operations_active(struct stripe_head *sh)
 239 {
 240         return sh->check_state || sh->reconstruct_state ||
 241                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 242                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 243 }
 244
 245 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 246 {
 247         struct r5conf *conf = sh->raid_conf;
 248         struct r5worker_group *group;
 249         int thread_cnt;
 250         int i, cpu = sh->cpu;
 251
 252         if (!cpu_online(cpu)) {
 253                 cpu = cpumask_any(cpu_online_mask);
 254                 sh->cpu = cpu;
 255         }
 256
 257         if (list_empty(&sh->lru)) {
 258                 struct r5worker_group *group;
 259                 group = conf->worker_groups + cpu_to_group(cpu);
 260                 list_add_tail(&sh->lru, &group->handle_list);
 261                 group->stripes_cnt++;
 262                 sh->group = group;
 263         }
 264
 265         if (conf->worker_cnt_per_group == 0) {
 266                 md_wakeup_thread(conf->mddev->thread);
 267                 return;
 268         }
 269
 270         group = conf->worker_groups + cpu_to_group(sh->cpu);
 271
 272         group->workers[0].working = true;
 273         /* at least one worker should run to avoid race */
 274         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 275
 276         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 277         /* wakeup more workers */
 278         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 279                 if (group->workers[i].working == false) {
 280                         group->workers[i].working = true;
 281                         queue_work_on(sh->cpu, raid5_wq,
 282                                       &group->workers[i].work);
 283                         thread_cnt--;
 284                 }
 285         }
 286 }
 287
 288 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 289                               struct list_head *temp_inactive_list)
 290 {
 291         BUG_ON(!list_empty(&sh->lru));
 292         BUG_ON(atomic_read(&conf->active_stripes)==0);
 293         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 294                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 295                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 296                         list_add_tail(&sh->lru, &conf->delayed_list);
 297                 else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 298                            sh->bm_seq - conf->seq_write > 0)
 299                         list_add_tail(&sh->lru, &conf->bitmap_list);
 300                 else {
 301                         clear_bit(STRIPE_DELAYED, &sh->state);
 302                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 303                         if (conf->worker_cnt_per_group == 0) {
 304                                 list_add_tail(&sh->lru, &conf->handle_list);
 305                         } else {
 306                                 raid5_wakeup_stripe_thread(sh);
 307                                 return;
 308                         }
 309                 }
 310                 md_wakeup_thread(conf->mddev->thread);
 311         } else {
 312                 BUG_ON(stripe_operations_active(sh));
 313                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 314                         if (atomic_dec_return(&conf->preread_active_stripes)
 315                             < IO_THRESHOLD)
 316                                 md_wakeup_thread(conf->mddev->thread);
 317                 atomic_dec(&conf->active_stripes);
 318                 if (!test_bit(STRIPE_EXPANDING, &sh->state))
 319                         list_add_tail(&sh->lru, temp_inactive_list);
 320         }
 321 }
 322
 323 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 324                              struct list_head *temp_inactive_list)
 325 {
 326         if (atomic_dec_and_test(&sh->count))
 327                 do_release_stripe(conf, sh, temp_inactive_list);
 328 }
 329
 330 /*
 331  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 332  *
 333  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 334  * given time. Adding stripes only takes device lock, while deleting stripes
 335  * only takes hash lock.
 336  */
 337 static void release_inactive_stripe_list(struct r5conf *conf,
 338                                          struct list_head *temp_inactive_list,
 339                                          int hash)
 340 {
 341         int size;
 342         bool do_wakeup = false;
 343         unsigned long flags;
 344
 345         if (hash == NR_STRIPE_HASH_LOCKS) {
 346                 size = NR_STRIPE_HASH_LOCKS;
 347                 hash = NR_STRIPE_HASH_LOCKS - 1;
 348         } else
 349                 size = 1;
 350         while (size) {
 351                 struct list_head *list = &temp_inactive_list[size - 1];
 352
 353                 /*
 354                  * We don't hold any lock here yet, raid5_get_active_stripe() might
 355                  * remove stripes from the list
 356                  */
 357                 if (!list_empty_careful(list)) {
 358                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 359                         if (list_empty(conf->inactive_list + hash) &&
 360                             !list_empty(list))
 361                                 atomic_dec(&conf->empty_inactive_list_nr);
 362                         list_splice_tail_init(list, conf->inactive_list + hash);
 363                         do_wakeup = true;
 364                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 365                 }
 366                 size--;
 367                 hash--;
 368         }
 369
 370         if (do_wakeup) {
 371                 wake_up(&conf->wait_for_stripe);
 372                 if (atomic_read(&conf->active_stripes) == 0)
 373                         wake_up(&conf->wait_for_quiescent);
 374                 if (conf->retry_read_aligned)
 375                         md_wakeup_thread(conf->mddev->thread);
 376         }
 377 }
 378
 379 /* should hold conf->device_lock already */
 380 static int release_stripe_list(struct r5conf *conf,
 381                                struct list_head *temp_inactive_list)
 382 {
 383         struct stripe_head *sh;
 384         int count = 0;
 385         struct llist_node *head;
 386
 387         head = llist_del_all(&conf->released_stripes);
 388         head = llist_reverse_order(head);
 389         while (head) {
 390                 int hash;
 391
 392                 sh = llist_entry(head, struct stripe_head, release_list);
 393                 head = llist_next(head);
 394                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 395                 smp_mb();
 396                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 397                 /*
 398                  * Don't worry the bit is set here, because if the bit is set
 399                  * again, the count is always > 1. This is true for
 400                  * STRIPE_ON_UNPLUG_LIST bit too.
 401                  */
 402                 hash = sh->hash_lock_index;
 403                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 404                 count++;
 405         }
 406
 407         return count;
 408 }
 409
 410 void raid5_release_stripe(struct stripe_head *sh)
 411 {
 412         struct r5conf *conf = sh->raid_conf;
 413         unsigned long flags;
 414         struct list_head list;
 415         int hash;
 416         bool wakeup;
 417
 418         /* Avoid release_list until the last reference.
 419          */
 420         if (atomic_add_unless(&sh->count, -1, 1))
 421                 return;
 422
 423         if (unlikely(!conf->mddev->thread) ||
 424                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 425                 goto slow_path;
 426         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 427         if (wakeup)
 428                 md_wakeup_thread(conf->mddev->thread);
 429         return;
 430 slow_path:
 431         local_irq_save(flags);
 432         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 433         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 434                 INIT_LIST_HEAD(&list);
 435                 hash = sh->hash_lock_index;
 436                 do_release_stripe(conf, sh, &list);
 437                 spin_unlock(&conf->device_lock);
 438                 release_inactive_stripe_list(conf, &list, hash);
 439         }
 440         local_irq_restore(flags);
 441 }
 442
 443 static inline void remove_hash(struct stripe_head *sh)
 444 {
 445         pr_debug("remove_hash(), stripe %llu\n",
 446                 (unsigned long long)sh->sector);
 447
 448         hlist_del_init(&sh->hash);
 449 }
 450
 451 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 452 {
 453         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 454
 455         pr_debug("insert_hash(), stripe %llu\n",
 456                 (unsigned long long)sh->sector);
 457
 458         hlist_add_head(&sh->hash, hp);
 459 }
 460
 461 /* find an idle stripe, make sure it is unhashed, and return it. */
 462 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 463 {
 464         struct stripe_head *sh = NULL;
 465         struct list_head *first;
 466
 467         if (list_empty(conf->inactive_list + hash))
 468                 goto out;
 469         first = (conf->inactive_list + hash)->next;
 470         sh = list_entry(first, struct stripe_head, lru);
 471         list_del_init(first);
 472         remove_hash(sh);
 473         atomic_inc(&conf->active_stripes);
 474         BUG_ON(hash != sh->hash_lock_index);
 475         if (list_empty(conf->inactive_list + hash))
 476                 atomic_inc(&conf->empty_inactive_list_nr);
 477 out:
 478         return sh;
 479 }
 480
 481 static void shrink_buffers(struct stripe_head *sh)
 482 {
 483         struct page *p;
 484         int i;
 485         int num = sh->raid_conf->pool_size;
 486
 487         for (i = 0; i < num ; i++) {
 488                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 489                 p = sh->dev[i].page;
 490                 if (!p)
 491                         continue;
 492                 sh->dev[i].page = NULL;
 493                 put_page(p);
 494         }
 495 }
 496
 497 static int grow_buffers(struct stripe_head *sh, gfp_t gfp)
 498 {
 499         int i;
 500         int num = sh->raid_conf->pool_size;
 501
 502         for (i = 0; i < num; i++) {
 503                 struct page *page;
 504
 505                 if (!(page = alloc_page(gfp))) {
 506                         return 1;
 507                 }
 508                 sh->dev[i].page = page;
 509                 sh->dev[i].orig_page = page;
 510         }
 511         return 0;
 512 }
 513
 514 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 515 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 516                             struct stripe_head *sh);
 517
 518 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 519 {
 520         struct r5conf *conf = sh->raid_conf;
 521         int i, seq;
 522
 523         BUG_ON(atomic_read(&sh->count) != 0);
 524         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 525         BUG_ON(stripe_operations_active(sh));
 526         BUG_ON(sh->batch_head);
 527
 528         pr_debug("init_stripe called, stripe %llu\n",
 529                 (unsigned long long)sector);
 530 retry:
 531         seq = read_seqcount_begin(&conf->gen_lock);
 532         sh->generation = conf->generation - previous;
 533         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 534         sh->sector = sector;
 535         stripe_set_idx(sector, conf, previous, sh);
 536         sh->state = 0;
 537
 538         for (i = sh->disks; i--; ) {
 539                 struct r5dev *dev = &sh->dev[i];
 540
 541                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 542                     test_bit(R5_LOCKED, &dev->flags)) {
 543                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 544                                (unsigned long long)sh->sector, i, dev->toread,
 545                                dev->read, dev->towrite, dev->written,
 546                                test_bit(R5_LOCKED, &dev->flags));
 547                         WARN_ON(1);
 548                 }
 549                 dev->flags = 0;
 550                 raid5_build_block(sh, i, previous);
 551         }
 552         if (read_seqcount_retry(&conf->gen_lock, seq))
 553                 goto retry;
 554         sh->overwrite_disks = 0;
 555         insert_hash(conf, sh);
 556         sh->cpu = smp_processor_id();
 557         set_bit(STRIPE_BATCH_READY, &sh->state);
 558 }
 559
 560 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 561                                          short generation)
 562 {
 563         struct stripe_head *sh;
 564
 565         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 566         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 567                 if (sh->sector == sector && sh->generation == generation)
 568                         return sh;
 569         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 570         return NULL;
 571 }
 572
 573 /*
 574  * Need to check if array has failed when deciding whether to:
 575  *  - start an array
 576  *  - remove non-faulty devices
 577  *  - add a spare
 578  *  - allow a reshape
 579  * This determination is simple when no reshape is happening.
 580  * However if there is a reshape, we need to carefully check
 581  * both the before and after sections.
 582  * This is because some failed devices may only affect one
 583  * of the two sections, and some non-in_sync devices may
 584  * be insync in the section most affected by failed devices.
 585  */
 586 static int calc_degraded(struct r5conf *conf)
 587 {
 588         int degraded, degraded2;
 589         int i;
 590
 591         rcu_read_lock();
 592         degraded = 0;
 593         for (i = 0; i < conf->previous_raid_disks; i++) {
 594                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 595                 if (rdev && test_bit(Faulty, &rdev->flags))
 596                         rdev = rcu_dereference(conf->disks[i].replacement);
 597                 if (!rdev || test_bit(Faulty, &rdev->flags))
 598                         degraded++;
 599                 else if (test_bit(In_sync, &rdev->flags))
 600                         ;
 601                 else
 602                         /* not in-sync or faulty.
 603                          * If the reshape increases the number of devices,
 604                          * this is being recovered by the reshape, so
 605                          * this 'previous' section is not in_sync.
 606                          * If the number of devices is being reduced however,
 607                          * the device can only be part of the array if
 608                          * we are reverting a reshape, so this section will
 609                          * be in-sync.
 610                          */
 611                         if (conf->raid_disks >= conf->previous_raid_disks)
 612                                 degraded++;
 613         }
 614         rcu_read_unlock();
 615         if (conf->raid_disks == conf->previous_raid_disks)
 616                 return degraded;
 617         rcu_read_lock();
 618         degraded2 = 0;
 619         for (i = 0; i < conf->raid_disks; i++) {
 620                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 621                 if (rdev && test_bit(Faulty, &rdev->flags))
 622                         rdev = rcu_dereference(conf->disks[i].replacement);
 623                 if (!rdev || test_bit(Faulty, &rdev->flags))
 624                         degraded2++;
 625                 else if (test_bit(In_sync, &rdev->flags))
 626                         ;
 627                 else
 628                         /* not in-sync or faulty.
 629                          * If reshape increases the number of devices, this
 630                          * section has already been recovered, else it
 631                          * almost certainly hasn't.
 632                          */
 633                         if (conf->raid_disks <= conf->previous_raid_disks)
 634                                 degraded2++;
 635         }
 636         rcu_read_unlock();
 637         if (degraded2 > degraded)
 638                 return degraded2;
 639         return degraded;
 640 }
 641
 642 static int has_failed(struct r5conf *conf)
 643 {
 644         int degraded;
 645
 646         if (conf->mddev->reshape_position == MaxSector)
 647                 return conf->mddev->degraded > conf->max_degraded;
 648
 649         degraded = calc_degraded(conf);
 650         if (degraded > conf->max_degraded)
 651                 return 1;
 652         return 0;
 653 }
 654
 655 struct stripe_head *
 656 raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
 657                         int previous, int noblock, int noquiesce)
 658 {
 659         struct stripe_head *sh;
 660         int hash = stripe_hash_locks_hash(sector);
 661
 662         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 663
 664         spin_lock_irq(conf->hash_locks + hash);
 665
 666         do {
 667                 wait_event_lock_irq(conf->wait_for_quiescent,
 668                                     conf->quiesce == 0 || noquiesce,
 669                                     *(conf->hash_locks + hash));
 670                 sh = __find_stripe(conf, sector, conf->generation - previous);
 671                 if (!sh) {
 672                         if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
 673                                 sh = get_free_stripe(conf, hash);
 674                                 if (!sh && !test_bit(R5_DID_ALLOC,
 675                                                      &conf->cache_state))
 676                                         set_bit(R5_ALLOC_MORE,
 677                                                 &conf->cache_state);
 678                         }
 679                         if (noblock && sh == NULL)
 680                                 break;
 681                         if (!sh) {
 682                                 set_bit(R5_INACTIVE_BLOCKED,
 683                                         &conf->cache_state);
 684                                 wait_event_lock_irq(
 685                                         conf->wait_for_stripe,
 686                                         !list_empty(conf->inactive_list + hash) &&
 687                                         (atomic_read(&conf->active_stripes)
 688                                          < (conf->max_nr_stripes * 3 / 4)
 689                                          || !test_bit(R5_INACTIVE_BLOCKED,
 690                                                       &conf->cache_state)),
 691                                         *(conf->hash_locks + hash));
 692                                 clear_bit(R5_INACTIVE_BLOCKED,
 693                                           &conf->cache_state);
 694                         } else {
 695                                 init_stripe(sh, sector, previous);
 696                                 atomic_inc(&sh->count);
 697                         }
 698                 } else if (!atomic_inc_not_zero(&sh->count)) {
 699                         spin_lock(&conf->device_lock);
 700                         if (!atomic_read(&sh->count)) {
 701                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 702                                         atomic_inc(&conf->active_stripes);
 703                                 BUG_ON(list_empty(&sh->lru) &&
 704                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 705                                 list_del_init(&sh->lru);
 706                                 if (sh->group) {
 707                                         sh->group->stripes_cnt--;
 708                                         sh->group = NULL;
 709                                 }
 710                         }
 711                         atomic_inc(&sh->count);
 712                         spin_unlock(&conf->device_lock);
 713                 }
 714         } while (sh == NULL);
 715
 716         spin_unlock_irq(conf->hash_locks + hash);
 717         return sh;
 718 }
 719
 720 static bool is_full_stripe_write(struct stripe_head *sh)
 721 {
 722         BUG_ON(sh->overwrite_disks > (sh->disks - sh->raid_conf->max_degraded));
 723         return sh->overwrite_disks == (sh->disks - sh->raid_conf->max_degraded);
 724 }
 725
 726 static void lock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 727 {
 728         if (sh1 > sh2) {
 729                 spin_lock_irq(&sh2->stripe_lock);
 730                 spin_lock_nested(&sh1->stripe_lock, 1);
 731         } else {
 732                 spin_lock_irq(&sh1->stripe_lock);
 733                 spin_lock_nested(&sh2->stripe_lock, 1);
 734         }
 735 }
 736
 737 static void unlock_two_stripes(struct stripe_head *sh1, struct stripe_head *sh2)
 738 {
 739         spin_unlock(&sh1->stripe_lock);
 740         spin_unlock_irq(&sh2->stripe_lock);
 741 }
 742
 743 /* Only freshly new full stripe normal write stripe can be added to a batch list */
 744 static bool stripe_can_batch(struct stripe_head *sh)
 745 {
 746         struct r5conf *conf = sh->raid_conf;
 747
 748         if (conf->log)
 749                 return false;
 750         return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 751                 !test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
 752                 is_full_stripe_write(sh);
 753 }
 754
 755 /* we only do back search */
 756 static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh)
 757 {
 758         struct stripe_head *head;
 759         sector_t head_sector, tmp_sec;
 760         int hash;
 761         int dd_idx;
 762
 763         if (!stripe_can_batch(sh))
 764                 return;
 765         /* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
 766         tmp_sec = sh->sector;
 767         if (!sector_div(tmp_sec, conf->chunk_sectors))
 768                 return;
 769         head_sector = sh->sector - STRIPE_SECTORS;
 770
 771         hash = stripe_hash_locks_hash(head_sector);
 772         spin_lock_irq(conf->hash_locks + hash);
 773         head = __find_stripe(conf, head_sector, conf->generation);
 774         if (head && !atomic_inc_not_zero(&head->count)) {
 775                 spin_lock(&conf->device_lock);
 776                 if (!atomic_read(&head->count)) {
 777                         if (!test_bit(STRIPE_HANDLE, &head->state))
 778                                 atomic_inc(&conf->active_stripes);
 779                         BUG_ON(list_empty(&head->lru) &&
 780                                !test_bit(STRIPE_EXPANDING, &head->state));
 781                         list_del_init(&head->lru);
 782                         if (head->group) {
 783                                 head->group->stripes_cnt--;
 784                                 head->group = NULL;
 785                         }
 786                 }
 787                 atomic_inc(&head->count);
 788                 spin_unlock(&conf->device_lock);
 789         }
 790         spin_unlock_irq(conf->hash_locks + hash);
 791
 792         if (!head)
 793                 return;
 794         if (!stripe_can_batch(head))
 795                 goto out;
 796
 797         lock_two_stripes(head, sh);
 798         /* clear_batch_ready clear the flag */
 799         if (!stripe_can_batch(head) || !stripe_can_batch(sh))
 800                 goto unlock_out;
 801
 802         if (sh->batch_head)
 803                 goto unlock_out;
 804
 805         dd_idx = 0;
 806         while (dd_idx == sh->pd_idx || dd_idx == sh->qd_idx)
 807                 dd_idx++;
 808         if (head->dev[dd_idx].towrite->bi_rw != sh->dev[dd_idx].towrite->bi_rw)
 809                 goto unlock_out;
 810
 811         if (head->batch_head) {
 812                 spin_lock(&head->batch_head->batch_lock);
 813                 /* This batch list is already running */
 814                 if (!stripe_can_batch(head)) {
 815                         spin_unlock(&head->batch_head->batch_lock);
 816                         goto unlock_out;
 817                 }
 818                 /*
 819                  * We must assign batch_head of this stripe within the
 820                  * batch_lock, otherwise clear_batch_ready of batch head
 821                  * stripe could clear BATCH_READY bit of this stripe and
 822                  * this stripe->batch_head doesn't get assigned, which
 823                  * could confuse clear_batch_ready for this stripe
 824                  */
 825                 sh->batch_head = head->batch_head;
 826
 827                 /*
 828                  * at this point, head's BATCH_READY could be cleared, but we
 829                  * can still add the stripe to batch list
 830                  */
 831                 list_add(&sh->batch_list, &head->batch_list);
 832                 spin_unlock(&head->batch_head->batch_lock);
 833         } else {
 834                 head->batch_head = head;
 835                 sh->batch_head = head->batch_head;
 836                 spin_lock(&head->batch_lock);
 837                 list_add_tail(&sh->batch_list, &head->batch_list);
 838                 spin_unlock(&head->batch_lock);
 839         }
 840
 841         if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 842                 if (atomic_dec_return(&conf->preread_active_stripes)
 843                     < IO_THRESHOLD)
 844                         md_wakeup_thread(conf->mddev->thread);
 845
 846         if (test_and_clear_bit(STRIPE_BIT_DELAY, &sh->state)) {
 847                 int seq = sh->bm_seq;
 848                 if (test_bit(STRIPE_BIT_DELAY, &sh->batch_head->state) &&
 849                     sh->batch_head->bm_seq > seq)
 850                         seq = sh->batch_head->bm_seq;
 851                 set_bit(STRIPE_BIT_DELAY, &sh->batch_head->state);
 852                 sh->batch_head->bm_seq = seq;
 853         }
 854
 855         atomic_inc(&sh->count);
 856 unlock_out:
 857         unlock_two_stripes(head, sh);
 858 out:
 859         raid5_release_stripe(head);
 860 }
 861
 862 /* Determine if 'data_offset' or 'new_data_offset' should be used
 863  * in this stripe_head.
 864  */
 865 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 866 {
 867         sector_t progress = conf->reshape_progress;
 868         /* Need a memory barrier to make sure we see the value
 869          * of conf->generation, or ->data_offset that was set before
 870          * reshape_progress was updated.
 871          */
 872         smp_rmb();
 873         if (progress == MaxSector)
 874                 return 0;
 875         if (sh->generation == conf->generation - 1)
 876                 return 0;
 877         /* We are in a reshape, and this is a new-generation stripe,
 878          * so use new_data_offset.
 879          */
 880         return 1;
 881 }
 882
 883 static void
 884 raid5_end_read_request(struct bio *bi);
 885 static void
 886 raid5_end_write_request(struct bio *bi);
 887
 888 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 889 {
 890         struct r5conf *conf = sh->raid_conf;
 891         int i, disks = sh->disks;
 892         struct stripe_head *head_sh = sh;
 893
 894         might_sleep();
 895
 896         if (r5l_write_stripe(conf->log, sh) == 0)
 897                 return;
 898         for (i = disks; i--; ) {
 899                 int rw;
 900                 int replace_only = 0;
 901                 struct bio *bi, *rbi;
 902                 struct md_rdev *rdev, *rrdev = NULL;
 903
 904                 sh = head_sh;
 905                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 906                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 907                                 rw = WRITE_FUA;
 908                         else
 909                                 rw = WRITE;
 910                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 911                                 rw |= REQ_DISCARD;
 912                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 913                         rw = READ;
 914                 else if (test_and_clear_bit(R5_WantReplace,
 915                                             &sh->dev[i].flags)) {
 916                         rw = WRITE;
 917                         replace_only = 1;
 918                 } else
 919                         continue;
 920                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 921                         rw |= REQ_SYNC;
 922
 923 again:
 924                 bi = &sh->dev[i].req;
 925                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 926
 927                 rcu_read_lock();
 928                 rrdev = rcu_dereference(conf->disks[i].replacement);
 929                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 930                 rdev = rcu_dereference(conf->disks[i].rdev);
 931                 if (!rdev) {
 932                         rdev = rrdev;
 933                         rrdev = NULL;
 934                 }
 935                 if (rw & WRITE) {
 936                         if (replace_only)
 937                                 rdev = NULL;
 938                         if (rdev == rrdev)
 939                                 /* We raced and saw duplicates */
 940                                 rrdev = NULL;
 941                 } else {
 942                         if (test_bit(R5_ReadRepl, &head_sh->dev[i].flags) && rrdev)
 943                                 rdev = rrdev;
 944                         rrdev = NULL;
 945                 }
 946
 947                 if (rdev && test_bit(Faulty, &rdev->flags))
 948                         rdev = NULL;
 949                 if (rdev)
 950                         atomic_inc(&rdev->nr_pending);
 951                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 952                         rrdev = NULL;
 953                 if (rrdev)
 954                         atomic_inc(&rrdev->nr_pending);
 955                 rcu_read_unlock();
 956
 957                 /* We have already checked bad blocks for reads.  Now
 958                  * need to check for writes.  We never accept write errors
 959                  * on the replacement, so we don't to check rrdev.
 960                  */
 961                 while ((rw & WRITE) && rdev &&
 962                        test_bit(WriteErrorSeen, &rdev->flags)) {
 963                         sector_t first_bad;
 964                         int bad_sectors;
 965                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 966                                               &first_bad, &bad_sectors);
 967                         if (!bad)
 968                                 break;
 969
 970                         if (bad < 0) {
 971                                 set_bit(BlockedBadBlocks, &rdev->flags);
 972                                 if (!conf->mddev->external &&
 973                                     conf->mddev->flags) {
 974                                         /* It is very unlikely, but we might
 975                                          * still need to write out the
 976                                          * bad block log - better give it
 977                                          * a chance*/
 978                                         md_check_recovery(conf->mddev);
 979                                 }
 980                                 /*
 981                                  * Because md_wait_for_blocked_rdev
 982                                  * will dec nr_pending, we must
 983                                  * increment it first.
 984                                  */
 985                                 atomic_inc(&rdev->nr_pending);
 986                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
 987                         } else {
 988                                 /* Acknowledged bad block - skip the write */
 989                                 rdev_dec_pending(rdev, conf->mddev);
 990                                 rdev = NULL;
 991                         }
 992                 }
 993
 994                 if (rdev) {
 995                         if (s->syncing || s->expanding || s->expanded
 996                             || s->replacing)
 997                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 998
 999                         set_bit(STRIPE_IO_STARTED, &sh->state);
1000
1001                         bio_reset(bi);
1002                         bi->bi_bdev = rdev->bdev;
1003                         bi->bi_rw = rw;
1004                         bi->bi_end_io = (rw & WRITE)
1005                                 ? raid5_end_write_request
1006                                 : raid5_end_read_request;
1007                         bi->bi_private = sh;
1008
1009                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
1010                                 __func__, (unsigned long long)sh->sector,
1011                                 bi->bi_rw, i);
1012                         atomic_inc(&sh->count);
1013                         if (sh != head_sh)
1014                                 atomic_inc(&head_sh->count);
1015                         if (use_new_offset(conf, sh))
1016                                 bi->bi_iter.bi_sector = (sh->sector
1017                                                  + rdev->new_data_offset);
1018                         else
1019                                 bi->bi_iter.bi_sector = (sh->sector
1020                                                  + rdev->data_offset);
1021                         if (test_bit(R5_ReadNoMerge, &head_sh->dev[i].flags))
1022                                 bi->bi_rw |= REQ_NOMERGE;
1023
1024                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1025                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1026                         sh->dev[i].vec.bv_page = sh->dev[i].page;
1027                         bi->bi_vcnt = 1;
1028                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1029                         bi->bi_io_vec[0].bv_offset = 0;
1030                         bi->bi_iter.bi_size = STRIPE_SIZE;
1031                         /*
1032                          * If this is discard request, set bi_vcnt 0. We don't
1033                          * want to confuse SCSI because SCSI will replace payload
1034                          */
1035                         if (rw & REQ_DISCARD)
1036                                 bi->bi_vcnt = 0;
1037                         if (rrdev)
1038                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
1039
1040                         if (conf->mddev->gendisk)
1041                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
1042                                                       bi, disk_devt(conf->mddev->gendisk),
1043                                                       sh->dev[i].sector);
1044                         generic_make_request(bi);
1045                 }
1046                 if (rrdev) {
1047                         if (s->syncing || s->expanding || s->expanded
1048                             || s->replacing)
1049                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
1050
1051                         set_bit(STRIPE_IO_STARTED, &sh->state);
1052
1053                         bio_reset(rbi);
1054                         rbi->bi_bdev = rrdev->bdev;
1055                         rbi->bi_rw = rw;
1056                         BUG_ON(!(rw & WRITE));
1057                         rbi->bi_end_io = raid5_end_write_request;
1058                         rbi->bi_private = sh;
1059
1060                         pr_debug("%s: for %llu schedule op %ld on "
1061                                  "replacement disc %d\n",
1062                                 __func__, (unsigned long long)sh->sector,
1063                                 rbi->bi_rw, i);
1064                         atomic_inc(&sh->count);
1065                         if (sh != head_sh)
1066                                 atomic_inc(&head_sh->count);
1067                         if (use_new_offset(conf, sh))
1068                                 rbi->bi_iter.bi_sector = (sh->sector
1069                                                   + rrdev->new_data_offset);
1070                         else
1071                                 rbi->bi_iter.bi_sector = (sh->sector
1072                                                   + rrdev->data_offset);
1073                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
1074                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
1075                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
1076                         rbi->bi_vcnt = 1;
1077                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
1078                         rbi->bi_io_vec[0].bv_offset = 0;
1079                         rbi->bi_iter.bi_size = STRIPE_SIZE;
1080                         /*
1081                          * If this is discard request, set bi_vcnt 0. We don't
1082                          * want to confuse SCSI because SCSI will replace payload
1083                          */
1084                         if (rw & REQ_DISCARD)
1085                                 rbi->bi_vcnt = 0;
1086                         if (conf->mddev->gendisk)
1087                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
1088                                                       rbi, disk_devt(conf->mddev->gendisk),
1089                                                       sh->dev[i].sector);
1090                         generic_make_request(rbi);
1091                 }
1092                 if (!rdev && !rrdev) {
1093                         if (rw & WRITE)
1094                                 set_bit(STRIPE_DEGRADED, &sh->state);
1095                         pr_debug("skip op %ld on disc %d for sector %llu\n",
1096                                 bi->bi_rw, i, (unsigned long long)sh->sector);
1097                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
1098                         set_bit(STRIPE_HANDLE, &sh->state);
1099                 }
1100
1101                 if (!head_sh->batch_head)
1102                         continue;
1103                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1104                                       batch_list);
1105                 if (sh != head_sh)
1106                         goto again;
1107         }
1108 }
1109
1110 static struct dma_async_tx_descriptor *
1111 async_copy_data(int frombio, struct bio *bio, struct page **page,
1112         sector_t sector, struct dma_async_tx_descriptor *tx,
1113         struct stripe_head *sh)
1114 {
1115         struct bio_vec bvl;
1116         struct bvec_iter iter;
1117         struct page *bio_page;
1118         int page_offset;
1119         struct async_submit_ctl submit;
1120         enum async_tx_flags flags = 0;
1121
1122         if (bio->bi_iter.bi_sector >= sector)
1123                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
1124         else
1125                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
1126
1127         if (frombio)
1128                 flags |= ASYNC_TX_FENCE;
1129         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
1130
1131         bio_for_each_segment(bvl, bio, iter) {
1132                 int len = bvl.bv_len;
1133                 int clen;
1134                 int b_offset = 0;
1135
1136                 if (page_offset < 0) {
1137                         b_offset = -page_offset;
1138                         page_offset += b_offset;
1139                         len -= b_offset;
1140                 }
1141
1142                 if (len > 0 && page_offset + len > STRIPE_SIZE)
1143                         clen = STRIPE_SIZE - page_offset;
1144                 else
1145                         clen = len;
1146
1147                 if (clen > 0) {
1148                         b_offset += bvl.bv_offset;
1149                         bio_page = bvl.bv_page;
1150                         if (frombio) {
1151                                 if (sh->raid_conf->skip_copy &&
1152                                     b_offset == 0 && page_offset == 0 &&
1153                                     clen == STRIPE_SIZE)
1154                                         *page = bio_page;
1155                                 else
1156                                         tx = async_memcpy(*page, bio_page, page_offset,
1157                                                   b_offset, clen, &submit);
1158                         } else
1159                                 tx = async_memcpy(bio_page, *page, b_offset,
1160                                                   page_offset, clen, &submit);
1161                 }
1162                 /* chain the operations */
1163                 submit.depend_tx = tx;
1164
1165                 if (clen < len) /* hit end of page */
1166                         break;
1167                 page_offset +=  len;
1168         }
1169
1170         return tx;
1171 }
1172
1173 static void ops_complete_biofill(void *stripe_head_ref)
1174 {
1175         struct stripe_head *sh = stripe_head_ref;
1176         struct bio_list return_bi = BIO_EMPTY_LIST;
1177         int i;
1178
1179         pr_debug("%s: stripe %llu\n", __func__,
1180                 (unsigned long long)sh->sector);
1181
1182         /* clear completed biofills */
1183         for (i = sh->disks; i--; ) {
1184                 struct r5dev *dev = &sh->dev[i];
1185
1186                 /* acknowledge completion of a biofill operation */
1187                 /* and check if we need to reply to a read request,
1188                  * new R5_Wantfill requests are held off until
1189                  * !STRIPE_BIOFILL_RUN
1190                  */
1191                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1192                         struct bio *rbi, *rbi2;
1193
1194                         BUG_ON(!dev->read);
1195                         rbi = dev->read;
1196                         dev->read = NULL;
1197                         while (rbi && rbi->bi_iter.bi_sector <
1198                                 dev->sector + STRIPE_SECTORS) {
1199                                 rbi2 = r5_next_bio(rbi, dev->sector);
1200                                 if (!raid5_dec_bi_active_stripes(rbi))
1201                                         bio_list_add(&return_bi, rbi);
1202                                 rbi = rbi2;
1203                         }
1204                 }
1205         }
1206         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1207
1208         return_io(&return_bi);
1209
1210         set_bit(STRIPE_HANDLE, &sh->state);
1211         raid5_release_stripe(sh);
1212 }
1213
1214 static void ops_run_biofill(struct stripe_head *sh)
1215 {
1216         struct dma_async_tx_descriptor *tx = NULL;
1217         struct async_submit_ctl submit;
1218         int i;
1219
1220         BUG_ON(sh->batch_head);
1221         pr_debug("%s: stripe %llu\n", __func__,
1222                 (unsigned long long)sh->sector);
1223
1224         for (i = sh->disks; i--; ) {
1225                 struct r5dev *dev = &sh->dev[i];
1226                 if (test_bit(R5_Wantfill, &dev->flags)) {
1227                         struct bio *rbi;
1228                         spin_lock_irq(&sh->stripe_lock);
1229                         dev->read = rbi = dev->toread;
1230                         dev->toread = NULL;
1231                         spin_unlock_irq(&sh->stripe_lock);
1232                         while (rbi && rbi->bi_iter.bi_sector <
1233                                 dev->sector + STRIPE_SECTORS) {
1234                                 tx = async_copy_data(0, rbi, &dev->page,
1235                                         dev->sector, tx, sh);
1236                                 rbi = r5_next_bio(rbi, dev->sector);
1237                         }
1238                 }
1239         }
1240
1241         atomic_inc(&sh->count);
1242         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1243         async_trigger_callback(&submit);
1244 }
1245
1246 static void mark_target_uptodate(struct stripe_head *sh, int target)
1247 {
1248         struct r5dev *tgt;
1249
1250         if (target < 0)
1251                 return;
1252
1253         tgt = &sh->dev[target];
1254         set_bit(R5_UPTODATE, &tgt->flags);
1255         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1256         clear_bit(R5_Wantcompute, &tgt->flags);
1257 }
1258
1259 static void ops_complete_compute(void *stripe_head_ref)
1260 {
1261         struct stripe_head *sh = stripe_head_ref;
1262
1263         pr_debug("%s: stripe %llu\n", __func__,
1264                 (unsigned long long)sh->sector);
1265
1266         /* mark the computed target(s) as uptodate */
1267         mark_target_uptodate(sh, sh->ops.target);
1268         mark_target_uptodate(sh, sh->ops.target2);
1269
1270         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1271         if (sh->check_state == check_state_compute_run)
1272                 sh->check_state = check_state_compute_result;
1273         set_bit(STRIPE_HANDLE, &sh->state);
1274         raid5_release_stripe(sh);
1275 }
1276
1277 /* return a pointer to the address conversion region of the scribble buffer */
1278 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1279                                  struct raid5_percpu *percpu, int i)
1280 {
1281         void *addr;
1282
1283         addr = flex_array_get(percpu->scribble, i);
1284         return addr + sizeof(struct page *) * (sh->disks + 2);
1285 }
1286
1287 /* return a pointer to the address conversion region of the scribble buffer */
1288 static struct page **to_addr_page(struct raid5_percpu *percpu, int i)
1289 {
1290         void *addr;
1291
1292         addr = flex_array_get(percpu->scribble, i);
1293         return addr;
1294 }
1295
1296 static struct dma_async_tx_descriptor *
1297 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1298 {
1299         int disks = sh->disks;
1300         struct page **xor_srcs = to_addr_page(percpu, 0);
1301         int target = sh->ops.target;
1302         struct r5dev *tgt = &sh->dev[target];
1303         struct page *xor_dest = tgt->page;
1304         int count = 0;
1305         struct dma_async_tx_descriptor *tx;
1306         struct async_submit_ctl submit;
1307         int i;
1308
1309         BUG_ON(sh->batch_head);
1310
1311         pr_debug("%s: stripe %llu block: %d\n",
1312                 __func__, (unsigned long long)sh->sector, target);
1313         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1314
1315         for (i = disks; i--; )
1316                 if (i != target)
1317                         xor_srcs[count++] = sh->dev[i].page;
1318
1319         atomic_inc(&sh->count);
1320
1321         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1322                           ops_complete_compute, sh, to_addr_conv(sh, percpu, 0));
1323         if (unlikely(count == 1))
1324                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1325         else
1326                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1327
1328         return tx;
1329 }
1330
1331 /* set_syndrome_sources - populate source buffers for gen_syndrome
1332  * @srcs - (struct page *) array of size sh->disks
1333  * @sh - stripe_head to parse
1334  *
1335  * Populates srcs in proper layout order for the stripe and returns the
1336  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1337  * destination buffer is recorded in srcs[count] and the Q destination
1338  * is recorded in srcs[count+1]].
1339  */
1340 static int set_syndrome_sources(struct page **srcs,
1341                                 struct stripe_head *sh,
1342                                 int srctype)
1343 {
1344         int disks = sh->disks;
1345         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1346         int d0_idx = raid6_d0(sh);
1347         int count;
1348         int i;
1349
1350         for (i = 0; i < disks; i++)
1351                 srcs[i] = NULL;
1352
1353         count = 0;
1354         i = d0_idx;
1355         do {
1356                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1357                 struct r5dev *dev = &sh->dev[i];
1358
1359                 if (i == sh->qd_idx || i == sh->pd_idx ||
1360                     (srctype == SYNDROME_SRC_ALL) ||
1361                     (srctype == SYNDROME_SRC_WANT_DRAIN &&
1362                      test_bit(R5_Wantdrain, &dev->flags)) ||
1363                     (srctype == SYNDROME_SRC_WRITTEN &&
1364                      dev->written))
1365                         srcs[slot] = sh->dev[i].page;
1366                 i = raid6_next_disk(i, disks);
1367         } while (i != d0_idx);
1368
1369         return syndrome_disks;
1370 }
1371
1372 static struct dma_async_tx_descriptor *
1373 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1374 {
1375         int disks = sh->disks;
1376         struct page **blocks = to_addr_page(percpu, 0);
1377         int target;
1378         int qd_idx = sh->qd_idx;
1379         struct dma_async_tx_descriptor *tx;
1380         struct async_submit_ctl submit;
1381         struct r5dev *tgt;
1382         struct page *dest;
1383         int i;
1384         int count;
1385
1386         BUG_ON(sh->batch_head);
1387         if (sh->ops.target < 0)
1388                 target = sh->ops.target2;
1389         else if (sh->ops.target2 < 0)
1390                 target = sh->ops.target;
1391         else
1392                 /* we should only have one valid target */
1393                 BUG();
1394         BUG_ON(target < 0);
1395         pr_debug("%s: stripe %llu block: %d\n",
1396                 __func__, (unsigned long long)sh->sector, target);
1397
1398         tgt = &sh->dev[target];
1399         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1400         dest = tgt->page;
1401
1402         atomic_inc(&sh->count);
1403
1404         if (target == qd_idx) {
1405                 count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1406                 blocks[count] = NULL; /* regenerating p is not necessary */
1407                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1408                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1409                                   ops_complete_compute, sh,
1410                                   to_addr_conv(sh, percpu, 0));
1411                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1412         } else {
1413                 /* Compute any data- or p-drive using XOR */
1414                 count = 0;
1415                 for (i = disks; i-- ; ) {
1416                         if (i == target || i == qd_idx)
1417                                 continue;
1418                         blocks[count++] = sh->dev[i].page;
1419                 }
1420
1421                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1422                                   NULL, ops_complete_compute, sh,
1423                                   to_addr_conv(sh, percpu, 0));
1424                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1425         }
1426
1427         return tx;
1428 }
1429
1430 static struct dma_async_tx_descriptor *
1431 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1432 {
1433         int i, count, disks = sh->disks;
1434         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1435         int d0_idx = raid6_d0(sh);
1436         int faila = -1, failb = -1;
1437         int target = sh->ops.target;
1438         int target2 = sh->ops.target2;
1439         struct r5dev *tgt = &sh->dev[target];
1440         struct r5dev *tgt2 = &sh->dev[target2];
1441         struct dma_async_tx_descriptor *tx;
1442         struct page **blocks = to_addr_page(percpu, 0);
1443         struct async_submit_ctl submit;
1444
1445         BUG_ON(sh->batch_head);
1446         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1447                  __func__, (unsigned long long)sh->sector, target, target2);
1448         BUG_ON(target < 0 || target2 < 0);
1449         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1450         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1451
1452         /* we need to open-code set_syndrome_sources to handle the
1453          * slot number conversion for 'faila' and 'failb'
1454          */
1455         for (i = 0; i < disks ; i++)
1456                 blocks[i] = NULL;
1457         count = 0;
1458         i = d0_idx;
1459         do {
1460                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1461
1462                 blocks[slot] = sh->dev[i].page;
1463
1464                 if (i == target)
1465                         faila = slot;
1466                 if (i == target2)
1467                         failb = slot;
1468                 i = raid6_next_disk(i, disks);
1469         } while (i != d0_idx);
1470
1471         BUG_ON(faila == failb);
1472         if (failb < faila)
1473                 swap(faila, failb);
1474         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1475                  __func__, (unsigned long long)sh->sector, faila, failb);
1476
1477         atomic_inc(&sh->count);
1478
1479         if (failb == syndrome_disks+1) {
1480                 /* Q disk is one of the missing disks */
1481                 if (faila == syndrome_disks) {
1482                         /* Missing P+Q, just recompute */
1483                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1484                                           ops_complete_compute, sh,
1485                                           to_addr_conv(sh, percpu, 0));
1486                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1487                                                   STRIPE_SIZE, &submit);
1488                 } else {
1489                         struct page *dest;
1490                         int data_target;
1491                         int qd_idx = sh->qd_idx;
1492
1493                         /* Missing D+Q: recompute D from P, then recompute Q */
1494                         if (target == qd_idx)
1495                                 data_target = target2;
1496                         else
1497                                 data_target = target;
1498
1499                         count = 0;
1500                         for (i = disks; i-- ; ) {
1501                                 if (i == data_target || i == qd_idx)
1502                                         continue;
1503                                 blocks[count++] = sh->dev[i].page;
1504                         }
1505                         dest = sh->dev[data_target].page;
1506                         init_async_submit(&submit,
1507                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1508                                           NULL, NULL, NULL,
1509                                           to_addr_conv(sh, percpu, 0));
1510                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1511                                        &submit);
1512
1513                         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_ALL);
1514                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1515                                           ops_complete_compute, sh,
1516                                           to_addr_conv(sh, percpu, 0));
1517                         return async_gen_syndrome(blocks, 0, count+2,
1518                                                   STRIPE_SIZE, &submit);
1519                 }
1520         } else {
1521                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1522                                   ops_complete_compute, sh,
1523                                   to_addr_conv(sh, percpu, 0));
1524                 if (failb == syndrome_disks) {
1525                         /* We're missing D+P. */
1526                         return async_raid6_datap_recov(syndrome_disks+2,
1527                                                        STRIPE_SIZE, faila,
1528                                                        blocks, &submit);
1529                 } else {
1530                         /* We're missing D+D. */
1531                         return async_raid6_2data_recov(syndrome_disks+2,
1532                                                        STRIPE_SIZE, faila, failb,
1533                                                        blocks, &submit);
1534                 }
1535         }
1536 }
1537
1538 static void ops_complete_prexor(void *stripe_head_ref)
1539 {
1540         struct stripe_head *sh = stripe_head_ref;
1541
1542         pr_debug("%s: stripe %llu\n", __func__,
1543                 (unsigned long long)sh->sector);
1544 }
1545
1546 static struct dma_async_tx_descriptor *
1547 ops_run_prexor5(struct stripe_head *sh, struct raid5_percpu *percpu,
1548                 struct dma_async_tx_descriptor *tx)
1549 {
1550         int disks = sh->disks;
1551         struct page **xor_srcs = to_addr_page(percpu, 0);
1552         int count = 0, pd_idx = sh->pd_idx, i;
1553         struct async_submit_ctl submit;
1554
1555         /* existing parity data subtracted */
1556         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1557
1558         BUG_ON(sh->batch_head);
1559         pr_debug("%s: stripe %llu\n", __func__,
1560                 (unsigned long long)sh->sector);
1561
1562         for (i = disks; i--; ) {
1563                 struct r5dev *dev = &sh->dev[i];
1564                 /* Only process blocks that are known to be uptodate */
1565                 if (test_bit(R5_Wantdrain, &dev->flags))
1566                         xor_srcs[count++] = dev->page;
1567         }
1568
1569         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1570                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1571         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1572
1573         return tx;
1574 }
1575
1576 static struct dma_async_tx_descriptor *
1577 ops_run_prexor6(struct stripe_head *sh, struct raid5_percpu *percpu,
1578                 struct dma_async_tx_descriptor *tx)
1579 {
1580         struct page **blocks = to_addr_page(percpu, 0);
1581         int count;
1582         struct async_submit_ctl submit;
1583
1584         pr_debug("%s: stripe %llu\n", __func__,
1585                 (unsigned long long)sh->sector);
1586
1587         count = set_syndrome_sources(blocks, sh, SYNDROME_SRC_WANT_DRAIN);
1588
1589         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_PQ_XOR_DST, tx,
1590                           ops_complete_prexor, sh, to_addr_conv(sh, percpu, 0));
1591         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1592
1593         return tx;
1594 }
1595
1596 static struct dma_async_tx_descriptor *
1597 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1598 {
1599         int disks = sh->disks;
1600         int i;
1601         struct stripe_head *head_sh = sh;
1602
1603         pr_debug("%s: stripe %llu\n", __func__,
1604                 (unsigned long long)sh->sector);
1605
1606         for (i = disks; i--; ) {
1607                 struct r5dev *dev;
1608                 struct bio *chosen;
1609
1610                 sh = head_sh;
1611                 if (test_and_clear_bit(R5_Wantdrain, &head_sh->dev[i].flags)) {
1612                         struct bio *wbi;
1613
1614 again:
1615                         dev = &sh->dev[i];
1616                         spin_lock_irq(&sh->stripe_lock);
1617                         chosen = dev->towrite;
1618                         dev->towrite = NULL;
1619                         sh->overwrite_disks = 0;
1620                         BUG_ON(dev->written);
1621                         wbi = dev->written = chosen;
1622                         spin_unlock_irq(&sh->stripe_lock);
1623                         WARN_ON(dev->page != dev->orig_page);
1624
1625                         while (wbi && wbi->bi_iter.bi_sector <
1626                                 dev->sector + STRIPE_SECTORS) {
1627                                 if (wbi->bi_rw & REQ_FUA)
1628                                         set_bit(R5_WantFUA, &dev->flags);
1629                                 if (wbi->bi_rw & REQ_SYNC)
1630                                         set_bit(R5_SyncIO, &dev->flags);
1631                                 if (wbi->bi_rw & REQ_DISCARD)
1632                                         set_bit(R5_Discard, &dev->flags);
1633                                 else {
1634                                         tx = async_copy_data(1, wbi, &dev->page,
1635                                                 dev->sector, tx, sh);
1636                                         if (dev->page != dev->orig_page) {
1637                                                 set_bit(R5_SkipCopy, &dev->flags);
1638                                                 clear_bit(R5_UPTODATE, &dev->flags);
1639                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1640                                         }
1641                                 }
1642                                 wbi = r5_next_bio(wbi, dev->sector);
1643                         }
1644
1645                         if (head_sh->batch_head) {
1646                                 sh = list_first_entry(&sh->batch_list,
1647                                                       struct stripe_head,
1648                                                       batch_list);
1649                                 if (sh == head_sh)
1650                                         continue;
1651                                 goto again;
1652                         }
1653                 }
1654         }
1655
1656         return tx;
1657 }
1658
1659 static void ops_complete_reconstruct(void *stripe_head_ref)
1660 {
1661         struct stripe_head *sh = stripe_head_ref;
1662         int disks = sh->disks;
1663         int pd_idx = sh->pd_idx;
1664         int qd_idx = sh->qd_idx;
1665         int i;
1666         bool fua = false, sync = false, discard = false;
1667
1668         pr_debug("%s: stripe %llu\n", __func__,
1669                 (unsigned long long)sh->sector);
1670
1671         for (i = disks; i--; ) {
1672                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1673                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1674                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1675         }
1676
1677         for (i = disks; i--; ) {
1678                 struct r5dev *dev = &sh->dev[i];
1679
1680                 if (dev->written || i == pd_idx || i == qd_idx) {
1681                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags)) {
1682                                 set_bit(R5_UPTODATE, &dev->flags);
1683                                 if (test_bit(STRIPE_EXPAND_READY, &sh->state))
1684                                         set_bit(R5_Expanded, &dev->flags);
1685                         }
1686                         if (fua)
1687                                 set_bit(R5_WantFUA, &dev->flags);
1688                         if (sync)
1689                                 set_bit(R5_SyncIO, &dev->flags);
1690                 }
1691         }
1692
1693         if (sh->reconstruct_state == reconstruct_state_drain_run)
1694                 sh->reconstruct_state = reconstruct_state_drain_result;
1695         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1696                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1697         else {
1698                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1699                 sh->reconstruct_state = reconstruct_state_result;
1700         }
1701
1702         set_bit(STRIPE_HANDLE, &sh->state);
1703         raid5_release_stripe(sh);
1704 }
1705
1706 static void
1707 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1708                      struct dma_async_tx_descriptor *tx)
1709 {
1710         int disks = sh->disks;
1711         struct page **xor_srcs;
1712         struct async_submit_ctl submit;
1713         int count, pd_idx = sh->pd_idx, i;
1714         struct page *xor_dest;
1715         int prexor = 0;
1716         unsigned long flags;
1717         int j = 0;
1718         struct stripe_head *head_sh = sh;
1719         int last_stripe;
1720
1721         pr_debug("%s: stripe %llu\n", __func__,
1722                 (unsigned long long)sh->sector);
1723
1724         for (i = 0; i < sh->disks; i++) {
1725                 if (pd_idx == i)
1726                         continue;
1727                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1728                         break;
1729         }
1730         if (i >= sh->disks) {
1731                 atomic_inc(&sh->count);
1732                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1733                 ops_complete_reconstruct(sh);
1734                 return;
1735         }
1736 again:
1737         count = 0;
1738         xor_srcs = to_addr_page(percpu, j);
1739         /* check if prexor is active which means only process blocks
1740          * that are part of a read-modify-write (written)
1741          */
1742         if (head_sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1743                 prexor = 1;
1744                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1745                 for (i = disks; i--; ) {
1746                         struct r5dev *dev = &sh->dev[i];
1747                         if (head_sh->dev[i].written)
1748                                 xor_srcs[count++] = dev->page;
1749                 }
1750         } else {
1751                 xor_dest = sh->dev[pd_idx].page;
1752                 for (i = disks; i--; ) {
1753                         struct r5dev *dev = &sh->dev[i];
1754                         if (i != pd_idx)
1755                                 xor_srcs[count++] = dev->page;
1756                 }
1757         }
1758
1759         /* 1/ if we prexor'd then the dest is reused as a source
1760          * 2/ if we did not prexor then we are redoing the parity
1761          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1762          * for the synchronous xor case
1763          */
1764         last_stripe = !head_sh->batch_head ||
1765                 list_first_entry(&sh->batch_list,
1766                                  struct stripe_head, batch_list) == head_sh;
1767         if (last_stripe) {
1768                 flags = ASYNC_TX_ACK |
1769                         (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1770
1771                 atomic_inc(&head_sh->count);
1772                 init_async_submit(&submit, flags, tx, ops_complete_reconstruct, head_sh,
1773                                   to_addr_conv(sh, percpu, j));
1774         } else {
1775                 flags = prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST;
1776                 init_async_submit(&submit, flags, tx, NULL, NULL,
1777                                   to_addr_conv(sh, percpu, j));
1778         }
1779
1780         if (unlikely(count == 1))
1781                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1782         else
1783                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1784         if (!last_stripe) {
1785                 j++;
1786                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1787                                       batch_list);
1788                 goto again;
1789         }
1790 }
1791
1792 static void
1793 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1794                      struct dma_async_tx_descriptor *tx)
1795 {
1796         struct async_submit_ctl submit;
1797         struct page **blocks;
1798         int count, i, j = 0;
1799         struct stripe_head *head_sh = sh;
1800         int last_stripe;
1801         int synflags;
1802         unsigned long txflags;
1803
1804         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1805
1806         for (i = 0; i < sh->disks; i++) {
1807                 if (sh->pd_idx == i || sh->qd_idx == i)
1808                         continue;
1809                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1810                         break;
1811         }
1812         if (i >= sh->disks) {
1813                 atomic_inc(&sh->count);
1814                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1815                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1816                 ops_complete_reconstruct(sh);
1817                 return;
1818         }
1819
1820 again:
1821         blocks = to_addr_page(percpu, j);
1822
1823         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1824                 synflags = SYNDROME_SRC_WRITTEN;
1825                 txflags = ASYNC_TX_ACK | ASYNC_TX_PQ_XOR_DST;
1826         } else {
1827                 synflags = SYNDROME_SRC_ALL;
1828                 txflags = ASYNC_TX_ACK;
1829         }
1830
1831         count = set_syndrome_sources(blocks, sh, synflags);
1832         last_stripe = !head_sh->batch_head ||
1833                 list_first_entry(&sh->batch_list,
1834                                  struct stripe_head, batch_list) == head_sh;
1835
1836         if (last_stripe) {
1837                 atomic_inc(&head_sh->count);
1838                 init_async_submit(&submit, txflags, tx, ops_complete_reconstruct,
1839                                   head_sh, to_addr_conv(sh, percpu, j));
1840         } else
1841                 init_async_submit(&submit, 0, tx, NULL, NULL,
1842                                   to_addr_conv(sh, percpu, j));
1843         tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1844         if (!last_stripe) {
1845                 j++;
1846                 sh = list_first_entry(&sh->batch_list, struct stripe_head,
1847                                       batch_list);
1848                 goto again;
1849         }
1850 }
1851
1852 static void ops_complete_check(void *stripe_head_ref)
1853 {
1854         struct stripe_head *sh = stripe_head_ref;
1855
1856         pr_debug("%s: stripe %llu\n", __func__,
1857                 (unsigned long long)sh->sector);
1858
1859         sh->check_state = check_state_check_result;
1860         set_bit(STRIPE_HANDLE, &sh->state);
1861         raid5_release_stripe(sh);
1862 }
1863
1864 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1865 {
1866         int disks = sh->disks;
1867         int pd_idx = sh->pd_idx;
1868         int qd_idx = sh->qd_idx;
1869         struct page *xor_dest;
1870         struct page **xor_srcs = to_addr_page(percpu, 0);
1871         struct dma_async_tx_descriptor *tx;
1872         struct async_submit_ctl submit;
1873         int count;
1874         int i;
1875
1876         pr_debug("%s: stripe %llu\n", __func__,
1877                 (unsigned long long)sh->sector);
1878
1879         BUG_ON(sh->batch_head);
1880         count = 0;
1881         xor_dest = sh->dev[pd_idx].page;
1882         xor_srcs[count++] = xor_dest;
1883         for (i = disks; i--; ) {
1884                 if (i == pd_idx || i == qd_idx)
1885                         continue;
1886                 xor_srcs[count++] = sh->dev[i].page;
1887         }
1888
1889         init_async_submit(&submit, 0, NULL, NULL, NULL,
1890                           to_addr_conv(sh, percpu, 0));
1891         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1892                            &sh->ops.zero_sum_result, &submit);
1893
1894         atomic_inc(&sh->count);
1895         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1896         tx = async_trigger_callback(&submit);
1897 }
1898
1899 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1900 {
1901         struct page **srcs = to_addr_page(percpu, 0);
1902         struct async_submit_ctl submit;
1903         int count;
1904
1905         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1906                 (unsigned long long)sh->sector, checkp);
1907
1908         BUG_ON(sh->batch_head);
1909         count = set_syndrome_sources(srcs, sh, SYNDROME_SRC_ALL);
1910         if (!checkp)
1911                 srcs[count] = NULL;
1912
1913         atomic_inc(&sh->count);
1914         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1915                           sh, to_addr_conv(sh, percpu, 0));
1916         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1917                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1918 }
1919
1920 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1921 {
1922         int overlap_clear = 0, i, disks = sh->disks;
1923         struct dma_async_tx_descriptor *tx = NULL;
1924         struct r5conf *conf = sh->raid_conf;
1925         int level = conf->level;
1926         struct raid5_percpu *percpu;
1927         unsigned long cpu;
1928
1929         cpu = get_cpu();
1930         percpu = per_cpu_ptr(conf->percpu, cpu);
1931         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1932                 ops_run_biofill(sh);
1933                 overlap_clear++;
1934         }
1935
1936         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1937                 if (level < 6)
1938                         tx = ops_run_compute5(sh, percpu);
1939                 else {
1940                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1941                                 tx = ops_run_compute6_1(sh, percpu);
1942                         else
1943                                 tx = ops_run_compute6_2(sh, percpu);
1944                 }
1945                 /* terminate the chain if reconstruct is not set to be run */
1946                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1947                         async_tx_ack(tx);
1948         }
1949
1950         if (test_bit(STRIPE_OP_PREXOR, &ops_request)) {
1951                 if (level < 6)
1952                         tx = ops_run_prexor5(sh, percpu, tx);
1953                 else
1954                         tx = ops_run_prexor6(sh, percpu, tx);
1955         }
1956
1957         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1958                 tx = ops_run_biodrain(sh, tx);
1959                 overlap_clear++;
1960         }
1961
1962         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1963                 if (level < 6)
1964                         ops_run_reconstruct5(sh, percpu, tx);
1965                 else
1966                         ops_run_reconstruct6(sh, percpu, tx);
1967         }
1968
1969         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1970                 if (sh->check_state == check_state_run)
1971                         ops_run_check_p(sh, percpu);
1972                 else if (sh->check_state == check_state_run_q)
1973                         ops_run_check_pq(sh, percpu, 0);
1974                 else if (sh->check_state == check_state_run_pq)
1975                         ops_run_check_pq(sh, percpu, 1);
1976                 else
1977                         BUG();
1978         }
1979
1980         if (overlap_clear && !sh->batch_head)
1981                 for (i = disks; i--; ) {
1982                         struct r5dev *dev = &sh->dev[i];
1983                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1984                                 wake_up(&sh->raid_conf->wait_for_overlap);
1985                 }
1986         put_cpu();
1987 }
1988
1989 static struct stripe_head *alloc_stripe(struct kmem_cache *sc, gfp_t gfp)
1990 {
1991         struct stripe_head *sh;
1992
1993         sh = kmem_cache_zalloc(sc, gfp);
1994         if (sh) {
1995                 spin_lock_init(&sh->stripe_lock);
1996                 spin_lock_init(&sh->batch_lock);
1997                 INIT_LIST_HEAD(&sh->batch_list);
1998                 INIT_LIST_HEAD(&sh->lru);
1999                 atomic_set(&sh->count, 1);
2000         }
2001         return sh;
2002 }
2003 static int grow_one_stripe(struct r5conf *conf, gfp_t gfp)
2004 {
2005         struct stripe_head *sh;
2006
2007         sh = alloc_stripe(conf->slab_cache, gfp);
2008         if (!sh)
2009                 return 0;
2010
2011         sh->raid_conf = conf;
2012
2013         if (grow_buffers(sh, gfp)) {
2014                 shrink_buffers(sh);
2015                 kmem_cache_free(conf->slab_cache, sh);
2016                 return 0;
2017         }
2018         sh->hash_lock_index =
2019                 conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
2020         /* we just created an active stripe so... */
2021         atomic_inc(&conf->active_stripes);
2022
2023         raid5_release_stripe(sh);
2024         conf->max_nr_stripes++;
2025         return 1;
2026 }
2027
2028 static int grow_stripes(struct r5conf *conf, int num)
2029 {
2030         struct kmem_cache *sc;
2031         size_t namelen = sizeof(conf->cache_name[0]);
2032         int devs = max(conf->raid_disks, conf->previous_raid_disks);
2033
2034         if (conf->mddev->gendisk)
2035                 snprintf(conf->cache_name[0], namelen,
2036                         "raid%d-%s", conf->level, mdname(conf->mddev));
2037         else
2038                 snprintf(conf->cache_name[0], namelen,
2039                         "raid%d-%p", conf->level, conf->mddev);
2040         snprintf(conf->cache_name[1], namelen, "%.27s-alt", conf->cache_name[0]);
2041
2042         conf->active_name = 0;
2043         sc = kmem_cache_create(conf->cache_name[conf->active_name],
2044                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
2045                                0, 0, NULL);
2046         if (!sc)
2047                 return 1;
2048         conf->slab_cache = sc;
2049         conf->pool_size = devs;
2050         while (num--)
2051                 if (!grow_one_stripe(conf, GFP_KERNEL))
2052                         return 1;
2053
2054         return 0;
2055 }
2056
2057 /**
2058  * scribble_len - return the required size of the scribble region
2059  * @num - total number of disks in the array
2060  *
2061  * The size must be enough to contain:
2062  * 1/ a struct page pointer for each device in the array +2
2063  * 2/ room to convert each entry in (1) to its corresponding dma
2064  *    (dma_map_page()) or page (page_address()) address.
2065  *
2066  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
2067  * calculate over all devices (not just the data blocks), using zeros in place
2068  * of the P and Q blocks.
2069  */
2070 static struct flex_array *scribble_alloc(int num, int cnt, gfp_t flags)
2071 {
2072         struct flex_array *ret;
2073         size_t len;
2074
2075         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
2076         ret = flex_array_alloc(len, cnt, flags);
2077         if (!ret)
2078                 return NULL;
2079         /* always prealloc all elements, so no locking is required */
2080         if (flex_array_prealloc(ret, 0, cnt, flags)) {
2081                 flex_array_free(ret);
2082                 return NULL;
2083         }
2084         return ret;
2085 }
2086
2087 static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
2088 {
2089         unsigned long cpu;
2090         int err = 0;
2091
2092         /*
2093          * Never shrink. And mddev_suspend() could deadlock if this is called
2094          * from raid5d. In that case, scribble_disks and scribble_sectors
2095          * should equal to new_disks and new_sectors
2096          */
2097         if (conf->scribble_disks >= new_disks &&
2098             conf->scribble_sectors >= new_sectors)
2099                 return 0;
2100         mddev_suspend(conf->mddev);
2101         get_online_cpus();
2102         for_each_present_cpu(cpu) {
2103                 struct raid5_percpu *percpu;
2104                 struct flex_array *scribble;
2105
2106                 percpu = per_cpu_ptr(conf->percpu, cpu);
2107                 scribble = scribble_alloc(new_disks,
2108                                           new_sectors / STRIPE_SECTORS,
2109                                           GFP_NOIO);
2110
2111                 if (scribble) {
2112                         flex_array_free(percpu->scribble);
2113                         percpu->scribble = scribble;
2114                 } else {
2115                         err = -ENOMEM;
2116                         break;
2117                 }
2118         }
2119         put_online_cpus();
2120         mddev_resume(conf->mddev);
2121         if (!err) {
2122                 conf->scribble_disks = new_disks;
2123                 conf->scribble_sectors = new_sectors;
2124         }
2125         return err;
2126 }
2127
2128 static int resize_stripes(struct r5conf *conf, int newsize)
2129 {
2130         /* Make all the stripes able to hold 'newsize' devices.
2131          * New slots in each stripe get 'page' set to a new page.
2132          *
2133          * This happens in stages:
2134          * 1/ create a new kmem_cache and allocate the required number of
2135          *    stripe_heads.
2136          * 2/ gather all the old stripe_heads and transfer the pages across
2137          *    to the new stripe_heads.  This will have the side effect of
2138          *    freezing the array as once all stripe_heads have been collected,
2139          *    no IO will be possible.  Old stripe heads are freed once their
2140          *    pages have been transferred over, and the old kmem_cache is
2141          *    freed when all stripes are done.
2142          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
2143          *    we simple return a failre status - no need to clean anything up.
2144          * 4/ allocate new pages for the new slots in the new stripe_heads.
2145          *    If this fails, we don't bother trying the shrink the
2146          *    stripe_heads down again, we just leave them as they are.
2147          *    As each stripe_head is processed the new one is released into
2148          *    active service.
2149          *
2150          * Once step2 is started, we cannot afford to wait for a write,
2151          * so we use GFP_NOIO allocations.
2152          */
2153         struct stripe_head *osh, *nsh;
2154         LIST_HEAD(newstripes);
2155         struct disk_info *ndisks;
2156         int err;
2157         struct kmem_cache *sc;
2158         int i;
2159         int hash, cnt;
2160
2161         if (newsize <= conf->pool_size)
2162                 return 0; /* never bother to shrink */
2163
2164         err = md_allow_write(conf->mddev);
2165         if (err)
2166                 return err;
2167
2168         /* Step 1 */
2169         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
2170                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
2171                                0, 0, NULL);
2172         if (!sc)
2173                 return -ENOMEM;
2174
2175         /* Need to ensure auto-resizing doesn't interfere */
2176         mutex_lock(&conf->cache_size_mutex);
2177
2178         for (i = conf->max_nr_stripes; i; i--) {
2179                 nsh = alloc_stripe(sc, GFP_KERNEL);
2180                 if (!nsh)
2181                         break;
2182
2183                 nsh->raid_conf = conf;
2184                 list_add(&nsh->lru, &newstripes);
2185         }
2186         if (i) {
2187                 /* didn't get enough, give up */
2188                 while (!list_empty(&newstripes)) {
2189                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
2190                         list_del(&nsh->lru);
2191                         kmem_cache_free(sc, nsh);
2192                 }
2193                 kmem_cache_destroy(sc);
2194                 mutex_unlock(&conf->cache_size_mutex);
2195                 return -ENOMEM;
2196         }
2197         /* Step 2 - Must use GFP_NOIO now.
2198          * OK, we have enough stripes, start collecting inactive
2199          * stripes and copying them over
2200          */
2201         hash = 0;
2202         cnt = 0;
2203         list_for_each_entry(nsh, &newstripes, lru) {
2204                 lock_device_hash_lock(conf, hash);
2205                 wait_event_cmd(conf->wait_for_stripe,
2206                                     !list_empty(conf->inactive_list + hash),
2207                                     unlock_device_hash_lock(conf, hash),
2208                                     lock_device_hash_lock(conf, hash));
2209                 osh = get_free_stripe(conf, hash);
2210                 unlock_device_hash_lock(conf, hash);
2211
2212                 for(i=0; i<conf->pool_size; i++) {
2213                         nsh->dev[i].page = osh->dev[i].page;
2214                         nsh->dev[i].orig_page = osh->dev[i].page;
2215                 }
2216                 nsh->hash_lock_index = hash;
2217                 kmem_cache_free(conf->slab_cache, osh);
2218                 cnt++;
2219                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
2220                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
2221                         hash++;
2222                         cnt = 0;
2223                 }
2224         }
2225         kmem_cache_destroy(conf->slab_cache);
2226
2227         /* Step 3.
2228          * At this point, we are holding all the stripes so the array
2229          * is completely stalled, so now is a good time to resize
2230          * conf->disks and the scribble region
2231          */
2232         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
2233         if (ndisks) {
2234                 for (i=0; i<conf->raid_disks; i++)
2235                         ndisks[i] = conf->disks[i];
2236                 kfree(conf->disks);
2237                 conf->disks = ndisks;
2238         } else
2239                 err = -ENOMEM;
2240
2241         conf->slab_cache = sc;
2242         conf->active_name = 1-conf->active_name;
2243
2244         /* Step 4, return new stripes to service */
2245         while(!list_empty(&newstripes)) {
2246                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
2247                 list_del_init(&nsh->lru);
2248
2249                 for (i=conf->raid_disks; i < newsize; i++)
2250                         if (nsh->dev[i].page == NULL) {
2251                                 struct page *p = alloc_page(GFP_NOIO);
2252                                 nsh->dev[i].page = p;
2253                                 nsh->dev[i].orig_page = p;
2254                                 if (!p)
2255                                         err = -ENOMEM;
2256                         }
2257                 raid5_release_stripe(nsh);
2258         }
2259         /* critical section pass, GFP_NOIO no longer needed */
2260
2261         if (!err)
2262                 conf->pool_size = newsize;
2263         mutex_unlock(&conf->cache_size_mutex);
2264
2265         return err;
2266 }
2267
2268 static int drop_one_stripe(struct r5conf *conf)
2269 {
2270         struct stripe_head *sh;
2271         int hash = (conf->max_nr_stripes - 1) & STRIPE_HASH_LOCKS_MASK;
2272
2273         spin_lock_irq(conf->hash_locks + hash);
2274         sh = get_free_stripe(conf, hash);
2275         spin_unlock_irq(conf->hash_locks + hash);
2276         if (!sh)
2277                 return 0;
2278         BUG_ON(atomic_read(&sh->count));
2279         shrink_buffers(sh);
2280         kmem_cache_free(conf->slab_cache, sh);
2281         atomic_dec(&conf->active_stripes);
2282         conf->max_nr_stripes--;
2283         return 1;
2284 }
2285
2286 static void shrink_stripes(struct r5conf *conf)
2287 {
2288         while (conf->max_nr_stripes &&
2289                drop_one_stripe(conf))
2290                 ;
2291
2292         kmem_cache_destroy(conf->slab_cache);
2293         conf->slab_cache = NULL;
2294 }
2295
2296 static void raid5_end_read_request(struct bio * bi)
2297 {
2298         struct stripe_head *sh = bi->bi_private;
2299         struct r5conf *conf = sh->raid_conf;
2300         int disks = sh->disks, i;
2301         char b[BDEVNAME_SIZE];
2302         struct md_rdev *rdev = NULL;
2303         sector_t s;
2304
2305         for (i=0 ; i<disks; i++)
2306                 if (bi == &sh->dev[i].req)
2307                         break;
2308
2309         pr_debug("end_read_request %llu/%d, count: %d, error %d.\n",
2310                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2311                 bi->bi_error);
2312         if (i == disks) {
2313                 BUG();
2314                 return;
2315         }
2316         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2317                 /* If replacement finished while this request was outstanding,
2318                  * 'replacement' might be NULL already.
2319                  * In that case it moved down to 'rdev'.
2320                  * rdev is not removed until all requests are finished.
2321                  */
2322                 rdev = conf->disks[i].replacement;
2323         if (!rdev)
2324                 rdev = conf->disks[i].rdev;
2325
2326         if (use_new_offset(conf, sh))
2327                 s = sh->sector + rdev->new_data_offset;
2328         else
2329                 s = sh->sector + rdev->data_offset;
2330         if (!bi->bi_error) {
2331                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2332                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2333                         /* Note that this cannot happen on a
2334                          * replacement device.  We just fail those on
2335                          * any error
2336                          */
2337                         printk_ratelimited(
2338                                 KERN_INFO
2339                                 "md/raid:%s: read error corrected"
2340                                 " (%lu sectors at %llu on %s)\n",
2341                                 mdname(conf->mddev), STRIPE_SECTORS,
2342                                 (unsigned long long)s,
2343                                 bdevname(rdev->bdev, b));
2344                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2345                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2346                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2347                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2348                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2349
2350                 if (atomic_read(&rdev->read_errors))
2351                         atomic_set(&rdev->read_errors, 0);
2352         } else {
2353                 const char *bdn = bdevname(rdev->bdev, b);
2354                 int retry = 0;
2355                 int set_bad = 0;
2356
2357                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2358                 atomic_inc(&rdev->read_errors);
2359                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2360                         printk_ratelimited(
2361                                 KERN_WARNING
2362                                 "md/raid:%s: read error on replacement device "
2363                                 "(sector %llu on %s).\n",
2364                                 mdname(conf->mddev),
2365                                 (unsigned long long)s,
2366                                 bdn);
2367                 else if (conf->mddev->degraded >= conf->max_degraded) {
2368                         set_bad = 1;
2369                         printk_ratelimited(
2370                                 KERN_WARNING
2371                                 "md/raid:%s: read error not correctable "
2372                                 "(sector %llu on %s).\n",
2373                                 mdname(conf->mddev),
2374                                 (unsigned long long)s,
2375                                 bdn);
2376                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2377                         /* Oh, no!!! */
2378                         set_bad = 1;
2379                         printk_ratelimited(
2380                                 KERN_WARNING
2381                                 "md/raid:%s: read error NOT corrected!! "
2382                                 "(sector %llu on %s).\n",
2383                                 mdname(conf->mddev),
2384                                 (unsigned long long)s,
2385                                 bdn);
2386                 } else if (atomic_read(&rdev->read_errors)
2387                          > conf->max_nr_stripes)
2388                         printk(KERN_WARNING
2389                                "md/raid:%s: Too many read errors, failing device %s.\n",
2390                                mdname(conf->mddev), bdn);
2391                 else
2392                         retry = 1;
2393                 if (set_bad && test_bit(In_sync, &rdev->flags)
2394                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2395                         retry = 1;
2396                 if (retry)
2397                         if (sh->qd_idx >= 0 && sh->pd_idx == i)
2398                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2399                         else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2400                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2401                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2402                         } else
2403                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2404                 else {
2405                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2406                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2407                         if (!(set_bad
2408                               && test_bit(In_sync, &rdev->flags)
2409                               && rdev_set_badblocks(
2410                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2411                                 md_error(conf->mddev, rdev);
2412                 }
2413         }
2414         rdev_dec_pending(rdev, conf->mddev);
2415         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2416         set_bit(STRIPE_HANDLE, &sh->state);
2417         raid5_release_stripe(sh);
2418 }
2419
2420 static void raid5_end_write_request(struct bio *bi)
2421 {
2422         struct stripe_head *sh = bi->bi_private;
2423         struct r5conf *conf = sh->raid_conf;
2424         int disks = sh->disks, i;
2425         struct md_rdev *uninitialized_var(rdev);
2426         sector_t first_bad;
2427         int bad_sectors;
2428         int replacement = 0;
2429
2430         for (i = 0 ; i < disks; i++) {
2431                 if (bi == &sh->dev[i].req) {
2432                         rdev = conf->disks[i].rdev;
2433                         break;
2434                 }
2435                 if (bi == &sh->dev[i].rreq) {
2436                         rdev = conf->disks[i].replacement;
2437                         if (rdev)
2438                                 replacement = 1;
2439                         else
2440                                 /* rdev was removed and 'replacement'
2441                                  * replaced it.  rdev is not removed
2442                                  * until all requests are finished.
2443                                  */
2444                                 rdev = conf->disks[i].rdev;
2445                         break;
2446                 }
2447         }
2448         pr_debug("end_write_request %llu/%d, count %d, error: %d.\n",
2449                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2450                 bi->bi_error);
2451         if (i == disks) {
2452                 BUG();
2453                 return;
2454         }
2455
2456         if (replacement) {
2457                 if (bi->bi_error)
2458                         md_error(conf->mddev, rdev);
2459                 else if (is_badblock(rdev, sh->sector,
2460                                      STRIPE_SECTORS,
2461                                      &first_bad, &bad_sectors))
2462                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2463         } else {
2464                 if (bi->bi_error) {
2465                         set_bit(STRIPE_DEGRADED, &sh->state);
2466                         set_bit(WriteErrorSeen, &rdev->flags);
2467                         set_bit(R5_WriteError, &sh->dev[i].flags);
2468                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2469                                 set_bit(MD_RECOVERY_NEEDED,
2470                                         &rdev->mddev->recovery);
2471                 } else if (is_badblock(rdev, sh->sector,
2472                                        STRIPE_SECTORS,
2473                                        &first_bad, &bad_sectors)) {
2474                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2475                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2476                                 /* That was a successful write so make
2477                                  * sure it looks like we already did
2478                                  * a re-write.
2479                                  */
2480                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2481                 }
2482         }
2483         rdev_dec_pending(rdev, conf->mddev);
2484
2485         if (sh->batch_head && bi->bi_error && !replacement)
2486                 set_bit(STRIPE_BATCH_ERR, &sh->batch_head->state);
2487
2488         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2489                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2490         set_bit(STRIPE_HANDLE, &sh->state);
2491         raid5_release_stripe(sh);
2492
2493         if (sh->batch_head && sh != sh->batch_head)
2494                 raid5_release_stripe(sh->batch_head);
2495 }
2496
2497 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2498 {
2499         struct r5dev *dev = &sh->dev[i];
2500
2501         bio_init(&dev->req);
2502         dev->req.bi_io_vec = &dev->vec;
2503         dev->req.bi_max_vecs = 1;
2504         dev->req.bi_private = sh;
2505
2506         bio_init(&dev->rreq);
2507         dev->rreq.bi_io_vec = &dev->rvec;
2508         dev->rreq.bi_max_vecs = 1;
2509         dev->rreq.bi_private = sh;
2510
2511         dev->flags = 0;
2512         dev->sector = raid5_compute_blocknr(sh, i, previous);
2513 }
2514
2515 static void error(struct mddev *mddev, struct md_rdev *rdev)
2516 {
2517         char b[BDEVNAME_SIZE];
2518         struct r5conf *conf = mddev->private;
2519         unsigned long flags;
2520         pr_debug("raid456: error called\n");
2521
2522         spin_lock_irqsave(&conf->device_lock, flags);
2523         clear_bit(In_sync, &rdev->flags);
2524         mddev->degraded = calc_degraded(conf);
2525         spin_unlock_irqrestore(&conf->device_lock, flags);
2526         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2527
2528         set_bit(Blocked, &rdev->flags);
2529         set_bit(Faulty, &rdev->flags);
2530         set_bit(MD_CHANGE_DEVS, &mddev->flags);
2531         set_bit(MD_CHANGE_PENDING, &mddev->flags);
2532         printk(KERN_ALERT
2533                "md/raid:%s: Disk failure on %s, disabling device.\n"
2534                "md/raid:%s: Operation continuing on %d devices.\n",
2535                mdname(mddev),
2536                bdevname(rdev->bdev, b),
2537                mdname(mddev),
2538                conf->raid_disks - mddev->degraded);
2539 }
2540
2541 /*
2542  * Input: a 'big' sector number,
2543  * Output: index of the data and parity disk, and the sector # in them.
2544  */
2545 sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2546                               int previous, int *dd_idx,
2547                               struct stripe_head *sh)
2548 {
2549         sector_t stripe, stripe2;
2550         sector_t chunk_number;
2551         unsigned int chunk_offset;
2552         int pd_idx, qd_idx;
2553         int ddf_layout = 0;
2554         sector_t new_sector;
2555         int algorithm = previous ? conf->prev_algo
2556                                  : conf->algorithm;
2557         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2558                                          : conf->chunk_sectors;
2559         int raid_disks = previous ? conf->previous_raid_disks
2560                                   : conf->raid_disks;
2561         int data_disks = raid_disks - conf->max_degraded;
2562
2563         /* First compute the information on this sector */
2564
2565         /*
2566          * Compute the chunk number and the sector offset inside the chunk
2567          */
2568         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2569         chunk_number = r_sector;
2570
2571         /*
2572          * Compute the stripe number
2573          */
2574         stripe = chunk_number;
2575         *dd_idx = sector_div(stripe, data_disks);
2576         stripe2 = stripe;
2577         /*
2578          * Select the parity disk based on the user selected algorithm.
2579          */
2580         pd_idx = qd_idx = -1;
2581         switch(conf->level) {
2582         case 4:
2583                 pd_idx = data_disks;
2584                 break;
2585         case 5:
2586                 switch (algorithm) {
2587                 case ALGORITHM_LEFT_ASYMMETRIC:
2588                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2589                         if (*dd_idx >= pd_idx)
2590                                 (*dd_idx)++;
2591                         break;
2592                 case ALGORITHM_RIGHT_ASYMMETRIC:
2593                         pd_idx = sector_div(stripe2, raid_disks);
2594                         if (*dd_idx >= pd_idx)
2595                                 (*dd_idx)++;
2596                         break;
2597                 case ALGORITHM_LEFT_SYMMETRIC:
2598                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2599                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2600                         break;
2601                 case ALGORITHM_RIGHT_SYMMETRIC:
2602                         pd_idx = sector_div(stripe2, raid_disks);
2603                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2604                         break;
2605                 case ALGORITHM_PARITY_0:
2606                         pd_idx = 0;
2607                         (*dd_idx)++;
2608                         break;
2609                 case ALGORITHM_PARITY_N:
2610                         pd_idx = data_disks;
2611                         break;
2612                 default:
2613                         BUG();
2614                 }
2615                 break;
2616         case 6:
2617
2618                 switch (algorithm) {
2619                 case ALGORITHM_LEFT_ASYMMETRIC:
2620                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2621                         qd_idx = pd_idx + 1;
2622                         if (pd_idx == raid_disks-1) {
2623                                 (*dd_idx)++;    /* Q D D D P */
2624                                 qd_idx = 0;
2625                         } else if (*dd_idx >= pd_idx)
2626                                 (*dd_idx) += 2; /* D D P Q D */
2627                         break;
2628                 case ALGORITHM_RIGHT_ASYMMETRIC:
2629                         pd_idx = sector_div(stripe2, raid_disks);
2630                         qd_idx = pd_idx + 1;
2631                         if (pd_idx == raid_disks-1) {
2632                                 (*dd_idx)++;    /* Q D D D P */
2633                                 qd_idx = 0;
2634                         } else if (*dd_idx >= pd_idx)
2635                                 (*dd_idx) += 2; /* D D P Q D */
2636                         break;
2637                 case ALGORITHM_LEFT_SYMMETRIC:
2638                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2639                         qd_idx = (pd_idx + 1) % raid_disks;
2640                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2641                         break;
2642                 case ALGORITHM_RIGHT_SYMMETRIC:
2643                         pd_idx = sector_div(stripe2, raid_disks);
2644                         qd_idx = (pd_idx + 1) % raid_disks;
2645                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2646                         break;
2647
2648                 case ALGORITHM_PARITY_0:
2649                         pd_idx = 0;
2650                         qd_idx = 1;
2651                         (*dd_idx) += 2;
2652                         break;
2653                 case ALGORITHM_PARITY_N:
2654                         pd_idx = data_disks;
2655                         qd_idx = data_disks + 1;
2656                         break;
2657
2658                 case ALGORITHM_ROTATING_ZERO_RESTART:
2659                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2660                          * of blocks for computing Q is different.
2661                          */
2662                         pd_idx = sector_div(stripe2, raid_disks);
2663                         qd_idx = pd_idx + 1;
2664                         if (pd_idx == raid_disks-1) {
2665                                 (*dd_idx)++;    /* Q D D D P */
2666                                 qd_idx = 0;
2667                         } else if (*dd_idx >= pd_idx)
2668                                 (*dd_idx) += 2; /* D D P Q D */
2669                         ddf_layout = 1;
2670                         break;
2671
2672                 case ALGORITHM_ROTATING_N_RESTART:
2673                         /* Same a left_asymmetric, by first stripe is
2674                          * D D D P Q  rather than
2675                          * Q D D D P
2676                          */
2677                         stripe2 += 1;
2678                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2679                         qd_idx = pd_idx + 1;
2680                         if (pd_idx == raid_disks-1) {
2681                                 (*dd_idx)++;    /* Q D D D P */
2682                                 qd_idx = 0;
2683                         } else if (*dd_idx >= pd_idx)
2684                                 (*dd_idx) += 2; /* D D P Q D */
2685                         ddf_layout = 1;
2686                         break;
2687
2688                 case ALGORITHM_ROTATING_N_CONTINUE:
2689                         /* Same as left_symmetric but Q is before P */
2690                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2691                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2692                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2693                         ddf_layout = 1;
2694                         break;
2695
2696                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2697                         /* RAID5 left_asymmetric, with Q on last device */
2698                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2699                         if (*dd_idx >= pd_idx)
2700                                 (*dd_idx)++;
2701                         qd_idx = raid_disks - 1;
2702                         break;
2703
2704                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2705                         pd_idx = sector_div(stripe2, raid_disks-1);
2706                         if (*dd_idx >= pd_idx)
2707                                 (*dd_idx)++;
2708                         qd_idx = raid_disks - 1;
2709                         break;
2710
2711                 case ALGORITHM_LEFT_SYMMETRIC_6:
2712                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2713                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2714                         qd_idx = raid_disks - 1;
2715                         break;
2716
2717                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2718                         pd_idx = sector_div(stripe2, raid_disks-1);
2719                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2720                         qd_idx = raid_disks - 1;
2721                         break;
2722
2723                 case ALGORITHM_PARITY_0_6:
2724                         pd_idx = 0;
2725                         (*dd_idx)++;
2726                         qd_idx = raid_disks - 1;
2727                         break;
2728
2729                 default:
2730                         BUG();
2731                 }
2732                 break;
2733         }
2734
2735         if (sh) {
2736                 sh->pd_idx = pd_idx;
2737                 sh->qd_idx = qd_idx;
2738                 sh->ddf_layout = ddf_layout;
2739         }
2740         /*
2741          * Finally, compute the new sector number
2742          */
2743         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2744         return new_sector;
2745 }
2746
2747 sector_t raid5_compute_blocknr(struct stripe_head *sh, int i, int previous)
2748 {
2749         struct r5conf *conf = sh->raid_conf;
2750         int raid_disks = sh->disks;
2751         int data_disks = raid_disks - conf->max_degraded;
2752         sector_t new_sector = sh->sector, check;
2753         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2754                                          : conf->chunk_sectors;
2755         int algorithm = previous ? conf->prev_algo
2756                                  : conf->algorithm;
2757         sector_t stripe;
2758         int chunk_offset;
2759         sector_t chunk_number;
2760         int dummy1, dd_idx = i;
2761         sector_t r_sector;
2762         struct stripe_head sh2;
2763
2764         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2765         stripe = new_sector;
2766
2767         if (i == sh->pd_idx)
2768                 return 0;
2769         switch(conf->level) {
2770         case 4: break;
2771         case 5:
2772                 switch (algorithm) {
2773                 case ALGORITHM_LEFT_ASYMMETRIC:
2774                 case ALGORITHM_RIGHT_ASYMMETRIC:
2775                         if (i > sh->pd_idx)
2776                                 i--;
2777                         break;
2778                 case ALGORITHM_LEFT_SYMMETRIC:
2779                 case ALGORITHM_RIGHT_SYMMETRIC:
2780                         if (i < sh->pd_idx)
2781                                 i += raid_disks;
2782                         i -= (sh->pd_idx + 1);
2783                         break;
2784                 case ALGORITHM_PARITY_0:
2785                         i -= 1;
2786                         break;
2787                 case ALGORITHM_PARITY_N:
2788                         break;
2789                 default:
2790                         BUG();
2791                 }
2792                 break;
2793         case 6:
2794                 if (i == sh->qd_idx)
2795                         return 0; /* It is the Q disk */
2796                 switch (algorithm) {
2797                 case ALGORITHM_LEFT_ASYMMETRIC:
2798                 case ALGORITHM_RIGHT_ASYMMETRIC:
2799                 case ALGORITHM_ROTATING_ZERO_RESTART:
2800                 case ALGORITHM_ROTATING_N_RESTART:
2801                         if (sh->pd_idx == raid_disks-1)
2802                                 i--;    /* Q D D D P */
2803                         else if (i > sh->pd_idx)
2804                                 i -= 2; /* D D P Q D */
2805                         break;
2806                 case ALGORITHM_LEFT_SYMMETRIC:
2807                 case ALGORITHM_RIGHT_SYMMETRIC:
2808                         if (sh->pd_idx == raid_disks-1)
2809                                 i--; /* Q D D D P */
2810                         else {
2811                                 /* D D P Q D */
2812                                 if (i < sh->pd_idx)
2813                                         i += raid_disks;
2814                                 i -= (sh->pd_idx + 2);
2815                         }
2816                         break;
2817                 case ALGORITHM_PARITY_0:
2818                         i -= 2;
2819                         break;
2820                 case ALGORITHM_PARITY_N:
2821                         break;
2822                 case ALGORITHM_ROTATING_N_CONTINUE:
2823                         /* Like left_symmetric, but P is before Q */
2824                         if (sh->pd_idx == 0)
2825                                 i--;    /* P D D D Q */
2826                         else {
2827                                 /* D D Q P D */
2828                                 if (i < sh->pd_idx)
2829                                         i += raid_disks;
2830                                 i -= (sh->pd_idx + 1);
2831                         }
2832                         break;
2833                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2834                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2835                         if (i > sh->pd_idx)
2836                                 i--;
2837                         break;
2838                 case ALGORITHM_LEFT_SYMMETRIC_6:
2839                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2840                         if (i < sh->pd_idx)
2841                                 i += data_disks + 1;
2842                         i -= (sh->pd_idx + 1);
2843                         break;
2844                 case ALGORITHM_PARITY_0_6:
2845                         i -= 1;
2846                         break;
2847                 default:
2848                         BUG();
2849                 }
2850                 break;
2851         }
2852
2853         chunk_number = stripe * data_disks + i;
2854         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2855
2856         check = raid5_compute_sector(conf, r_sector,
2857                                      previous, &dummy1, &sh2);
2858         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2859                 || sh2.qd_idx != sh->qd_idx) {
2860                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2861                        mdname(conf->mddev));
2862                 return 0;
2863         }
2864         return r_sector;
2865 }
2866
2867 static void
2868 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2869                          int rcw, int expand)
2870 {
2871         int i, pd_idx = sh->pd_idx, qd_idx = sh->qd_idx, disks = sh->disks;
2872         struct r5conf *conf = sh->raid_conf;
2873         int level = conf->level;
2874
2875         if (rcw) {
2876
2877                 for (i = disks; i--; ) {
2878                         struct r5dev *dev = &sh->dev[i];
2879
2880                         if (dev->towrite) {
2881                                 set_bit(R5_LOCKED, &dev->flags);
2882                                 set_bit(R5_Wantdrain, &dev->flags);
2883                                 if (!expand)
2884                                         clear_bit(R5_UPTODATE, &dev->flags);
2885                                 s->locked++;
2886                         }
2887                 }
2888                 /* if we are not expanding this is a proper write request, and
2889                  * there will be bios with new data to be drained into the
2890                  * stripe cache
2891                  */
2892                 if (!expand) {
2893                         if (!s->locked)
2894                                 /* False alarm, nothing to do */
2895                                 return;
2896                         sh->reconstruct_state = reconstruct_state_drain_run;
2897                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2898                 } else
2899                         sh->reconstruct_state = reconstruct_state_run;
2900
2901                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2902
2903                 if (s->locked + conf->max_degraded == disks)
2904                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2905                                 atomic_inc(&conf->pending_full_writes);
2906         } else {
2907                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2908                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2909                 BUG_ON(level == 6 &&
2910                         (!(test_bit(R5_UPTODATE, &sh->dev[qd_idx].flags) ||
2911                            test_bit(R5_Wantcompute, &sh->dev[qd_idx].flags))));
2912
2913                 for (i = disks; i--; ) {
2914                         struct r5dev *dev = &sh->dev[i];
2915                         if (i == pd_idx || i == qd_idx)
2916                                 continue;
2917
2918                         if (dev->towrite &&
2919                             (test_bit(R5_UPTODATE, &dev->flags) ||
2920                              test_bit(R5_Wantcompute, &dev->flags))) {
2921                                 set_bit(R5_Wantdrain, &dev->flags);
2922                                 set_bit(R5_LOCKED, &dev->flags);
2923                                 clear_bit(R5_UPTODATE, &dev->flags);
2924                                 s->locked++;
2925                         }
2926                 }
2927                 if (!s->locked)
2928                         /* False alarm - nothing to do */
2929                         return;
2930                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2931                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2932                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2933                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2934         }
2935
2936         /* keep the parity disk(s) locked while asynchronous operations
2937          * are in flight
2938          */
2939         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2940         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2941         s->locked++;
2942
2943         if (level == 6) {
2944                 int qd_idx = sh->qd_idx;
2945                 struct r5dev *dev = &sh->dev[qd_idx];
2946
2947                 set_bit(R5_LOCKED, &dev->flags);
2948                 clear_bit(R5_UPTODATE, &dev->flags);
2949                 s->locked++;
2950         }
2951
2952         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2953                 __func__, (unsigned long long)sh->sector,
2954                 s->locked, s->ops_request);
2955 }
2956
2957 /*
2958  * Each stripe/dev can have one or more bion attached.
2959  * toread/towrite point to the first in a chain.
2960  * The bi_next chain must be in order.
2961  */
2962 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx,
2963                           int forwrite, int previous)
2964 {
2965         struct bio **bip;
2966         struct r5conf *conf = sh->raid_conf;
2967         int firstwrite=0;
2968
2969         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2970                 (unsigned long long)bi->bi_iter.bi_sector,
2971                 (unsigned long long)sh->sector);
2972
2973         /*
2974          * If several bio share a stripe. The bio bi_phys_segments acts as a
2975          * reference count to avoid race. The reference count should already be
2976          * increased before this function is called (for example, in
2977          * make_request()), so other bio sharing this stripe will not free the
2978          * stripe. If a stripe is owned by one stripe, the stripe lock will
2979          * protect it.
2980          */
2981         spin_lock_irq(&sh->stripe_lock);
2982         /* Don't allow new IO added to stripes in batch list */
2983         if (sh->batch_head)
2984                 goto overlap;
2985         if (forwrite) {
2986                 bip = &sh->dev[dd_idx].towrite;
2987                 if (*bip == NULL)
2988                         firstwrite = 1;
2989         } else
2990                 bip = &sh->dev[dd_idx].toread;
2991         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
2992                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
2993                         goto overlap;
2994                 bip = & (*bip)->bi_next;
2995         }
2996         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
2997                 goto overlap;
2998
2999         if (!forwrite || previous)
3000                 clear_bit(STRIPE_BATCH_READY, &sh->state);
3001
3002         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
3003         if (*bip)
3004                 bi->bi_next = *bip;
3005         *bip = bi;
3006         raid5_inc_bi_active_stripes(bi);
3007
3008         if (forwrite) {
3009                 /* check if page is covered */
3010                 sector_t sector = sh->dev[dd_idx].sector;
3011                 for (bi=sh->dev[dd_idx].towrite;
3012                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
3013                              bi && bi->bi_iter.bi_sector <= sector;
3014                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
3015                         if (bio_end_sector(bi) >= sector)
3016                                 sector = bio_end_sector(bi);
3017                 }
3018                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
3019                         if (!test_and_set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags))
3020                                 sh->overwrite_disks++;
3021         }
3022
3023         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
3024                 (unsigned long long)(*bip)->bi_iter.bi_sector,
3025                 (unsigned long long)sh->sector, dd_idx);
3026
3027         if (conf->mddev->bitmap && firstwrite) {
3028                 /* Cannot hold spinlock over bitmap_startwrite,
3029                  * but must ensure this isn't added to a batch until
3030                  * we have added to the bitmap and set bm_seq.
3031                  * So set STRIPE_BITMAP_PENDING to prevent
3032                  * batching.
3033                  * If multiple add_stripe_bio() calls race here they
3034                  * much all set STRIPE_BITMAP_PENDING.  So only the first one
3035                  * to complete "bitmap_startwrite" gets to set
3036                  * STRIPE_BIT_DELAY.  This is important as once a stripe
3037                  * is added to a batch, STRIPE_BIT_DELAY cannot be changed
3038                  * any more.
3039                  */
3040                 set_bit(STRIPE_BITMAP_PENDING, &sh->state);
3041                 spin_unlock_irq(&sh->stripe_lock);
3042                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
3043                                   STRIPE_SECTORS, 0);
3044                 spin_lock_irq(&sh->stripe_lock);
3045                 clear_bit(STRIPE_BITMAP_PENDING, &sh->state);
3046                 if (!sh->batch_head) {
3047                         sh->bm_seq = conf->seq_flush+1;
3048                         set_bit(STRIPE_BIT_DELAY, &sh->state);
3049                 }
3050         }
3051         spin_unlock_irq(&sh->stripe_lock);
3052
3053         if (stripe_can_batch(sh))
3054                 stripe_add_to_batch_list(conf, sh);
3055         return 1;
3056
3057  overlap:
3058         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
3059         spin_unlock_irq(&sh->stripe_lock);
3060         return 0;
3061 }
3062
3063 static void end_reshape(struct r5conf *conf);
3064
3065 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
3066                             struct stripe_head *sh)
3067 {
3068         int sectors_per_chunk =
3069                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
3070         int dd_idx;
3071         int chunk_offset = sector_div(stripe, sectors_per_chunk);
3072         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
3073
3074         raid5_compute_sector(conf,
3075                              stripe * (disks - conf->max_degraded)
3076                              *sectors_per_chunk + chunk_offset,
3077                              previous,
3078                              &dd_idx, sh);
3079 }
3080
3081 static void
3082 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
3083                                 struct stripe_head_state *s, int disks,
3084                                 struct bio_list *return_bi)
3085 {
3086         int i;
3087         BUG_ON(sh->batch_head);
3088         for (i = disks; i--; ) {
3089                 struct bio *bi;
3090                 int bitmap_end = 0;
3091
3092                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
3093                         struct md_rdev *rdev;
3094                         rcu_read_lock();
3095                         rdev = rcu_dereference(conf->disks[i].rdev);
3096                         if (rdev && test_bit(In_sync, &rdev->flags))
3097                                 atomic_inc(&rdev->nr_pending);
3098                         else
3099                                 rdev = NULL;
3100                         rcu_read_unlock();
3101                         if (rdev) {
3102                                 if (!rdev_set_badblocks(
3103                                             rdev,
3104                                             sh->sector,
3105                                             STRIPE_SECTORS, 0))
3106                                         md_error(conf->mddev, rdev);
3107                                 rdev_dec_pending(rdev, conf->mddev);
3108                         }
3109                 }
3110                 spin_lock_irq(&sh->stripe_lock);
3111                 /* fail all writes first */
3112                 bi = sh->dev[i].towrite;
3113                 sh->dev[i].towrite = NULL;
3114                 sh->overwrite_disks = 0;
3115                 spin_unlock_irq(&sh->stripe_lock);
3116                 if (bi)
3117                         bitmap_end = 1;
3118
3119                 r5l_stripe_write_finished(sh);
3120
3121                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3122                         wake_up(&conf->wait_for_overlap);
3123
3124                 while (bi && bi->bi_iter.bi_sector <
3125                         sh->dev[i].sector + STRIPE_SECTORS) {
3126                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
3127
3128                         bi->bi_error = -EIO;
3129                         if (!raid5_dec_bi_active_stripes(bi)) {
3130                                 md_write_end(conf->mddev);
3131                                 bio_list_add(return_bi, bi);
3132                         }
3133                         bi = nextbi;
3134                 }
3135                 if (bitmap_end)
3136                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3137                                 STRIPE_SECTORS, 0, 0);
3138                 bitmap_end = 0;
3139                 /* and fail all 'written' */
3140                 bi = sh->dev[i].written;
3141                 sh->dev[i].written = NULL;
3142                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
3143                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
3144                         sh->dev[i].page = sh->dev[i].orig_page;
3145                 }
3146
3147                 if (bi) bitmap_end = 1;
3148                 while (bi && bi->bi_iter.bi_sector <
3149                        sh->dev[i].sector + STRIPE_SECTORS) {
3150                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
3151
3152                         bi->bi_error = -EIO;
3153                         if (!raid5_dec_bi_active_stripes(bi)) {
3154                                 md_write_end(conf->mddev);
3155                                 bio_list_add(return_bi, bi);
3156                         }
3157                         bi = bi2;
3158                 }
3159
3160                 /* fail any reads if this device is non-operational and
3161                  * the data has not reached the cache yet.
3162                  */
3163                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
3164                     s->failed > conf->max_degraded &&
3165                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
3166                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
3167                         spin_lock_irq(&sh->stripe_lock);
3168                         bi = sh->dev[i].toread;
3169                         sh->dev[i].toread = NULL;
3170                         spin_unlock_irq(&sh->stripe_lock);
3171                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
3172                                 wake_up(&conf->wait_for_overlap);
3173                         if (bi)
3174                                 s->to_read--;
3175                         while (bi && bi->bi_iter.bi_sector <
3176                                sh->dev[i].sector + STRIPE_SECTORS) {
3177                                 struct bio *nextbi =
3178                                         r5_next_bio(bi, sh->dev[i].sector);
3179
3180                                 bi->bi_error = -EIO;
3181                                 if (!raid5_dec_bi_active_stripes(bi))
3182                                         bio_list_add(return_bi, bi);
3183                                 bi = nextbi;
3184                         }
3185                 }
3186                 if (bitmap_end)
3187                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3188                                         STRIPE_SECTORS, 0, 0);
3189                 /* If we were in the middle of a write the parity block might
3190                  * still be locked - so just clear all R5_LOCKED flags
3191                  */
3192                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
3193         }
3194         s->to_write = 0;
3195         s->written = 0;
3196
3197         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3198                 if (atomic_dec_and_test(&conf->pending_full_writes))
3199                         md_wakeup_thread(conf->mddev->thread);
3200 }
3201
3202 static void
3203 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
3204                    struct stripe_head_state *s)
3205 {
3206         int abort = 0;
3207         int i;
3208
3209         BUG_ON(sh->batch_head);
3210         clear_bit(STRIPE_SYNCING, &sh->state);
3211         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3212                 wake_up(&conf->wait_for_overlap);
3213         s->syncing = 0;
3214         s->replacing = 0;
3215         /* There is nothing more to do for sync/check/repair.
3216          * Don't even need to abort as that is handled elsewhere
3217          * if needed, and not always wanted e.g. if there is a known
3218          * bad block here.
3219          * For recover/replace we need to record a bad block on all
3220          * non-sync devices, or abort the recovery
3221          */
3222         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
3223                 /* During recovery devices cannot be removed, so
3224                  * locking and refcounting of rdevs is not needed
3225                  */
3226                 for (i = 0; i < conf->raid_disks; i++) {
3227                         struct md_rdev *rdev = conf->disks[i].rdev;
3228                         if (rdev
3229                             && !test_bit(Faulty, &rdev->flags)
3230                             && !test_bit(In_sync, &rdev->flags)
3231                             && !rdev_set_badblocks(rdev, sh->sector,
3232                                                    STRIPE_SECTORS, 0))
3233                                 abort = 1;
3234                         rdev = conf->disks[i].replacement;
3235                         if (rdev
3236                             && !test_bit(Faulty, &rdev->flags)
3237                             && !test_bit(In_sync, &rdev->flags)
3238                             && !rdev_set_badblocks(rdev, sh->sector,
3239                                                    STRIPE_SECTORS, 0))
3240                                 abort = 1;
3241                 }
3242                 if (abort)
3243                         conf->recovery_disabled =
3244                                 conf->mddev->recovery_disabled;
3245         }
3246         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
3247 }
3248
3249 static int want_replace(struct stripe_head *sh, int disk_idx)
3250 {
3251         struct md_rdev *rdev;
3252         int rv = 0;
3253         /* Doing recovery so rcu locking not required */
3254         rdev = sh->raid_conf->disks[disk_idx].replacement;
3255         if (rdev
3256             && !test_bit(Faulty, &rdev->flags)
3257             && !test_bit(In_sync, &rdev->flags)
3258             && (rdev->recovery_offset <= sh->sector
3259                 || rdev->mddev->recovery_cp <= sh->sector))
3260                 rv = 1;
3261
3262         return rv;
3263 }
3264
3265 /* fetch_block - checks the given member device to see if its data needs
3266  * to be read or computed to satisfy a request.
3267  *
3268  * Returns 1 when no more member devices need to be checked, otherwise returns
3269  * 0 to tell the loop in handle_stripe_fill to continue
3270  */
3271
3272 static int need_this_block(struct stripe_head *sh, struct stripe_head_state *s,
3273                            int disk_idx, int disks)
3274 {
3275         struct r5dev *dev = &sh->dev[disk_idx];
3276         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
3277                                   &sh->dev[s->failed_num[1]] };
3278         int i;
3279
3280
3281         if (test_bit(R5_LOCKED, &dev->flags) ||
3282             test_bit(R5_UPTODATE, &dev->flags))
3283                 /* No point reading this as we already have it or have
3284                  * decided to get it.
3285                  */
3286                 return 0;
3287
3288         if (dev->toread ||
3289             (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)))
3290                 /* We need this block to directly satisfy a request */
3291                 return 1;
3292
3293         if (s->syncing || s->expanding ||
3294             (s->replacing && want_replace(sh, disk_idx)))
3295                 /* When syncing, or expanding we read everything.
3296                  * When replacing, we need the replaced block.
3297                  */
3298                 return 1;
3299
3300         if ((s->failed >= 1 && fdev[0]->toread) ||
3301             (s->failed >= 2 && fdev[1]->toread))
3302                 /* If we want to read from a failed device, then
3303                  * we need to actually read every other device.
3304                  */
3305                 return 1;
3306
3307         /* Sometimes neither read-modify-write nor reconstruct-write
3308          * cycles can work.  In those cases we read every block we
3309          * can.  Then the parity-update is certain to have enough to
3310          * work with.
3311          * This can only be a problem when we need to write something,
3312          * and some device has failed.  If either of those tests
3313          * fail we need look no further.
3314          */
3315         if (!s->failed || !s->to_write)
3316                 return 0;
3317
3318         if (test_bit(R5_Insync, &dev->flags) &&
3319             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3320                 /* Pre-reads at not permitted until after short delay
3321                  * to gather multiple requests.  However if this
3322                  * device is no Insync, the block could only be be computed
3323                  * and there is no need to delay that.
3324                  */
3325                 return 0;
3326
3327         for (i = 0; i < s->failed && i < 2; i++) {
3328                 if (fdev[i]->towrite &&
3329                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3330                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3331                         /* If we have a partial write to a failed
3332                          * device, then we will need to reconstruct
3333                          * the content of that device, so all other
3334                          * devices must be read.
3335                          */
3336                         return 1;
3337         }
3338
3339         /* If we are forced to do a reconstruct-write, either because
3340          * the current RAID6 implementation only supports that, or
3341          * or because parity cannot be trusted and we are currently
3342          * recovering it, there is extra need to be careful.
3343          * If one of the devices that we would need to read, because
3344          * it is not being overwritten (and maybe not written at all)
3345          * is missing/faulty, then we need to read everything we can.
3346          */
3347         if (sh->raid_conf->level != 6 &&
3348             sh->raid_conf->rmw_level != PARITY_DISABLE_RMW &&
3349             sh->sector < sh->raid_conf->mddev->recovery_cp)
3350                 /* reconstruct-write isn't being forced */
3351                 return 0;
3352         for (i = 0; i < s->failed && i < 2; i++) {
3353                 if (s->failed_num[i] != sh->pd_idx &&
3354                     s->failed_num[i] != sh->qd_idx &&
3355                     !test_bit(R5_UPTODATE, &fdev[i]->flags) &&
3356                     !test_bit(R5_OVERWRITE, &fdev[i]->flags))
3357                         return 1;
3358         }
3359
3360         return 0;
3361 }
3362
3363 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
3364                        int disk_idx, int disks)
3365 {
3366         struct r5dev *dev = &sh->dev[disk_idx];
3367
3368         /* is the data in this block needed, and can we get it? */
3369         if (need_this_block(sh, s, disk_idx, disks)) {
3370                 /* we would like to get this block, possibly by computing it,
3371                  * otherwise read it if the backing disk is insync
3372                  */
3373                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
3374                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
3375                 BUG_ON(sh->batch_head);
3376
3377                 /*
3378                  * In the raid6 case if the only non-uptodate disk is P
3379                  * then we already trusted P to compute the other failed
3380                  * drives. It is safe to compute rather than re-read P.
3381                  * In other cases we only compute blocks from failed
3382                  * devices, otherwise check/repair might fail to detect
3383                  * a real inconsistency.
3384                  */
3385
3386                 if ((s->uptodate == disks - 1) &&
3387                     ((sh->qd_idx >= 0 && sh->pd_idx == disk_idx) ||
3388                     (s->failed && (disk_idx == s->failed_num[0] ||
3389                                    disk_idx == s->failed_num[1])))) {
3390                         /* have disk failed, and we're requested to fetch it;
3391                          * do compute it
3392                          */
3393                         pr_debug("Computing stripe %llu block %d\n",
3394                                (unsigned long long)sh->sector, disk_idx);
3395                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3396                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3397                         set_bit(R5_Wantcompute, &dev->flags);
3398                         sh->ops.target = disk_idx;
3399                         sh->ops.target2 = -1; /* no 2nd target */
3400                         s->req_compute = 1;
3401                         /* Careful: from this point on 'uptodate' is in the eye
3402                          * of raid_run_ops which services 'compute' operations
3403                          * before writes. R5_Wantcompute flags a block that will
3404                          * be R5_UPTODATE by the time it is needed for a
3405                          * subsequent operation.
3406                          */
3407                         s->uptodate++;
3408                         return 1;
3409                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
3410                         /* Computing 2-failure is *very* expensive; only
3411                          * do it if failed >= 2
3412                          */
3413                         int other;
3414                         for (other = disks; other--; ) {
3415                                 if (other == disk_idx)
3416                                         continue;
3417                                 if (!test_bit(R5_UPTODATE,
3418                                       &sh->dev[other].flags))
3419                                         break;
3420                         }
3421                         BUG_ON(other < 0);
3422                         pr_debug("Computing stripe %llu blocks %d,%d\n",
3423                                (unsigned long long)sh->sector,
3424                                disk_idx, other);
3425                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3426                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3427                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
3428                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
3429                         sh->ops.target = disk_idx;
3430                         sh->ops.target2 = other;
3431                         s->uptodate += 2;
3432                         s->req_compute = 1;
3433                         return 1;
3434                 } else if (test_bit(R5_Insync, &dev->flags)) {
3435                         set_bit(R5_LOCKED, &dev->flags);
3436                         set_bit(R5_Wantread, &dev->flags);
3437                         s->locked++;
3438                         pr_debug("Reading block %d (sync=%d)\n",
3439                                 disk_idx, s->syncing);
3440                 }
3441         }
3442
3443         return 0;
3444 }
3445
3446 /**
3447  * handle_stripe_fill - read or compute data to satisfy pending requests.
3448  */
3449 static void handle_stripe_fill(struct stripe_head *sh,
3450                                struct stripe_head_state *s,
3451                                int disks)
3452 {
3453         int i;
3454
3455         /* look for blocks to read/compute, skip this if a compute
3456          * is already in flight, or if the stripe contents are in the
3457          * midst of changing due to a write
3458          */
3459         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3460             !sh->reconstruct_state)
3461                 for (i = disks; i--; )
3462                         if (fetch_block(sh, s, i, disks))
3463                                 break;
3464         set_bit(STRIPE_HANDLE, &sh->state);
3465 }
3466
3467 static void break_stripe_batch_list(struct stripe_head *head_sh,
3468                                     unsigned long handle_flags);
3469 /* handle_stripe_clean_event
3470  * any written block on an uptodate or failed drive can be returned.
3471  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3472  * never LOCKED, so we don't need to test 'failed' directly.
3473  */
3474 static void handle_stripe_clean_event(struct r5conf *conf,
3475         struct stripe_head *sh, int disks, struct bio_list *return_bi)
3476 {
3477         int i;
3478         struct r5dev *dev;
3479         int discard_pending = 0;
3480         struct stripe_head *head_sh = sh;
3481         bool do_endio = false;
3482
3483         for (i = disks; i--; )
3484                 if (sh->dev[i].written) {
3485                         dev = &sh->dev[i];
3486                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3487                             (test_bit(R5_UPTODATE, &dev->flags) ||
3488                              test_bit(R5_Discard, &dev->flags) ||
3489                              test_bit(R5_SkipCopy, &dev->flags))) {
3490                                 /* We can return any write requests */
3491                                 struct bio *wbi, *wbi2;
3492                                 pr_debug("Return write for disc %d\n", i);
3493                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3494                                         clear_bit(R5_UPTODATE, &dev->flags);
3495                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3496                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3497                                 }
3498                                 do_endio = true;
3499
3500 returnbi:
3501                                 dev->page = dev->orig_page;
3502                                 wbi = dev->written;
3503                                 dev->written = NULL;
3504                                 while (wbi && wbi->bi_iter.bi_sector <
3505                                         dev->sector + STRIPE_SECTORS) {
3506                                         wbi2 = r5_next_bio(wbi, dev->sector);
3507                                         if (!raid5_dec_bi_active_stripes(wbi)) {
3508                                                 md_write_end(conf->mddev);
3509                                                 bio_list_add(return_bi, wbi);
3510                                         }
3511                                         wbi = wbi2;
3512                                 }
3513                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3514                                                 STRIPE_SECTORS,
3515                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3516                                                 0);
3517                                 if (head_sh->batch_head) {
3518                                         sh = list_first_entry(&sh->batch_list,
3519                                                               struct stripe_head,
3520                                                               batch_list);
3521                                         if (sh != head_sh) {
3522                                                 dev = &sh->dev[i];
3523                                                 goto returnbi;
3524                                         }
3525                                 }
3526                                 sh = head_sh;
3527                                 dev = &sh->dev[i];
3528                         } else if (test_bit(R5_Discard, &dev->flags))
3529                                 discard_pending = 1;
3530                         WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
3531                         WARN_ON(dev->page != dev->orig_page);
3532                 }
3533
3534         r5l_stripe_write_finished(sh);
3535
3536         if (!discard_pending &&
3537             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3538                 int hash;
3539                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3540                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3541                 if (sh->qd_idx >= 0) {
3542                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3543                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3544                 }
3545                 /* now that discard is done we can proceed with any sync */
3546                 clear_bit(STRIPE_DISCARD, &sh->state);
3547                 /*
3548                  * SCSI discard will change some bio fields and the stripe has
3549                  * no updated data, so remove it from hash list and the stripe
3550                  * will be reinitialized
3551                  */
3552 unhash:
3553                 hash = sh->hash_lock_index;
3554                 spin_lock_irq(conf->hash_locks + hash);
3555                 remove_hash(sh);
3556                 spin_unlock_irq(conf->hash_locks + hash);
3557                 if (head_sh->batch_head) {
3558                         sh = list_first_entry(&sh->batch_list,
3559                                               struct stripe_head, batch_list);
3560                         if (sh != head_sh)
3561                                         goto unhash;
3562                 }
3563                 sh = head_sh;
3564
3565                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3566                         set_bit(STRIPE_HANDLE, &sh->state);
3567
3568         }
3569
3570         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3571                 if (atomic_dec_and_test(&conf->pending_full_writes))
3572                         md_wakeup_thread(conf->mddev->thread);
3573
3574         if (head_sh->batch_head && do_endio)
3575                 break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
3576 }
3577
3578 static void handle_stripe_dirtying(struct r5conf *conf,
3579                                    struct stripe_head *sh,
3580                                    struct stripe_head_state *s,
3581                                    int disks)
3582 {
3583         int rmw = 0, rcw = 0, i;
3584         sector_t recovery_cp = conf->mddev->recovery_cp;
3585
3586         /* Check whether resync is now happening or should start.
3587          * If yes, then the array is dirty (after unclean shutdown or
3588          * initial creation), so parity in some stripes might be inconsistent.
3589          * In this case, we need to always do reconstruct-write, to ensure
3590          * that in case of drive failure or read-error correction, we
3591          * generate correct data from the parity.
3592          */
3593         if (conf->rmw_level == PARITY_DISABLE_RMW ||
3594             (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
3595              s->failed == 0)) {
3596                 /* Calculate the real rcw later - for now make it
3597                  * look like rcw is cheaper
3598                  */
3599                 rcw = 1; rmw = 2;
3600                 pr_debug("force RCW rmw_level=%u, recovery_cp=%llu sh->sector=%llu\n",
3601                          conf->rmw_level, (unsigned long long)recovery_cp,
3602                          (unsigned long long)sh->sector);
3603         } else for (i = disks; i--; ) {
3604                 /* would I have to read this buffer for read_modify_write */
3605                 struct r5dev *dev = &sh->dev[i];
3606                 if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3607                     !test_bit(R5_LOCKED, &dev->flags) &&
3608                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3609                       test_bit(R5_Wantcompute, &dev->flags))) {
3610                         if (test_bit(R5_Insync, &dev->flags))
3611                                 rmw++;
3612                         else
3613                                 rmw += 2*disks;  /* cannot read it */
3614                 }
3615                 /* Would I have to read this buffer for reconstruct_write */
3616                 if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3617                     i != sh->pd_idx && i != sh->qd_idx &&
3618                     !test_bit(R5_LOCKED, &dev->flags) &&
3619                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3620                     test_bit(R5_Wantcompute, &dev->flags))) {
3621                         if (test_bit(R5_Insync, &dev->flags))
3622                                 rcw++;
3623                         else
3624                                 rcw += 2*disks;
3625                 }
3626         }
3627         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3628                 (unsigned long long)sh->sector, rmw, rcw);
3629         set_bit(STRIPE_HANDLE, &sh->state);
3630         if ((rmw < rcw || (rmw == rcw && conf->rmw_level == PARITY_ENABLE_RMW)) && rmw > 0) {
3631                 /* prefer read-modify-write, but need to get some data */
3632                 if (conf->mddev->queue)
3633                         blk_add_trace_msg(conf->mddev->queue,
3634                                           "raid5 rmw %llu %d",
3635                                           (unsigned long long)sh->sector, rmw);
3636                 for (i = disks; i--; ) {
3637                         struct r5dev *dev = &sh->dev[i];
3638                         if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx) &&
3639                             !test_bit(R5_LOCKED, &dev->flags) &&
3640                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3641                             test_bit(R5_Wantcompute, &dev->flags)) &&
3642                             test_bit(R5_Insync, &dev->flags)) {
3643                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3644                                              &sh->state)) {
3645                                         pr_debug("Read_old block %d for r-m-w\n",
3646                                                  i);
3647                                         set_bit(R5_LOCKED, &dev->flags);
3648                                         set_bit(R5_Wantread, &dev->flags);
3649                                         s->locked++;
3650                                 } else {
3651                                         set_bit(STRIPE_DELAYED, &sh->state);
3652                                         set_bit(STRIPE_HANDLE, &sh->state);
3653                                 }
3654                         }
3655                 }
3656         }
3657         if ((rcw < rmw || (rcw == rmw && conf->rmw_level != PARITY_ENABLE_RMW)) && rcw > 0) {
3658                 /* want reconstruct write, but need to get some data */
3659                 int qread =0;
3660                 rcw = 0;
3661                 for (i = disks; i--; ) {
3662                         struct r5dev *dev = &sh->dev[i];
3663                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3664                             i != sh->pd_idx && i != sh->qd_idx &&
3665                             !test_bit(R5_LOCKED, &dev->flags) &&
3666                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3667                               test_bit(R5_Wantcompute, &dev->flags))) {
3668                                 rcw++;
3669                                 if (test_bit(R5_Insync, &dev->flags) &&
3670                                     test_bit(STRIPE_PREREAD_ACTIVE,
3671                                              &sh->state)) {
3672                                         pr_debug("Read_old block "
3673                                                 "%d for Reconstruct\n", i);
3674                                         set_bit(R5_LOCKED, &dev->flags);
3675                                         set_bit(R5_Wantread, &dev->flags);
3676                                         s->locked++;
3677                                         qread++;
3678                                 } else {
3679                                         set_bit(STRIPE_DELAYED, &sh->state);
3680                                         set_bit(STRIPE_HANDLE, &sh->state);
3681                                 }
3682                         }
3683                 }
3684                 if (rcw && conf->mddev->queue)
3685                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3686                                           (unsigned long long)sh->sector,
3687                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3688         }
3689
3690         if (rcw > disks && rmw > disks &&
3691             !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3692                 set_bit(STRIPE_DELAYED, &sh->state);
3693
3694         /* now if nothing is locked, and if we have enough data,
3695          * we can start a write request
3696          */
3697         /* since handle_stripe can be called at any time we need to handle the
3698          * case where a compute block operation has been submitted and then a
3699          * subsequent call wants to start a write request.  raid_run_ops only
3700          * handles the case where compute block and reconstruct are requested
3701          * simultaneously.  If this is not the case then new writes need to be
3702          * held off until the compute completes.
3703          */
3704         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3705             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3706             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3707                 schedule_reconstruction(sh, s, rcw == 0, 0);
3708 }
3709
3710 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3711                                 struct stripe_head_state *s, int disks)
3712 {
3713         struct r5dev *dev = NULL;
3714
3715         BUG_ON(sh->batch_head);
3716         set_bit(STRIPE_HANDLE, &sh->state);
3717
3718         switch (sh->check_state) {
3719         case check_state_idle:
3720                 /* start a new check operation if there are no failures */
3721                 if (s->failed == 0) {
3722                         BUG_ON(s->uptodate != disks);
3723                         sh->check_state = check_state_run;
3724                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3725                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3726                         s->uptodate--;
3727                         break;
3728                 }
3729                 dev = &sh->dev[s->failed_num[0]];
3730                 /* fall through */
3731         case check_state_compute_result:
3732                 sh->check_state = check_state_idle;
3733                 if (!dev)
3734                         dev = &sh->dev[sh->pd_idx];
3735
3736                 /* check that a write has not made the stripe insync */
3737                 if (test_bit(STRIPE_INSYNC, &sh->state))
3738                         break;
3739
3740                 /* either failed parity check, or recovery is happening */
3741                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3742                 BUG_ON(s->uptodate != disks);
3743
3744                 set_bit(R5_LOCKED, &dev->flags);
3745                 s->locked++;
3746                 set_bit(R5_Wantwrite, &dev->flags);
3747
3748                 clear_bit(STRIPE_DEGRADED, &sh->state);
3749                 set_bit(STRIPE_INSYNC, &sh->state);
3750                 break;
3751         case check_state_run:
3752                 break; /* we will be called again upon completion */
3753         case check_state_check_result:
3754                 sh->check_state = check_state_idle;
3755
3756                 /* if a failure occurred during the check operation, leave
3757                  * STRIPE_INSYNC not set and let the stripe be handled again
3758                  */
3759                 if (s->failed)
3760                         break;
3761
3762                 /* handle a successful check operation, if parity is correct
3763                  * we are done.  Otherwise update the mismatch count and repair
3764                  * parity if !MD_RECOVERY_CHECK
3765                  */
3766                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3767                         /* parity is correct (on disc,
3768                          * not in buffer any more)
3769                          */
3770                         set_bit(STRIPE_INSYNC, &sh->state);
3771                 else {
3772                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3773                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3774                                 /* don't try to repair!! */
3775                                 set_bit(STRIPE_INSYNC, &sh->state);
3776                         else {
3777                                 sh->check_state = check_state_compute_run;
3778                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3779                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3780                                 set_bit(R5_Wantcompute,
3781                                         &sh->dev[sh->pd_idx].flags);
3782                                 sh->ops.target = sh->pd_idx;
3783                                 sh->ops.target2 = -1;
3784                                 s->uptodate++;
3785                         }
3786                 }
3787                 break;
3788         case check_state_compute_run:
3789                 break;
3790         default:
3791                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3792                        __func__, sh->check_state,
3793                        (unsigned long long) sh->sector);
3794                 BUG();
3795         }
3796 }
3797
3798 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3799                                   struct stripe_head_state *s,
3800                                   int disks)
3801 {
3802         int pd_idx = sh->pd_idx;
3803         int qd_idx = sh->qd_idx;
3804         struct r5dev *dev;
3805
3806         BUG_ON(sh->batch_head);
3807         set_bit(STRIPE_HANDLE, &sh->state);
3808
3809         BUG_ON(s->failed > 2);
3810
3811         /* Want to check and possibly repair P and Q.
3812          * However there could be one 'failed' device, in which
3813          * case we can only check one of them, possibly using the
3814          * other to generate missing data
3815          */
3816
3817         switch (sh->check_state) {
3818         case check_state_idle:
3819                 /* start a new check operation if there are < 2 failures */
3820                 if (s->failed == s->q_failed) {
3821                         /* The only possible failed device holds Q, so it
3822                          * makes sense to check P (If anything else were failed,
3823                          * we would have used P to recreate it).
3824                          */
3825                         sh->check_state = check_state_run;
3826                 }
3827                 if (!s->q_failed && s->failed < 2) {
3828                         /* Q is not failed, and we didn't use it to generate
3829                          * anything, so it makes sense to check it
3830                          */
3831                         if (sh->check_state == check_state_run)
3832                                 sh->check_state = check_state_run_pq;
3833                         else
3834                                 sh->check_state = check_state_run_q;
3835                 }
3836
3837                 /* discard potentially stale zero_sum_result */
3838                 sh->ops.zero_sum_result = 0;
3839
3840                 if (sh->check_state == check_state_run) {
3841                         /* async_xor_zero_sum destroys the contents of P */
3842                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3843                         s->uptodate--;
3844                 }
3845                 if (sh->check_state >= check_state_run &&
3846                     sh->check_state <= check_state_run_pq) {
3847                         /* async_syndrome_zero_sum preserves P and Q, so
3848                          * no need to mark them !uptodate here
3849                          */
3850                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3851                         break;
3852                 }
3853
3854                 /* we have 2-disk failure */
3855                 BUG_ON(s->failed != 2);
3856                 /* fall through */
3857         case check_state_compute_result:
3858                 sh->check_state = check_state_idle;
3859
3860                 /* check that a write has not made the stripe insync */
3861                 if (test_bit(STRIPE_INSYNC, &sh->state))
3862                         break;
3863
3864                 /* now write out any block on a failed drive,
3865                  * or P or Q if they were recomputed
3866                  */
3867                 dev = NULL;
3868                 if (s->failed == 2) {
3869                         dev = &sh->dev[s->failed_num[1]];
3870                         s->locked++;
3871                         set_bit(R5_LOCKED, &dev->flags);
3872                         set_bit(R5_Wantwrite, &dev->flags);
3873                 }
3874                 if (s->failed >= 1) {
3875                         dev = &sh->dev[s->failed_num[0]];
3876                         s->locked++;
3877                         set_bit(R5_LOCKED, &dev->flags);
3878                         set_bit(R5_Wantwrite, &dev->flags);
3879                 }
3880                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3881                         dev = &sh->dev[pd_idx];
3882                         s->locked++;
3883                         set_bit(R5_LOCKED, &dev->flags);
3884                         set_bit(R5_Wantwrite, &dev->flags);
3885                 }
3886                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3887                         dev = &sh->dev[qd_idx];
3888                         s->locked++;
3889                         set_bit(R5_LOCKED, &dev->flags);
3890                         set_bit(R5_Wantwrite, &dev->flags);
3891                 }
3892                 if (WARN_ONCE(dev && !test_bit(R5_UPTODATE, &dev->flags),
3893                               "%s: disk%td not up to date\n",
3894                               mdname(conf->mddev),
3895                               dev - (struct r5dev *) &sh->dev)) {
3896                         clear_bit(R5_LOCKED, &dev->flags);
3897                         clear_bit(R5_Wantwrite, &dev->flags);
3898                         s->locked--;
3899                 }
3900                 clear_bit(STRIPE_DEGRADED, &sh->state);
3901
3902                 set_bit(STRIPE_INSYNC, &sh->state);
3903                 break;
3904         case check_state_run:
3905         case check_state_run_q:
3906         case check_state_run_pq:
3907                 break; /* we will be called again upon completion */
3908         case check_state_check_result:
3909                 sh->check_state = check_state_idle;
3910
3911                 /* handle a successful check operation, if parity is correct
3912                  * we are done.  Otherwise update the mismatch count and repair
3913                  * parity if !MD_RECOVERY_CHECK
3914                  */
3915                 if (sh->ops.zero_sum_result == 0) {
3916                         /* both parities are correct */
3917                         if (!s->failed)
3918                                 set_bit(STRIPE_INSYNC, &sh->state);
3919                         else {
3920                                 /* in contrast to the raid5 case we can validate
3921                                  * parity, but still have a failure to write
3922                                  * back
3923                                  */
3924                                 sh->check_state = check_state_compute_result;
3925                                 /* Returning at this point means that we may go
3926                                  * off and bring p and/or q uptodate again so
3927                                  * we make sure to check zero_sum_result again
3928                                  * to verify if p or q need writeback
3929                                  */
3930                         }
3931                 } else {
3932                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3933                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3934                                 /* don't try to repair!! */
3935                                 set_bit(STRIPE_INSYNC, &sh->state);
3936                         else {
3937                                 int *target = &sh->ops.target;
3938
3939                                 sh->ops.target = -1;
3940                                 sh->ops.target2 = -1;
3941                                 sh->check_state = check_state_compute_run;
3942                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3943                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3944                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3945                                         set_bit(R5_Wantcompute,
3946                                                 &sh->dev[pd_idx].flags);
3947                                         *target = pd_idx;
3948                                         target = &sh->ops.target2;
3949                                         s->uptodate++;
3950                                 }
3951                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3952                                         set_bit(R5_Wantcompute,
3953                                                 &sh->dev[qd_idx].flags);
3954                                         *target = qd_idx;
3955                                         s->uptodate++;
3956                                 }
3957                         }
3958                 }
3959                 break;
3960         case check_state_compute_run:
3961                 break;
3962         default:
3963                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3964                        __func__, sh->check_state,
3965                        (unsigned long long) sh->sector);
3966                 BUG();
3967         }
3968 }
3969
3970 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3971 {
3972         int i;
3973
3974         /* We have read all the blocks in this stripe and now we need to
3975          * copy some of them into a target stripe for expand.
3976          */
3977         struct dma_async_tx_descriptor *tx = NULL;
3978         BUG_ON(sh->batch_head);
3979         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3980         for (i = 0; i < sh->disks; i++)
3981                 if (i != sh->pd_idx && i != sh->qd_idx) {
3982                         int dd_idx, j;
3983                         struct stripe_head *sh2;
3984                         struct async_submit_ctl submit;
3985
3986                         sector_t bn = raid5_compute_blocknr(sh, i, 1);
3987                         sector_t s = raid5_compute_sector(conf, bn, 0,
3988                                                           &dd_idx, NULL);
3989                         sh2 = raid5_get_active_stripe(conf, s, 0, 1, 1);
3990                         if (sh2 == NULL)
3991                                 /* so far only the early blocks of this stripe
3992                                  * have been requested.  When later blocks
3993                                  * get requested, we will try again
3994                                  */
3995                                 continue;
3996                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3997                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3998                                 /* must have already done this block */
3999                                 raid5_release_stripe(sh2);
4000                                 continue;
4001                         }
4002
4003                         /* place all the copies on one channel */
4004                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
4005                         tx = async_memcpy(sh2->dev[dd_idx].page,
4006                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
4007                                           &submit);
4008
4009                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
4010                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
4011                         for (j = 0; j < conf->raid_disks; j++)
4012                                 if (j != sh2->pd_idx &&
4013                                     j != sh2->qd_idx &&
4014                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
4015                                         break;
4016                         if (j == conf->raid_disks) {
4017                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
4018                                 set_bit(STRIPE_HANDLE, &sh2->state);
4019                         }
4020                         raid5_release_stripe(sh2);
4021
4022                 }
4023         /* done submitting copies, wait for them to complete */
4024         async_tx_quiesce(&tx);
4025 }
4026
4027 /*
4028  * handle_stripe - do things to a stripe.
4029  *
4030  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
4031  * state of various bits to see what needs to be done.
4032  * Possible results:
4033  *    return some read requests which now have data
4034  *    return some write requests which are safely on storage
4035  *    schedule a read on some buffers
4036  *    schedule a write of some buffers
4037  *    return confirmation of parity correctness
4038  *
4039  */
4040
4041 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
4042 {
4043         struct r5conf *conf = sh->raid_conf;
4044         int disks = sh->disks;
4045         struct r5dev *dev;
4046         int i;
4047         int do_recovery = 0;
4048
4049         memset(s, 0, sizeof(*s));
4050
4051         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state) && !sh->batch_head;
4052         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state) && !sh->batch_head;
4053         s->failed_num[0] = -1;
4054         s->failed_num[1] = -1;
4055         s->log_failed = r5l_log_disk_error(conf);
4056
4057         /* Now to look around and see what can be done */
4058         rcu_read_lock();
4059         for (i=disks; i--; ) {
4060                 struct md_rdev *rdev;
4061                 sector_t first_bad;
4062                 int bad_sectors;
4063                 int is_bad = 0;
4064
4065                 dev = &sh->dev[i];
4066
4067                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
4068                          i, dev->flags,
4069                          dev->toread, dev->towrite, dev->written);
4070                 /* maybe we can reply to a read
4071                  *
4072                  * new wantfill requests are only permitted while
4073                  * ops_complete_biofill is guaranteed to be inactive
4074                  */
4075                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
4076                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
4077                         set_bit(R5_Wantfill, &dev->flags);
4078
4079                 /* now count some things */
4080                 if (test_bit(R5_LOCKED, &dev->flags))
4081                         s->locked++;
4082                 if (test_bit(R5_UPTODATE, &dev->flags))
4083                         s->uptodate++;
4084                 if (test_bit(R5_Wantcompute, &dev->flags)) {
4085                         s->compute++;
4086                         BUG_ON(s->compute > 2);
4087                 }
4088
4089                 if (test_bit(R5_Wantfill, &dev->flags))
4090                         s->to_fill++;
4091                 else if (dev->toread)
4092                         s->to_read++;
4093                 if (dev->towrite) {
4094                         s->to_write++;
4095                         if (!test_bit(R5_OVERWRITE, &dev->flags))
4096                                 s->non_overwrite++;
4097                 }
4098                 if (dev->written)
4099                         s->written++;
4100                 /* Prefer to use the replacement for reads, but only
4101                  * if it is recovered enough and has no bad blocks.
4102                  */
4103                 rdev = rcu_dereference(conf->disks[i].replacement);
4104                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
4105                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
4106                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4107                                  &first_bad, &bad_sectors))
4108                         set_bit(R5_ReadRepl, &dev->flags);
4109                 else {
4110                         if (rdev && !test_bit(Faulty, &rdev->flags))
4111                                 set_bit(R5_NeedReplace, &dev->flags);
4112                         else
4113                                 clear_bit(R5_NeedReplace, &dev->flags);
4114                         rdev = rcu_dereference(conf->disks[i].rdev);
4115                         clear_bit(R5_ReadRepl, &dev->flags);
4116                 }
4117                 if (rdev && test_bit(Faulty, &rdev->flags))
4118                         rdev = NULL;
4119                 if (rdev) {
4120                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
4121                                              &first_bad, &bad_sectors);
4122                         if (s->blocked_rdev == NULL
4123                             && (test_bit(Blocked, &rdev->flags)
4124                                 || is_bad < 0)) {
4125                                 if (is_bad < 0)
4126                                         set_bit(BlockedBadBlocks,
4127                                                 &rdev->flags);
4128                                 s->blocked_rdev = rdev;
4129                                 atomic_inc(&rdev->nr_pending);
4130                         }
4131                 }
4132                 clear_bit(R5_Insync, &dev->flags);
4133                 if (!rdev)
4134                         /* Not in-sync */;
4135                 else if (is_bad) {
4136                         /* also not in-sync */
4137                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
4138                             test_bit(R5_UPTODATE, &dev->flags)) {
4139                                 /* treat as in-sync, but with a read error
4140                                  * which we can now try to correct
4141                                  */
4142                                 set_bit(R5_Insync, &dev->flags);
4143                                 set_bit(R5_ReadError, &dev->flags);
4144                         }
4145                 } else if (test_bit(In_sync, &rdev->flags))
4146                         set_bit(R5_Insync, &dev->flags);
4147                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
4148                         /* in sync if before recovery_offset */
4149                         set_bit(R5_Insync, &dev->flags);
4150                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
4151                          test_bit(R5_Expanded, &dev->flags))
4152                         /* If we've reshaped into here, we assume it is Insync.
4153                          * We will shortly update recovery_offset to make
4154                          * it official.
4155                          */
4156                         set_bit(R5_Insync, &dev->flags);
4157
4158                 if (test_bit(R5_WriteError, &dev->flags)) {
4159                         /* This flag does not apply to '.replacement'
4160                          * only to .rdev, so make sure to check that*/
4161                         struct md_rdev *rdev2 = rcu_dereference(
4162                                 conf->disks[i].rdev);
4163                         if (rdev2 == rdev)
4164                                 clear_bit(R5_Insync, &dev->flags);
4165                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4166                                 s->handle_bad_blocks = 1;
4167                                 atomic_inc(&rdev2->nr_pending);
4168                         } else
4169                                 clear_bit(R5_WriteError, &dev->flags);
4170                 }
4171                 if (test_bit(R5_MadeGood, &dev->flags)) {
4172                         /* This flag does not apply to '.replacement'
4173                          * only to .rdev, so make sure to check that*/
4174                         struct md_rdev *rdev2 = rcu_dereference(
4175                                 conf->disks[i].rdev);
4176                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4177                                 s->handle_bad_blocks = 1;
4178                                 atomic_inc(&rdev2->nr_pending);
4179                         } else
4180                                 clear_bit(R5_MadeGood, &dev->flags);
4181                 }
4182                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
4183                         struct md_rdev *rdev2 = rcu_dereference(
4184                                 conf->disks[i].replacement);
4185                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
4186                                 s->handle_bad_blocks = 1;
4187                                 atomic_inc(&rdev2->nr_pending);
4188                         } else
4189                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
4190                 }
4191                 if (!test_bit(R5_Insync, &dev->flags)) {
4192                         /* The ReadError flag will just be confusing now */
4193                         clear_bit(R5_ReadError, &dev->flags);
4194                         clear_bit(R5_ReWrite, &dev->flags);
4195                 }
4196                 if (test_bit(R5_ReadError, &dev->flags))
4197                         clear_bit(R5_Insync, &dev->flags);
4198                 if (!test_bit(R5_Insync, &dev->flags)) {
4199                         if (s->failed < 2)
4200                                 s->failed_num[s->failed] = i;
4201                         s->failed++;
4202                         if (rdev && !test_bit(Faulty, &rdev->flags))
4203                                 do_recovery = 1;
4204                         else if (!rdev) {
4205                                 rdev = rcu_dereference(
4206                                     conf->disks[i].replacement);
4207                                 if (rdev && !test_bit(Faulty, &rdev->flags))
4208                                         do_recovery = 1;
4209                         }
4210                 }
4211         }
4212         if (test_bit(STRIPE_SYNCING, &sh->state)) {
4213                 /* If there is a failed device being replaced,
4214                  *     we must be recovering.
4215                  * else if we are after recovery_cp, we must be syncing
4216                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
4217                  * else we can only be replacing
4218                  * sync and recovery both need to read all devices, and so
4219                  * use the same flag.
4220                  */
4221                 if (do_recovery ||
4222                     sh->sector >= conf->mddev->recovery_cp ||
4223                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
4224                         s->syncing = 1;
4225                 else
4226                         s->replacing = 1;
4227         }
4228         rcu_read_unlock();
4229 }
4230
4231 static int clear_batch_ready(struct stripe_head *sh)
4232 {
4233         /* Return '1' if this is a member of batch, or
4234          * '0' if it is a lone stripe or a head which can now be
4235          * handled.
4236          */
4237         struct stripe_head *tmp;
4238         if (!test_and_clear_bit(STRIPE_BATCH_READY, &sh->state))
4239                 return (sh->batch_head && sh->batch_head != sh);
4240         spin_lock(&sh->stripe_lock);
4241         if (!sh->batch_head) {
4242                 spin_unlock(&sh->stripe_lock);
4243                 return 0;
4244         }
4245
4246         /*
4247          * this stripe could be added to a batch list before we check
4248          * BATCH_READY, skips it
4249          */
4250         if (sh->batch_head != sh) {
4251                 spin_unlock(&sh->stripe_lock);
4252                 return 1;
4253         }
4254         spin_lock(&sh->batch_lock);
4255         list_for_each_entry(tmp, &sh->batch_list, batch_list)
4256                 clear_bit(STRIPE_BATCH_READY, &tmp->state);
4257         spin_unlock(&sh->batch_lock);
4258         spin_unlock(&sh->stripe_lock);
4259
4260         /*
4261          * BATCH_READY is cleared, no new stripes can be added.
4262          * batch_list can be accessed without lock
4263          */
4264         return 0;
4265 }
4266
4267 static void break_stripe_batch_list(struct stripe_head *head_sh,
4268                                     unsigned long handle_flags)
4269 {
4270         struct stripe_head *sh, *next;
4271         int i;
4272         int do_wakeup = 0;
4273
4274         list_for_each_entry_safe(sh, next, &head_sh->batch_list, batch_list) {
4275
4276                 list_del_init(&sh->batch_list);
4277
4278                 WARN_ON_ONCE(sh->state & ((1 << STRIPE_ACTIVE) |
4279                                           (1 << STRIPE_SYNCING) |
4280                                           (1 << STRIPE_REPLACED) |
4281                                           (1 << STRIPE_DELAYED) |
4282                                           (1 << STRIPE_BIT_DELAY) |
4283                                           (1 << STRIPE_FULL_WRITE) |
4284                                           (1 << STRIPE_BIOFILL_RUN) |
4285                                           (1 << STRIPE_COMPUTE_RUN)  |
4286                                           (1 << STRIPE_OPS_REQ_PENDING) |
4287                                           (1 << STRIPE_DISCARD) |
4288                                           (1 << STRIPE_BATCH_READY) |
4289                                           (1 << STRIPE_BATCH_ERR) |
4290                                           (1 << STRIPE_BITMAP_PENDING)));
4291                 WARN_ON_ONCE(head_sh->state & ((1 << STRIPE_DISCARD) |
4292                                               (1 << STRIPE_REPLACED)));
4293
4294                 set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
4295                                             (1 << STRIPE_PREREAD_ACTIVE) |
4296                                             (1 << STRIPE_DEGRADED) |
4297                                             (1 << STRIPE_ON_UNPLUG_LIST)),
4298                               head_sh->state & (1 << STRIPE_INSYNC));
4299
4300                 sh->check_state = head_sh->check_state;
4301                 sh->reconstruct_state = head_sh->reconstruct_state;
4302                 for (i = 0; i < sh->disks; i++) {
4303                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
4304                                 do_wakeup = 1;
4305                         sh->dev[i].flags = head_sh->dev[i].flags &
4306                                 (~((1 << R5_WriteError) | (1 << R5_Overlap)));
4307                 }
4308                 spin_lock_irq(&sh->stripe_lock);
4309                 sh->batch_head = NULL;
4310                 spin_unlock_irq(&sh->stripe_lock);
4311                 if (handle_flags == 0 ||
4312                     sh->state & handle_flags)
4313                         set_bit(STRIPE_HANDLE, &sh->state);
4314                 raid5_release_stripe(sh);
4315         }
4316         spin_lock_irq(&head_sh->stripe_lock);
4317         head_sh->batch_head = NULL;
4318         spin_unlock_irq(&head_sh->stripe_lock);
4319         for (i = 0; i < head_sh->disks; i++)
4320                 if (test_and_clear_bit(R5_Overlap, &head_sh->dev[i].flags))
4321                         do_wakeup = 1;
4322         if (head_sh->state & handle_flags)
4323                 set_bit(STRIPE_HANDLE, &head_sh->state);
4324
4325         if (do_wakeup)
4326                 wake_up(&head_sh->raid_conf->wait_for_overlap);
4327 }
4328
4329 static void handle_stripe(struct stripe_head *sh)
4330 {
4331         struct stripe_head_state s;
4332         struct r5conf *conf = sh->raid_conf;
4333         int i;
4334         int prexor;
4335         int disks = sh->disks;
4336         struct r5dev *pdev, *qdev;
4337
4338         clear_bit(STRIPE_HANDLE, &sh->state);
4339         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
4340                 /* already being handled, ensure it gets handled
4341                  * again when current action finishes */
4342                 set_bit(STRIPE_HANDLE, &sh->state);
4343                 return;
4344         }
4345
4346         if (clear_batch_ready(sh) ) {
4347                 clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4348                 return;
4349         }
4350
4351         if (test_and_clear_bit(STRIPE_BATCH_ERR, &sh->state))
4352                 break_stripe_batch_list(sh, 0);
4353
4354         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
4355                 spin_lock(&sh->stripe_lock);
4356                 /* Cannot process 'sync' concurrently with 'discard' */
4357                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
4358                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
4359                         set_bit(STRIPE_SYNCING, &sh->state);
4360                         clear_bit(STRIPE_INSYNC, &sh->state);
4361                         clear_bit(STRIPE_REPLACED, &sh->state);
4362                 }
4363                 spin_unlock(&sh->stripe_lock);
4364         }
4365         clear_bit(STRIPE_DELAYED, &sh->state);
4366
4367         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
4368                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
4369                (unsigned long long)sh->sector, sh->state,
4370                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
4371                sh->check_state, sh->reconstruct_state);
4372
4373         analyse_stripe(sh, &s);
4374
4375         if (test_bit(STRIPE_LOG_TRAPPED, &sh->state))
4376                 goto finish;
4377
4378         if (s.handle_bad_blocks) {
4379                 set_bit(STRIPE_HANDLE, &sh->state);
4380                 goto finish;
4381         }
4382
4383         if (unlikely(s.blocked_rdev)) {
4384                 if (s.syncing || s.expanding || s.expanded ||
4385                     s.replacing || s.to_write || s.written) {
4386                         set_bit(STRIPE_HANDLE, &sh->state);
4387                         goto finish;
4388                 }
4389                 /* There is nothing for the blocked_rdev to block */
4390                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
4391                 s.blocked_rdev = NULL;
4392         }
4393
4394         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
4395                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
4396                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
4397         }
4398
4399         pr_debug("locked=%d uptodate=%d to_read=%d"
4400                " to_write=%d failed=%d failed_num=%d,%d\n",
4401                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
4402                s.failed_num[0], s.failed_num[1]);
4403         /* check if the array has lost more than max_degraded devices and,
4404          * if so, some requests might need to be failed.
4405          */
4406         if (s.failed > conf->max_degraded || s.log_failed) {
4407                 sh->check_state = 0;
4408                 sh->reconstruct_state = 0;
4409                 break_stripe_batch_list(sh, 0);
4410                 if (s.to_read+s.to_write+s.written)
4411                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
4412                 if (s.syncing + s.replacing)
4413                         handle_failed_sync(conf, sh, &s);
4414         }
4415
4416         /* Now we check to see if any write operations have recently
4417          * completed
4418          */
4419         prexor = 0;
4420         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
4421                 prexor = 1;
4422         if (sh->reconstruct_state == reconstruct_state_drain_result ||
4423             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
4424                 sh->reconstruct_state = reconstruct_state_idle;
4425
4426                 /* All the 'written' buffers and the parity block are ready to
4427                  * be written back to disk
4428                  */
4429                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
4430                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
4431                 BUG_ON(sh->qd_idx >= 0 &&
4432                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
4433                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
4434                 for (i = disks; i--; ) {
4435                         struct r5dev *dev = &sh->dev[i];
4436                         if (test_bit(R5_LOCKED, &dev->flags) &&
4437                                 (i == sh->pd_idx || i == sh->qd_idx ||
4438                                  dev->written)) {
4439                                 pr_debug("Writing block %d\n", i);
4440                                 set_bit(R5_Wantwrite, &dev->flags);
4441                                 if (prexor)
4442                                         continue;
4443                                 if (s.failed > 1)
4444                                         continue;
4445                                 if (!test_bit(R5_Insync, &dev->flags) ||
4446                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
4447                                      s.failed == 0))
4448                                         set_bit(STRIPE_INSYNC, &sh->state);
4449                         }
4450                 }
4451                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4452                         s.dec_preread_active = 1;
4453         }
4454
4455         /*
4456          * might be able to return some write requests if the parity blocks
4457          * are safe, or on a failed drive
4458          */
4459         pdev = &sh->dev[sh->pd_idx];
4460         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
4461                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
4462         qdev = &sh->dev[sh->qd_idx];
4463         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
4464                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
4465                 || conf->level < 6;
4466
4467         if (s.written &&
4468             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
4469                              && !test_bit(R5_LOCKED, &pdev->flags)
4470                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
4471                                  test_bit(R5_Discard, &pdev->flags))))) &&
4472             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
4473                              && !test_bit(R5_LOCKED, &qdev->flags)
4474                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
4475                                  test_bit(R5_Discard, &qdev->flags))))))
4476                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
4477
4478         /* Now we might consider reading some blocks, either to check/generate
4479          * parity, or to satisfy requests
4480          * or to load a block that is being partially written.
4481          */
4482         if (s.to_read || s.non_overwrite
4483             || (s.to_write && s.failed)
4484             || (s.syncing && (s.uptodate + s.compute < disks))
4485             || s.replacing
4486             || s.expanding)
4487                 handle_stripe_fill(sh, &s, disks);
4488
4489         /* Now to consider new write requests and what else, if anything
4490          * should be read.  We do not handle new writes when:
4491          * 1/ A 'write' operation (copy+xor) is already in flight.
4492          * 2/ A 'check' operation is in flight, as it may clobber the parity
4493          *    block.
4494          */
4495         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
4496                 handle_stripe_dirtying(conf, sh, &s, disks);
4497
4498         /* maybe we need to check and possibly fix the parity for this stripe
4499          * Any reads will already have been scheduled, so we just see if enough
4500          * data is available.  The parity check is held off while parity
4501          * dependent operations are in flight.
4502          */
4503         if (sh->check_state ||
4504             (s.syncing && s.locked == 0 &&
4505              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4506              !test_bit(STRIPE_INSYNC, &sh->state))) {
4507                 if (conf->level == 6)
4508                         handle_parity_checks6(conf, sh, &s, disks);
4509                 else
4510                         handle_parity_checks5(conf, sh, &s, disks);
4511         }
4512
4513         if ((s.replacing || s.syncing) && s.locked == 0
4514             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
4515             && !test_bit(STRIPE_REPLACED, &sh->state)) {
4516                 /* Write out to replacement devices where possible */
4517                 for (i = 0; i < conf->raid_disks; i++)
4518                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
4519                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
4520                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
4521                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
4522                                 s.locked++;
4523                         }
4524                 if (s.replacing)
4525                         set_bit(STRIPE_INSYNC, &sh->state);
4526                 set_bit(STRIPE_REPLACED, &sh->state);
4527         }
4528         if ((s.syncing || s.replacing) && s.locked == 0 &&
4529             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
4530             test_bit(STRIPE_INSYNC, &sh->state)) {
4531                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4532                 clear_bit(STRIPE_SYNCING, &sh->state);
4533                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
4534                         wake_up(&conf->wait_for_overlap);
4535         }
4536
4537         /* If the failed drives are just a ReadError, then we might need
4538          * to progress the repair/check process
4539          */
4540         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
4541                 for (i = 0; i < s.failed; i++) {
4542                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
4543                         if (test_bit(R5_ReadError, &dev->flags)
4544                             && !test_bit(R5_LOCKED, &dev->flags)
4545                             && test_bit(R5_UPTODATE, &dev->flags)
4546                                 ) {
4547                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
4548                                         set_bit(R5_Wantwrite, &dev->flags);
4549                                         set_bit(R5_ReWrite, &dev->flags);
4550                                         set_bit(R5_LOCKED, &dev->flags);
4551                                         s.locked++;
4552                                 } else {
4553                                         /* let's read it back */
4554                                         set_bit(R5_Wantread, &dev->flags);
4555                                         set_bit(R5_LOCKED, &dev->flags);
4556                                         s.locked++;
4557                                 }
4558                         }
4559                 }
4560
4561         /* Finish reconstruct operations initiated by the expansion process */
4562         if (sh->reconstruct_state == reconstruct_state_result) {
4563                 struct stripe_head *sh_src
4564                         = raid5_get_active_stripe(conf, sh->sector, 1, 1, 1);
4565                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
4566                         /* sh cannot be written until sh_src has been read.
4567                          * so arrange for sh to be delayed a little
4568                          */
4569                         set_bit(STRIPE_DELAYED, &sh->state);
4570                         set_bit(STRIPE_HANDLE, &sh->state);
4571                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
4572                                               &sh_src->state))
4573                                 atomic_inc(&conf->preread_active_stripes);
4574                         raid5_release_stripe(sh_src);
4575                         goto finish;
4576                 }
4577                 if (sh_src)
4578                         raid5_release_stripe(sh_src);
4579
4580                 sh->reconstruct_state = reconstruct_state_idle;
4581                 clear_bit(STRIPE_EXPANDING, &sh->state);
4582                 for (i = conf->raid_disks; i--; ) {
4583                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
4584                         set_bit(R5_LOCKED, &sh->dev[i].flags);
4585                         s.locked++;
4586                 }
4587         }
4588
4589         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
4590             !sh->reconstruct_state) {
4591                 /* Need to write out all blocks after computing parity */
4592                 sh->disks = conf->raid_disks;
4593                 stripe_set_idx(sh->sector, conf, 0, sh);
4594                 schedule_reconstruction(sh, &s, 1, 1);
4595         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
4596                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
4597                 atomic_dec(&conf->reshape_stripes);
4598                 wake_up(&conf->wait_for_overlap);
4599                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
4600         }
4601
4602         if (s.expanding && s.locked == 0 &&
4603             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
4604                 handle_stripe_expansion(conf, sh);
4605
4606 finish:
4607         /* wait for this device to become unblocked */
4608         if (unlikely(s.blocked_rdev)) {
4609                 if (conf->mddev->external)
4610                         md_wait_for_blocked_rdev(s.blocked_rdev,
4611                                                  conf->mddev);
4612                 else
4613                         /* Internal metadata will immediately
4614                          * be written by raid5d, so we don't
4615                          * need to wait here.
4616                          */
4617                         rdev_dec_pending(s.blocked_rdev,
4618                                          conf->mddev);
4619         }
4620
4621         if (s.handle_bad_blocks)
4622                 for (i = disks; i--; ) {
4623                         struct md_rdev *rdev;
4624                         struct r5dev *dev = &sh->dev[i];
4625                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4626                                 /* We own a safe reference to the rdev */
4627                                 rdev = conf->disks[i].rdev;
4628                                 if (!rdev_set_badblocks(rdev, sh->sector,
4629                                                         STRIPE_SECTORS, 0))
4630                                         md_error(conf->mddev, rdev);
4631                                 rdev_dec_pending(rdev, conf->mddev);
4632                         }
4633                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4634                                 rdev = conf->disks[i].rdev;
4635                                 rdev_clear_badblocks(rdev, sh->sector,
4636                                                      STRIPE_SECTORS, 0);
4637                                 rdev_dec_pending(rdev, conf->mddev);
4638                         }
4639                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4640                                 rdev = conf->disks[i].replacement;
4641                                 if (!rdev)
4642                                         /* rdev have been moved down */
4643                                         rdev = conf->disks[i].rdev;
4644                                 rdev_clear_badblocks(rdev, sh->sector,
4645                                                      STRIPE_SECTORS, 0);
4646                                 rdev_dec_pending(rdev, conf->mddev);
4647                         }
4648                 }
4649
4650         if (s.ops_request)
4651                 raid_run_ops(sh, s.ops_request);
4652
4653         ops_run_io(sh, &s);
4654
4655         if (s.dec_preread_active) {
4656                 /* We delay this until after ops_run_io so that if make_request
4657                  * is waiting on a flush, it won't continue until the writes
4658                  * have actually been submitted.
4659                  */
4660                 atomic_dec(&conf->preread_active_stripes);
4661                 if (atomic_read(&conf->preread_active_stripes) <
4662                     IO_THRESHOLD)
4663                         md_wakeup_thread(conf->mddev->thread);
4664         }
4665
4666         if (!bio_list_empty(&s.return_bi)) {
4667                 if (test_bit(MD_CHANGE_PENDING, &conf->mddev->flags)) {
4668                         spin_lock_irq(&conf->device_lock);
4669                         bio_list_merge(&conf->return_bi, &s.return_bi);
4670                         spin_unlock_irq(&conf->device_lock);
4671                         md_wakeup_thread(conf->mddev->thread);
4672                 } else
4673                         return_io(&s.return_bi);
4674         }
4675
4676         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4677 }
4678
4679 static void raid5_activate_delayed(struct r5conf *conf)
4680 {
4681         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4682                 while (!list_empty(&conf->delayed_list)) {
4683                         struct list_head *l = conf->delayed_list.next;
4684                         struct stripe_head *sh;
4685                         sh = list_entry(l, struct stripe_head, lru);
4686                         list_del_init(l);
4687                         clear_bit(STRIPE_DELAYED, &sh->state);
4688                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4689                                 atomic_inc(&conf->preread_active_stripes);
4690                         list_add_tail(&sh->lru, &conf->hold_list);
4691                         raid5_wakeup_stripe_thread(sh);
4692                 }
4693         }
4694 }
4695
4696 static void activate_bit_delay(struct r5conf *conf,
4697         struct list_head *temp_inactive_list)
4698 {
4699         /* device_lock is held */
4700         struct list_head head;
4701         list_add(&head, &conf->bitmap_list);
4702         list_del_init(&conf->bitmap_list);
4703         while (!list_empty(&head)) {
4704                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4705                 int hash;
4706                 list_del_init(&sh->lru);
4707                 atomic_inc(&sh->count);
4708                 hash = sh->hash_lock_index;
4709                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
4710         }
4711 }
4712
4713 static int raid5_congested(struct mddev *mddev, int bits)
4714 {
4715         struct r5conf *conf = mddev->private;
4716
4717         /* No difference between reads and writes.  Just check
4718          * how busy the stripe_cache is
4719          */
4720
4721         if (test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state))
4722                 return 1;
4723         if (conf->quiesce)
4724                 return 1;
4725         if (atomic_read(&conf->empty_inactive_list_nr))
4726                 return 1;
4727
4728         return 0;
4729 }
4730
4731 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4732 {
4733         struct r5conf *conf = mddev->private;
4734         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4735         unsigned int chunk_sectors;
4736         unsigned int bio_sectors = bio_sectors(bio);
4737
4738         chunk_sectors = min(conf->chunk_sectors, conf->prev_chunk_sectors);
4739         return  chunk_sectors >=
4740                 ((sector & (chunk_sectors - 1)) + bio_sectors);
4741 }
4742
4743 /*
4744  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4745  *  later sampled by raid5d.
4746  */
4747 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4748 {
4749         unsigned long flags;
4750
4751         spin_lock_irqsave(&conf->device_lock, flags);
4752
4753         bi->bi_next = conf->retry_read_aligned_list;
4754         conf->retry_read_aligned_list = bi;
4755
4756         spin_unlock_irqrestore(&conf->device_lock, flags);
4757         md_wakeup_thread(conf->mddev->thread);
4758 }
4759
4760 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4761 {
4762         struct bio *bi;
4763
4764         bi = conf->retry_read_aligned;
4765         if (bi) {
4766                 conf->retry_read_aligned = NULL;
4767                 return bi;
4768         }
4769         bi = conf->retry_read_aligned_list;
4770         if(bi) {
4771                 conf->retry_read_aligned_list = bi->bi_next;
4772                 bi->bi_next = NULL;
4773                 /*
4774                  * this sets the active strip count to 1 and the processed
4775                  * strip count to zero (upper 8 bits)
4776                  */
4777                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4778         }
4779
4780         return bi;
4781 }
4782
4783 /*
4784  *  The "raid5_align_endio" should check if the read succeeded and if it
4785  *  did, call bio_endio on the original bio (having bio_put the new bio
4786  *  first).
4787  *  If the read failed..
4788  */
4789 static void raid5_align_endio(struct bio *bi)
4790 {
4791         struct bio* raid_bi  = bi->bi_private;
4792         struct mddev *mddev;
4793         struct r5conf *conf;
4794         struct md_rdev *rdev;
4795         int error = bi->bi_error;
4796
4797         bio_put(bi);
4798
4799         rdev = (void*)raid_bi->bi_next;
4800         raid_bi->bi_next = NULL;
4801         mddev = rdev->mddev;
4802         conf = mddev->private;
4803
4804         rdev_dec_pending(rdev, conf->mddev);
4805
4806         if (!error) {
4807                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4808                                          raid_bi, 0);
4809                 bio_endio(raid_bi);
4810                 if (atomic_dec_and_test(&conf->active_aligned_reads))
4811                         wake_up(&conf->wait_for_quiescent);
4812                 return;
4813         }
4814
4815         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4816
4817         add_bio_to_retry(raid_bi, conf);
4818 }
4819
4820 static int raid5_read_one_chunk(struct mddev *mddev, struct bio *raid_bio)
4821 {
4822         struct r5conf *conf = mddev->private;
4823         int dd_idx;
4824         struct bio* align_bi;
4825         struct md_rdev *rdev;
4826         sector_t end_sector;
4827
4828         if (!in_chunk_boundary(mddev, raid_bio)) {
4829                 pr_debug("%s: non aligned\n", __func__);
4830                 return 0;
4831         }
4832         /*
4833          * use bio_clone_mddev to make a copy of the bio
4834          */
4835         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4836         if (!align_bi)
4837                 return 0;
4838         /*
4839          *   set bi_end_io to a new function, and set bi_private to the
4840          *     original bio.
4841          */
4842         align_bi->bi_end_io  = raid5_align_endio;
4843         align_bi->bi_private = raid_bio;
4844         /*
4845          *      compute position
4846          */
4847         align_bi->bi_iter.bi_sector =
4848                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4849                                      0, &dd_idx, NULL);
4850
4851         end_sector = bio_end_sector(align_bi);
4852         rcu_read_lock();
4853         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4854         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4855             rdev->recovery_offset < end_sector) {
4856                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4857                 if (rdev &&
4858                     (test_bit(Faulty, &rdev->flags) ||
4859                     !(test_bit(In_sync, &rdev->flags) ||
4860                       rdev->recovery_offset >= end_sector)))
4861                         rdev = NULL;
4862         }
4863         if (rdev) {
4864                 sector_t first_bad;
4865                 int bad_sectors;
4866
4867                 atomic_inc(&rdev->nr_pending);
4868                 rcu_read_unlock();
4869                 raid_bio->bi_next = (void*)rdev;
4870                 align_bi->bi_bdev =  rdev->bdev;
4871                 bio_clear_flag(align_bi, BIO_SEG_VALID);
4872
4873                 if (is_badblock(rdev, align_bi->bi_iter.bi_sector,
4874                                 bio_sectors(align_bi),
4875                                 &first_bad, &bad_sectors)) {
4876                         bio_put(align_bi);
4877                         rdev_dec_pending(rdev, mddev);
4878                         return 0;
4879                 }
4880
4881                 /* No reshape active, so we can trust rdev->data_offset */
4882                 align_bi->bi_iter.bi_sector += rdev->data_offset;
4883
4884                 spin_lock_irq(&conf->device_lock);
4885                 wait_event_lock_irq(conf->wait_for_quiescent,
4886                                     conf->quiesce == 0,
4887                                     conf->device_lock);
4888                 atomic_inc(&conf->active_aligned_reads);
4889                 spin_unlock_irq(&conf->device_lock);
4890
4891                 if (mddev->gendisk)
4892                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4893                                               align_bi, disk_devt(mddev->gendisk),
4894                                               raid_bio->bi_iter.bi_sector);
4895                 generic_make_request(align_bi);
4896                 return 1;
4897         } else {
4898                 rcu_read_unlock();
4899                 bio_put(align_bi);
4900                 return 0;
4901         }
4902 }
4903
4904 static struct bio *chunk_aligned_read(struct mddev *mddev, struct bio *raid_bio)
4905 {
4906         struct bio *split;
4907
4908         do {
4909                 sector_t sector = raid_bio->bi_iter.bi_sector;
4910                 unsigned chunk_sects = mddev->chunk_sectors;
4911                 unsigned sectors = chunk_sects - (sector & (chunk_sects-1));
4912
4913                 if (sectors < bio_sectors(raid_bio)) {
4914                         split = bio_split(raid_bio, sectors, GFP_NOIO, fs_bio_set);
4915                         bio_chain(split, raid_bio);
4916                 } else
4917                         split = raid_bio;
4918
4919                 if (!raid5_read_one_chunk(mddev, split)) {
4920                         if (split != raid_bio)
4921                                 generic_make_request(raid_bio);
4922                         return split;
4923                 }
4924         } while (split != raid_bio);
4925
4926         return NULL;
4927 }
4928
4929 /* __get_priority_stripe - get the next stripe to process
4930  *
4931  * Full stripe writes are allowed to pass preread active stripes up until
4932  * the bypass_threshold is exceeded.  In general the bypass_count
4933  * increments when the handle_list is handled before the hold_list; however, it
4934  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4935  * stripe with in flight i/o.  The bypass_count will be reset when the
4936  * head of the hold_list has changed, i.e. the head was promoted to the
4937  * handle_list.
4938  */
4939 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
4940 {
4941         struct stripe_head *sh = NULL, *tmp;
4942         struct list_head *handle_list = NULL;
4943         struct r5worker_group *wg = NULL;
4944
4945         if (conf->worker_cnt_per_group == 0) {
4946                 handle_list = &conf->handle_list;
4947         } else if (group != ANY_GROUP) {
4948                 handle_list = &conf->worker_groups[group].handle_list;
4949                 wg = &conf->worker_groups[group];
4950         } else {
4951                 int i;
4952                 for (i = 0; i < conf->group_cnt; i++) {
4953                         handle_list = &conf->worker_groups[i].handle_list;
4954                         wg = &conf->worker_groups[i];
4955                         if (!list_empty(handle_list))
4956                                 break;
4957                 }
4958         }
4959
4960         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4961                   __func__,
4962                   list_empty(handle_list) ? "empty" : "busy",
4963                   list_empty(&conf->hold_list) ? "empty" : "busy",
4964                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4965
4966         if (!list_empty(handle_list)) {
4967                 sh = list_entry(handle_list->next, typeof(*sh), lru);
4968
4969                 if (list_empty(&conf->hold_list))
4970                         conf->bypass_count = 0;
4971                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4972                         if (conf->hold_list.next == conf->last_hold)
4973                                 conf->bypass_count++;
4974                         else {
4975                                 conf->last_hold = conf->hold_list.next;
4976                                 conf->bypass_count -= conf->bypass_threshold;
4977                                 if (conf->bypass_count < 0)
4978                                         conf->bypass_count = 0;
4979                         }
4980                 }
4981         } else if (!list_empty(&conf->hold_list) &&
4982                    ((conf->bypass_threshold &&
4983                      conf->bypass_count > conf->bypass_threshold) ||
4984                     atomic_read(&conf->pending_full_writes) == 0)) {
4985
4986                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
4987                         if (conf->worker_cnt_per_group == 0 ||
4988                             group == ANY_GROUP ||
4989                             !cpu_online(tmp->cpu) ||
4990                             cpu_to_group(tmp->cpu) == group) {
4991                                 sh = tmp;
4992                                 break;
4993                         }
4994                 }
4995
4996                 if (sh) {
4997                         conf->bypass_count -= conf->bypass_threshold;
4998                         if (conf->bypass_count < 0)
4999                                 conf->bypass_count = 0;
5000                 }
5001                 wg = NULL;
5002         }
5003
5004         if (!sh)
5005                 return NULL;
5006
5007         if (wg) {
5008                 wg->stripes_cnt--;
5009                 sh->group = NULL;
5010         }
5011         list_del_init(&sh->lru);
5012         BUG_ON(atomic_inc_return(&sh->count) != 1);
5013         return sh;
5014 }
5015
5016 struct raid5_plug_cb {
5017         struct blk_plug_cb      cb;
5018         struct list_head        list;
5019         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
5020 };
5021
5022 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
5023 {
5024         struct raid5_plug_cb *cb = container_of(
5025                 blk_cb, struct raid5_plug_cb, cb);
5026         struct stripe_head *sh;
5027         struct mddev *mddev = cb->cb.data;
5028         struct r5conf *conf = mddev->private;
5029         int cnt = 0;
5030         int hash;
5031
5032         if (cb->list.next && !list_empty(&cb->list)) {
5033                 spin_lock_irq(&conf->device_lock);
5034                 while (!list_empty(&cb->list)) {
5035                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
5036                         list_del_init(&sh->lru);
5037                         /*
5038                          * avoid race release_stripe_plug() sees
5039                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
5040                          * is still in our list
5041                          */
5042                         smp_mb__before_atomic();
5043                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
5044                         /*
5045                          * STRIPE_ON_RELEASE_LIST could be set here. In that
5046                          * case, the count is always > 1 here
5047                          */
5048                         hash = sh->hash_lock_index;
5049                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
5050                         cnt++;
5051                 }
5052                 spin_unlock_irq(&conf->device_lock);
5053         }
5054         release_inactive_stripe_list(conf, cb->temp_inactive_list,
5055                                      NR_STRIPE_HASH_LOCKS);
5056         if (mddev->queue)
5057                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
5058         kfree(cb);
5059 }
5060
5061 static void release_stripe_plug(struct mddev *mddev,
5062                                 struct stripe_head *sh)
5063 {
5064         struct blk_plug_cb *blk_cb = blk_check_plugged(
5065                 raid5_unplug, mddev,
5066                 sizeof(struct raid5_plug_cb));
5067         struct raid5_plug_cb *cb;
5068
5069         if (!blk_cb) {
5070                 raid5_release_stripe(sh);
5071                 return;
5072         }
5073
5074         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
5075
5076         if (cb->list.next == NULL) {
5077                 int i;
5078                 INIT_LIST_HEAD(&cb->list);
5079                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5080                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
5081         }
5082
5083         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
5084                 list_add_tail(&sh->lru, &cb->list);
5085         else
5086                 raid5_release_stripe(sh);
5087 }
5088
5089 static void make_discard_request(struct mddev *mddev, struct bio *bi)
5090 {
5091         struct r5conf *conf = mddev->private;
5092         sector_t logical_sector, last_sector;
5093         struct stripe_head *sh;
5094         int remaining;
5095         int stripe_sectors;
5096
5097         if (mddev->reshape_position != MaxSector)
5098                 /* Skip discard while reshape is happening */
5099                 return;
5100
5101         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5102         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
5103
5104         bi->bi_next = NULL;
5105         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
5106
5107         stripe_sectors = conf->chunk_sectors *
5108                 (conf->raid_disks - conf->max_degraded);
5109         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
5110                                                stripe_sectors);
5111         sector_div(last_sector, stripe_sectors);
5112
5113         logical_sector *= conf->chunk_sectors;
5114         last_sector *= conf->chunk_sectors;
5115
5116         for (; logical_sector < last_sector;
5117              logical_sector += STRIPE_SECTORS) {
5118                 DEFINE_WAIT(w);
5119                 int d;
5120         again:
5121                 sh = raid5_get_active_stripe(conf, logical_sector, 0, 0, 0);
5122                 prepare_to_wait(&conf->wait_for_overlap, &w,
5123                                 TASK_UNINTERRUPTIBLE);
5124                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5125                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
5126                         raid5_release_stripe(sh);
5127                         schedule();
5128                         goto again;
5129                 }
5130                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
5131                 spin_lock_irq(&sh->stripe_lock);
5132                 for (d = 0; d < conf->raid_disks; d++) {
5133                         if (d == sh->pd_idx || d == sh->qd_idx)
5134                                 continue;
5135                         if (sh->dev[d].towrite || sh->dev[d].toread) {
5136                                 set_bit(R5_Overlap, &sh->dev[d].flags);
5137                                 spin_unlock_irq(&sh->stripe_lock);
5138                                 raid5_release_stripe(sh);
5139                                 schedule();
5140                                 goto again;
5141                         }
5142                 }
5143                 set_bit(STRIPE_DISCARD, &sh->state);
5144                 finish_wait(&conf->wait_for_overlap, &w);
5145                 sh->overwrite_disks = 0;
5146                 for (d = 0; d < conf->raid_disks; d++) {
5147                         if (d == sh->pd_idx || d == sh->qd_idx)
5148                                 continue;
5149                         sh->dev[d].towrite = bi;
5150                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
5151                         raid5_inc_bi_active_stripes(bi);
5152                         sh->overwrite_disks++;
5153                 }
5154                 spin_unlock_irq(&sh->stripe_lock);
5155                 if (conf->mddev->bitmap) {
5156                         for (d = 0;
5157                              d < conf->raid_disks - conf->max_degraded;
5158                              d++)
5159                                 bitmap_startwrite(mddev->bitmap,
5160                                                   sh->sector,
5161                                                   STRIPE_SECTORS,
5162                                                   0);
5163                         sh->bm_seq = conf->seq_flush + 1;
5164                         set_bit(STRIPE_BIT_DELAY, &sh->state);
5165                 }
5166
5167                 set_bit(STRIPE_HANDLE, &sh->state);
5168                 clear_bit(STRIPE_DELAYED, &sh->state);
5169                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5170                         atomic_inc(&conf->preread_active_stripes);
5171                 release_stripe_plug(mddev, sh);
5172         }
5173
5174         remaining = raid5_dec_bi_active_stripes(bi);
5175         if (remaining == 0) {
5176                 md_write_end(mddev);
5177                 bio_endio(bi);
5178         }
5179 }
5180
5181 static void make_request(struct mddev *mddev, struct bio * bi)
5182 {
5183         struct r5conf *conf = mddev->private;
5184         int dd_idx;
5185         sector_t new_sector;
5186         sector_t logical_sector, last_sector;
5187         struct stripe_head *sh;
5188         const int rw = bio_data_dir(bi);
5189         int remaining;
5190         DEFINE_WAIT(w);
5191         bool do_prepare;
5192
5193         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
5194                 int ret = r5l_handle_flush_request(conf->log, bi);
5195
5196                 if (ret == 0)
5197                         return;
5198                 if (ret == -ENODEV) {
5199                         md_flush_request(mddev, bi);
5200                         return;
5201                 }
5202                 /* ret == -EAGAIN, fallback */
5203         }
5204
5205         md_write_start(mddev, bi);
5206
5207         /*
5208          * If array is degraded, better not do chunk aligned read because
5209          * later we might have to read it again in order to reconstruct
5210          * data on failed drives.
5211          */
5212         if (rw == READ && mddev->degraded == 0 &&
5213             mddev->reshape_position == MaxSector) {
5214                 bi = chunk_aligned_read(mddev, bi);
5215                 if (!bi)
5216                         return;
5217         }
5218
5219         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
5220                 make_discard_request(mddev, bi);
5221                 return;
5222         }
5223
5224         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
5225         last_sector = bio_end_sector(bi);
5226         bi->bi_next = NULL;
5227         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
5228
5229         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
5230         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
5231                 int previous;
5232                 int seq;
5233
5234                 do_prepare = false;
5235         retry:
5236                 seq = read_seqcount_begin(&conf->gen_lock);
5237                 previous = 0;
5238                 if (do_prepare)
5239                         prepare_to_wait(&conf->wait_for_overlap, &w,
5240                                 TASK_UNINTERRUPTIBLE);
5241                 if (unlikely(conf->reshape_progress != MaxSector)) {
5242                         /* spinlock is needed as reshape_progress may be
5243                          * 64bit on a 32bit platform, and so it might be
5244                          * possible to see a half-updated value
5245                          * Of course reshape_progress could change after
5246                          * the lock is dropped, so once we get a reference
5247                          * to the stripe that we think it is, we will have
5248                          * to check again.
5249                          */
5250                         spin_lock_irq(&conf->device_lock);
5251                         if (mddev->reshape_backwards
5252                             ? logical_sector < conf->reshape_progress
5253                             : logical_sector >= conf->reshape_progress) {
5254                                 previous = 1;
5255                         } else {
5256                                 if (mddev->reshape_backwards
5257                                     ? logical_sector < conf->reshape_safe
5258                                     : logical_sector >= conf->reshape_safe) {
5259                                         spin_unlock_irq(&conf->device_lock);
5260                                         schedule();
5261                                         do_prepare = true;
5262                                         goto retry;
5263                                 }
5264                         }
5265                         spin_unlock_irq(&conf->device_lock);
5266                 }
5267
5268                 new_sector = raid5_compute_sector(conf, logical_sector,
5269                                                   previous,
5270                                                   &dd_idx, NULL);
5271                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
5272                         (unsigned long long)new_sector,
5273                         (unsigned long long)logical_sector);
5274
5275                 sh = raid5_get_active_stripe(conf, new_sector, previous,
5276                                        (bi->bi_rw&RWA_MASK), 0);
5277                 if (sh) {
5278                         if (unlikely(previous)) {
5279                                 /* expansion might have moved on while waiting for a
5280                                  * stripe, so we must do the range check again.
5281                                  * Expansion could still move past after this
5282                                  * test, but as we are holding a reference to
5283                                  * 'sh', we know that if that happens,
5284                                  *  STRIPE_EXPANDING will get set and the expansion
5285                                  * won't proceed until we finish with the stripe.
5286                                  */
5287                                 int must_retry = 0;
5288                                 spin_lock_irq(&conf->device_lock);
5289                                 if (mddev->reshape_backwards
5290                                     ? logical_sector >= conf->reshape_progress
5291                                     : logical_sector < conf->reshape_progress)
5292                                         /* mismatch, need to try again */
5293                                         must_retry = 1;
5294                                 spin_unlock_irq(&conf->device_lock);
5295                                 if (must_retry) {
5296                                         raid5_release_stripe(sh);
5297                                         schedule();
5298                                         do_prepare = true;
5299                                         goto retry;
5300                                 }
5301                         }
5302                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
5303                                 /* Might have got the wrong stripe_head
5304                                  * by accident
5305                                  */
5306                                 raid5_release_stripe(sh);
5307                                 goto retry;
5308                         }
5309
5310                         if (rw == WRITE &&
5311                             logical_sector >= mddev->suspend_lo &&
5312                             logical_sector < mddev->suspend_hi) {
5313                                 raid5_release_stripe(sh);
5314                                 /* As the suspend_* range is controlled by
5315                                  * userspace, we want an interruptible
5316                                  * wait.
5317                                  */
5318                                 prepare_to_wait(&conf->wait_for_overlap,
5319                                                 &w, TASK_INTERRUPTIBLE);
5320                                 if (logical_sector >= mddev->suspend_lo &&
5321                                     logical_sector < mddev->suspend_hi) {
5322                                         sigset_t full, old;
5323                                         sigfillset(&full);
5324                                         sigprocmask(SIG_BLOCK, &full, &old);
5325                                         schedule();
5326                                         sigprocmask(SIG_SETMASK, &old, NULL);
5327                                         do_prepare = true;
5328                                 }
5329                                 goto retry;
5330                         }
5331
5332                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
5333                             !add_stripe_bio(sh, bi, dd_idx, rw, previous)) {
5334                                 /* Stripe is busy expanding or
5335                                  * add failed due to overlap.  Flush everything
5336                                  * and wait a while
5337                                  */
5338                                 md_wakeup_thread(mddev->thread);
5339                                 raid5_release_stripe(sh);
5340                                 schedule();
5341                                 do_prepare = true;
5342                                 goto retry;
5343                         }
5344                         set_bit(STRIPE_HANDLE, &sh->state);
5345                         clear_bit(STRIPE_DELAYED, &sh->state);
5346                         if ((!sh->batch_head || sh == sh->batch_head) &&
5347                             (bi->bi_rw & REQ_SYNC) &&
5348                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
5349                                 atomic_inc(&conf->preread_active_stripes);
5350                         release_stripe_plug(mddev, sh);
5351                 } else {
5352                         /* cannot get stripe for read-ahead, just give-up */
5353                         bi->bi_error = -EIO;
5354                         break;
5355                 }
5356         }
5357         finish_wait(&conf->wait_for_overlap, &w);
5358
5359         remaining = raid5_dec_bi_active_stripes(bi);
5360         if (remaining == 0) {
5361
5362                 if ( rw == WRITE )
5363                         md_write_end(mddev);
5364
5365                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
5366                                          bi, 0);
5367                 bio_endio(bi);
5368         }
5369 }
5370
5371 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
5372
5373 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5374 {
5375         /* reshaping is quite different to recovery/resync so it is
5376          * handled quite separately ... here.
5377          *
5378          * On each call to sync_request, we gather one chunk worth of
5379          * destination stripes and flag them as expanding.
5380          * Then we find all the source stripes and request reads.
5381          * As the reads complete, handle_stripe will copy the data
5382          * into the destination stripe and release that stripe.
5383          */
5384         struct r5conf *conf = mddev->private;
5385         struct stripe_head *sh;
5386         sector_t first_sector, last_sector;
5387         int raid_disks = conf->previous_raid_disks;
5388         int data_disks = raid_disks - conf->max_degraded;
5389         int new_data_disks = conf->raid_disks - conf->max_degraded;
5390         int i;
5391         int dd_idx;
5392         sector_t writepos, readpos, safepos;
5393         sector_t stripe_addr;
5394         int reshape_sectors;
5395         struct list_head stripes;
5396         sector_t retn;
5397
5398         if (sector_nr == 0) {
5399                 /* If restarting in the middle, skip the initial sectors */
5400                 if (mddev->reshape_backwards &&
5401                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
5402                         sector_nr = raid5_size(mddev, 0, 0)
5403                                 - conf->reshape_progress;
5404                 } else if (mddev->reshape_backwards &&
5405                            conf->reshape_progress == MaxSector) {
5406                         /* shouldn't happen, but just in case, finish up.*/
5407                         sector_nr = MaxSector;
5408                 } else if (!mddev->reshape_backwards &&
5409                            conf->reshape_progress > 0)
5410                         sector_nr = conf->reshape_progress;
5411                 sector_div(sector_nr, new_data_disks);
5412                 if (sector_nr) {
5413                         mddev->curr_resync_completed = sector_nr;
5414                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5415                         *skipped = 1;
5416                         retn = sector_nr;
5417                         goto finish;
5418                 }
5419         }
5420
5421         /* We need to process a full chunk at a time.
5422          * If old and new chunk sizes differ, we need to process the
5423          * largest of these
5424          */
5425
5426         reshape_sectors = max(conf->chunk_sectors, conf->prev_chunk_sectors);
5427
5428         /* We update the metadata at least every 10 seconds, or when
5429          * the data about to be copied would over-write the source of
5430          * the data at the front of the range.  i.e. one new_stripe
5431          * along from reshape_progress new_maps to after where
5432          * reshape_safe old_maps to
5433          */
5434         writepos = conf->reshape_progress;
5435         sector_div(writepos, new_data_disks);
5436         readpos = conf->reshape_progress;
5437         sector_div(readpos, data_disks);
5438         safepos = conf->reshape_safe;
5439         sector_div(safepos, data_disks);
5440         if (mddev->reshape_backwards) {
5441                 BUG_ON(writepos < reshape_sectors);
5442                 writepos -= reshape_sectors;
5443                 readpos += reshape_sectors;
5444                 safepos += reshape_sectors;
5445         } else {
5446                 writepos += reshape_sectors;
5447                 /* readpos and safepos are worst-case calculations.
5448                  * A negative number is overly pessimistic, and causes
5449                  * obvious problems for unsigned storage.  So clip to 0.
5450                  */
5451                 readpos -= min_t(sector_t, reshape_sectors, readpos);
5452                 safepos -= min_t(sector_t, reshape_sectors, safepos);
5453         }
5454
5455         /* Having calculated the 'writepos' possibly use it
5456          * to set 'stripe_addr' which is where we will write to.
5457          */
5458         if (mddev->reshape_backwards) {
5459                 BUG_ON(conf->reshape_progress == 0);
5460                 stripe_addr = writepos;
5461                 BUG_ON((mddev->dev_sectors &
5462                         ~((sector_t)reshape_sectors - 1))
5463                        - reshape_sectors - stripe_addr
5464                        != sector_nr);
5465         } else {
5466                 BUG_ON(writepos != sector_nr + reshape_sectors);
5467                 stripe_addr = sector_nr;
5468         }
5469
5470         /* 'writepos' is the most advanced device address we might write.
5471          * 'readpos' is the least advanced device address we might read.
5472          * 'safepos' is the least address recorded in the metadata as having
5473          *     been reshaped.
5474          * If there is a min_offset_diff, these are adjusted either by
5475          * increasing the safepos/readpos if diff is negative, or
5476          * increasing writepos if diff is positive.
5477          * If 'readpos' is then behind 'writepos', there is no way that we can
5478          * ensure safety in the face of a crash - that must be done by userspace
5479          * making a backup of the data.  So in that case there is no particular
5480          * rush to update metadata.
5481          * Otherwise if 'safepos' is behind 'writepos', then we really need to
5482          * update the metadata to advance 'safepos' to match 'readpos' so that
5483          * we can be safe in the event of a crash.
5484          * So we insist on updating metadata if safepos is behind writepos and
5485          * readpos is beyond writepos.
5486          * In any case, update the metadata every 10 seconds.
5487          * Maybe that number should be configurable, but I'm not sure it is
5488          * worth it.... maybe it could be a multiple of safemode_delay???
5489          */
5490         if (conf->min_offset_diff < 0) {
5491                 safepos += -conf->min_offset_diff;
5492                 readpos += -conf->min_offset_diff;
5493         } else
5494                 writepos += conf->min_offset_diff;
5495
5496         if ((mddev->reshape_backwards
5497              ? (safepos > writepos && readpos < writepos)
5498              : (safepos < writepos && readpos > writepos)) ||
5499             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
5500                 /* Cannot proceed until we've updated the superblock... */
5501                 wait_event(conf->wait_for_overlap,
5502                            atomic_read(&conf->reshape_stripes)==0
5503                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5504                 if (atomic_read(&conf->reshape_stripes) != 0)
5505                         return 0;
5506                 mddev->reshape_position = conf->reshape_progress;
5507                 mddev->curr_resync_completed = sector_nr;
5508                 conf->reshape_checkpoint = jiffies;
5509                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
5510                 md_wakeup_thread(mddev->thread);
5511                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
5512                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5513                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5514                         return 0;
5515                 spin_lock_irq(&conf->device_lock);
5516                 conf->reshape_safe = mddev->reshape_position;
5517                 spin_unlock_irq(&conf->device_lock);
5518                 wake_up(&conf->wait_for_overlap);
5519                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5520         }
5521
5522         INIT_LIST_HEAD(&stripes);
5523         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
5524                 int j;
5525                 int skipped_disk = 0;
5526                 sh = raid5_get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
5527                 set_bit(STRIPE_EXPANDING, &sh->state);
5528                 atomic_inc(&conf->reshape_stripes);
5529                 /* If any of this stripe is beyond the end of the old
5530                  * array, then we need to zero those blocks
5531                  */
5532                 for (j=sh->disks; j--;) {
5533                         sector_t s;
5534                         if (j == sh->pd_idx)
5535                                 continue;
5536                         if (conf->level == 6 &&
5537                             j == sh->qd_idx)
5538                                 continue;
5539                         s = raid5_compute_blocknr(sh, j, 0);
5540                         if (s < raid5_size(mddev, 0, 0)) {
5541                                 skipped_disk = 1;
5542                                 continue;
5543                         }
5544                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
5545                         set_bit(R5_Expanded, &sh->dev[j].flags);
5546                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
5547                 }
5548                 if (!skipped_disk) {
5549                         set_bit(STRIPE_EXPAND_READY, &sh->state);
5550                         set_bit(STRIPE_HANDLE, &sh->state);
5551                 }
5552                 list_add(&sh->lru, &stripes);
5553         }
5554         spin_lock_irq(&conf->device_lock);
5555         if (mddev->reshape_backwards)
5556                 conf->reshape_progress -= reshape_sectors * new_data_disks;
5557         else
5558                 conf->reshape_progress += reshape_sectors * new_data_disks;
5559         spin_unlock_irq(&conf->device_lock);
5560         /* Ok, those stripe are ready. We can start scheduling
5561          * reads on the source stripes.
5562          * The source stripes are determined by mapping the first and last
5563          * block on the destination stripes.
5564          */
5565         first_sector =
5566                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
5567                                      1, &dd_idx, NULL);
5568         last_sector =
5569                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
5570                                             * new_data_disks - 1),
5571                                      1, &dd_idx, NULL);
5572         if (last_sector >= mddev->dev_sectors)
5573                 last_sector = mddev->dev_sectors - 1;
5574         while (first_sector <= last_sector) {
5575                 sh = raid5_get_active_stripe(conf, first_sector, 1, 0, 1);
5576                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
5577                 set_bit(STRIPE_HANDLE, &sh->state);
5578                 raid5_release_stripe(sh);
5579                 first_sector += STRIPE_SECTORS;
5580         }
5581         /* Now that the sources are clearly marked, we can release
5582          * the destination stripes
5583          */
5584         while (!list_empty(&stripes)) {
5585                 sh = list_entry(stripes.next, struct stripe_head, lru);
5586                 list_del_init(&sh->lru);
5587                 raid5_release_stripe(sh);
5588         }
5589         /* If this takes us to the resync_max point where we have to pause,
5590          * then we need to write out the superblock.
5591          */
5592         sector_nr += reshape_sectors;
5593         retn = reshape_sectors;
5594 finish:
5595         if (mddev->curr_resync_completed > mddev->resync_max ||
5596             (sector_nr - mddev->curr_resync_completed) * 2
5597             >= mddev->resync_max - mddev->curr_resync_completed) {
5598                 /* Cannot proceed until we've updated the superblock... */
5599                 wait_event(conf->wait_for_overlap,
5600                            atomic_read(&conf->reshape_stripes) == 0
5601                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5602                 if (atomic_read(&conf->reshape_stripes) != 0)
5603                         goto ret;
5604                 mddev->reshape_position = conf->reshape_progress;
5605                 mddev->curr_resync_completed = sector_nr;
5606                 conf->reshape_checkpoint = jiffies;
5607                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
5608                 md_wakeup_thread(mddev->thread);
5609                 wait_event(mddev->sb_wait,
5610                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
5611                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
5612                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
5613                         goto ret;
5614                 spin_lock_irq(&conf->device_lock);
5615                 conf->reshape_safe = mddev->reshape_position;
5616                 spin_unlock_irq(&conf->device_lock);
5617                 wake_up(&conf->wait_for_overlap);
5618                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
5619         }
5620 ret:
5621         return retn;
5622 }
5623
5624 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
5625 {
5626         struct r5conf *conf = mddev->private;
5627         struct stripe_head *sh;
5628         sector_t max_sector = mddev->dev_sectors;
5629         sector_t sync_blocks;
5630         int still_degraded = 0;
5631         int i;
5632
5633         if (sector_nr >= max_sector) {
5634                 /* just being told to finish up .. nothing much to do */
5635
5636                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5637                         end_reshape(conf);
5638                         return 0;
5639                 }
5640
5641                 if (mddev->curr_resync < max_sector) /* aborted */
5642                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5643                                         &sync_blocks, 1);
5644                 else /* completed sync */
5645                         conf->fullsync = 0;
5646                 bitmap_close_sync(mddev->bitmap);
5647
5648                 return 0;
5649         }
5650
5651         /* Allow raid5_quiesce to complete */
5652         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5653
5654         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5655                 return reshape_request(mddev, sector_nr, skipped);
5656
5657         /* No need to check resync_max as we never do more than one
5658          * stripe, and as resync_max will always be on a chunk boundary,
5659          * if the check in md_do_sync didn't fire, there is no chance
5660          * of overstepping resync_max here
5661          */
5662
5663         /* if there is too many failed drives and we are trying
5664          * to resync, then assert that we are finished, because there is
5665          * nothing we can do.
5666          */
5667         if (mddev->degraded >= conf->max_degraded &&
5668             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5669                 sector_t rv = mddev->dev_sectors - sector_nr;
5670                 *skipped = 1;
5671                 return rv;
5672         }
5673         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5674             !conf->fullsync &&
5675             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5676             sync_blocks >= STRIPE_SECTORS) {
5677                 /* we can skip this block, and probably more */
5678                 sync_blocks /= STRIPE_SECTORS;
5679                 *skipped = 1;
5680                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5681         }
5682
5683         bitmap_cond_end_sync(mddev->bitmap, sector_nr, false);
5684
5685         sh = raid5_get_active_stripe(conf, sector_nr, 0, 1, 0);
5686         if (sh == NULL) {
5687                 sh = raid5_get_active_stripe(conf, sector_nr, 0, 0, 0);
5688                 /* make sure we don't swamp the stripe cache if someone else
5689                  * is trying to get access
5690                  */
5691                 schedule_timeout_uninterruptible(1);
5692         }
5693         /* Need to check if array will still be degraded after recovery/resync
5694          * Note in case of > 1 drive failures it's possible we're rebuilding
5695          * one drive while leaving another faulty drive in array.
5696          */
5697         rcu_read_lock();
5698         for (i = 0; i < conf->raid_disks; i++) {
5699                 struct md_rdev *rdev = ACCESS_ONCE(conf->disks[i].rdev);
5700
5701                 if (rdev == NULL || test_bit(Faulty, &rdev->flags))
5702                         still_degraded = 1;
5703         }
5704         rcu_read_unlock();
5705
5706         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5707
5708         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5709         set_bit(STRIPE_HANDLE, &sh->state);
5710
5711         raid5_release_stripe(sh);
5712
5713         return STRIPE_SECTORS;
5714 }
5715
5716 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5717 {
5718         /* We may not be able to submit a whole bio at once as there
5719          * may not be enough stripe_heads available.
5720          * We cannot pre-allocate enough stripe_heads as we may need
5721          * more than exist in the cache (if we allow ever large chunks).
5722          * So we do one stripe head at a time and record in
5723          * ->bi_hw_segments how many have been done.
5724          *
5725          * We *know* that this entire raid_bio is in one chunk, so
5726          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5727          */
5728         struct stripe_head *sh;
5729         int dd_idx;
5730         sector_t sector, logical_sector, last_sector;
5731         int scnt = 0;
5732         int remaining;
5733         int handled = 0;
5734
5735         logical_sector = raid_bio->bi_iter.bi_sector &
5736                 ~((sector_t)STRIPE_SECTORS-1);
5737         sector = raid5_compute_sector(conf, logical_sector,
5738                                       0, &dd_idx, NULL);
5739         last_sector = bio_end_sector(raid_bio);
5740
5741         for (; logical_sector < last_sector;
5742              logical_sector += STRIPE_SECTORS,
5743                      sector += STRIPE_SECTORS,
5744                      scnt++) {
5745
5746                 if (scnt < raid5_bi_processed_stripes(raid_bio))
5747                         /* already done this stripe */
5748                         continue;
5749
5750                 sh = raid5_get_active_stripe(conf, sector, 0, 1, 1);
5751
5752                 if (!sh) {
5753                         /* failed to get a stripe - must wait */
5754                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5755                         conf->retry_read_aligned = raid_bio;
5756                         return handled;
5757                 }
5758
5759                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0, 0)) {
5760                         raid5_release_stripe(sh);
5761                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5762                         conf->retry_read_aligned = raid_bio;
5763                         return handled;
5764                 }
5765
5766                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5767                 handle_stripe(sh);
5768                 raid5_release_stripe(sh);
5769                 handled++;
5770         }
5771         remaining = raid5_dec_bi_active_stripes(raid_bio);
5772         if (remaining == 0) {
5773                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5774                                          raid_bio, 0);
5775                 bio_endio(raid_bio);
5776         }
5777         if (atomic_dec_and_test(&conf->active_aligned_reads))
5778                 wake_up(&conf->wait_for_quiescent);
5779         return handled;
5780 }
5781
5782 static int handle_active_stripes(struct r5conf *conf, int group,
5783                                  struct r5worker *worker,
5784                                  struct list_head *temp_inactive_list)
5785 {
5786         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5787         int i, batch_size = 0, hash;
5788         bool release_inactive = false;
5789
5790         while (batch_size < MAX_STRIPE_BATCH &&
5791                         (sh = __get_priority_stripe(conf, group)) != NULL)
5792                 batch[batch_size++] = sh;
5793
5794         if (batch_size == 0) {
5795                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5796                         if (!list_empty(temp_inactive_list + i))
5797                                 break;
5798                 if (i == NR_STRIPE_HASH_LOCKS) {
5799                         spin_unlock_irq(&conf->device_lock);
5800                         r5l_flush_stripe_to_raid(conf->log);
5801                         spin_lock_irq(&conf->device_lock);
5802                         return batch_size;
5803                 }
5804                 release_inactive = true;
5805         }
5806         spin_unlock_irq(&conf->device_lock);
5807
5808         release_inactive_stripe_list(conf, temp_inactive_list,
5809                                      NR_STRIPE_HASH_LOCKS);
5810
5811         r5l_flush_stripe_to_raid(conf->log);
5812         if (release_inactive) {
5813                 spin_lock_irq(&conf->device_lock);
5814                 return 0;
5815         }
5816
5817         for (i = 0; i < batch_size; i++)
5818                 handle_stripe(batch[i]);
5819         r5l_write_stripe_run(conf->log);
5820
5821         cond_resched();
5822
5823         spin_lock_irq(&conf->device_lock);
5824         for (i = 0; i < batch_size; i++) {
5825                 hash = batch[i]->hash_lock_index;
5826                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5827         }
5828         return batch_size;
5829 }
5830
5831 static void raid5_do_work(struct work_struct *work)
5832 {
5833         struct r5worker *worker = container_of(work, struct r5worker, work);
5834         struct r5worker_group *group = worker->group;
5835         struct r5conf *conf = group->conf;
5836         int group_id = group - conf->worker_groups;
5837         int handled;
5838         struct blk_plug plug;
5839
5840         pr_debug("+++ raid5worker active\n");
5841
5842         blk_start_plug(&plug);
5843         handled = 0;
5844         spin_lock_irq(&conf->device_lock);
5845         while (1) {
5846                 int batch_size, released;
5847
5848                 released = release_stripe_list(conf, worker->temp_inactive_list);
5849
5850                 batch_size = handle_active_stripes(conf, group_id, worker,
5851                                                    worker->temp_inactive_list);
5852                 worker->working = false;
5853                 if (!batch_size && !released)
5854                         break;
5855                 handled += batch_size;
5856         }
5857         pr_debug("%d stripes handled\n", handled);
5858
5859         spin_unlock_irq(&conf->device_lock);
5860
5861         r5l_flush_stripe_to_raid(conf->log);
5862
5863         async_tx_issue_pending_all();
5864         blk_finish_plug(&plug);
5865
5866         pr_debug("--- raid5worker inactive\n");
5867 }
5868
5869 /*
5870  * This is our raid5 kernel thread.
5871  *
5872  * We scan the hash table for stripes which can be handled now.
5873  * During the scan, completed stripes are saved for us by the interrupt
5874  * handler, so that they will not have to wait for our next wakeup.
5875  */
5876 static void raid5d(struct md_thread *thread)
5877 {
5878         struct mddev *mddev = thread->mddev;
5879         struct r5conf *conf = mddev->private;
5880         int handled;
5881         struct blk_plug plug;
5882
5883         pr_debug("+++ raid5d active\n");
5884
5885         md_check_recovery(mddev);
5886
5887         if (!bio_list_empty(&conf->return_bi) &&
5888             !test_bit(MD_CHANGE_PENDING, &mddev->flags)) {
5889                 struct bio_list tmp = BIO_EMPTY_LIST;
5890                 spin_lock_irq(&conf->device_lock);
5891                 if (!test_bit(MD_CHANGE_PENDING, &mddev->flags)) {
5892                         bio_list_merge(&tmp, &conf->return_bi);
5893                         bio_list_init(&conf->return_bi);
5894                 }
5895                 spin_unlock_irq(&conf->device_lock);
5896                 return_io(&tmp);
5897         }
5898
5899         blk_start_plug(&plug);
5900         handled = 0;
5901         spin_lock_irq(&conf->device_lock);
5902         while (1) {
5903                 struct bio *bio;
5904                 int batch_size, released;
5905
5906                 released = release_stripe_list(conf, conf->temp_inactive_list);
5907                 if (released)
5908                         clear_bit(R5_DID_ALLOC, &conf->cache_state);
5909
5910                 if (
5911                     !list_empty(&conf->bitmap_list)) {
5912                         /* Now is a good time to flush some bitmap updates */
5913                         conf->seq_flush++;
5914                         spin_unlock_irq(&conf->device_lock);
5915                         bitmap_unplug(mddev->bitmap);
5916                         spin_lock_irq(&conf->device_lock);
5917                         conf->seq_write = conf->seq_flush;
5918                         activate_bit_delay(conf, conf->temp_inactive_list);
5919                 }
5920                 raid5_activate_delayed(conf);
5921
5922                 while ((bio = remove_bio_from_retry(conf))) {
5923                         int ok;
5924                         spin_unlock_irq(&conf->device_lock);
5925                         ok = retry_aligned_read(conf, bio);
5926                         spin_lock_irq(&conf->device_lock);
5927                         if (!ok)
5928                                 break;
5929                         handled++;
5930                 }
5931
5932                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
5933                                                    conf->temp_inactive_list);
5934                 if (!batch_size && !released)
5935                         break;
5936                 handled += batch_size;
5937
5938                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
5939                         spin_unlock_irq(&conf->device_lock);
5940                         md_check_recovery(mddev);
5941                         spin_lock_irq(&conf->device_lock);
5942                 }
5943         }
5944         pr_debug("%d stripes handled\n", handled);
5945
5946         spin_unlock_irq(&conf->device_lock);
5947         if (test_and_clear_bit(R5_ALLOC_MORE, &conf->cache_state) &&
5948             mutex_trylock(&conf->cache_size_mutex)) {
5949                 grow_one_stripe(conf, __GFP_NOWARN);
5950                 /* Set flag even if allocation failed.  This helps
5951                  * slow down allocation requests when mem is short
5952                  */
5953                 set_bit(R5_DID_ALLOC, &conf->cache_state);
5954                 mutex_unlock(&conf->cache_size_mutex);
5955         }
5956
5957         r5l_flush_stripe_to_raid(conf->log);
5958
5959         async_tx_issue_pending_all();
5960         blk_finish_plug(&plug);
5961
5962         pr_debug("--- raid5d inactive\n");
5963 }
5964
5965 static ssize_t
5966 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
5967 {
5968         struct r5conf *conf;
5969         int ret = 0;
5970         spin_lock(&mddev->lock);
5971         conf = mddev->private;
5972         if (conf)
5973                 ret = sprintf(page, "%d\n", conf->min_nr_stripes);
5974         spin_unlock(&mddev->lock);
5975         return ret;
5976 }
5977
5978 int
5979 raid5_set_cache_size(struct mddev *mddev, int size)
5980 {
5981         struct r5conf *conf = mddev->private;
5982         int err;
5983
5984         if (size <= 16 || size > 32768)
5985                 return -EINVAL;
5986
5987         conf->min_nr_stripes = size;
5988         mutex_lock(&conf->cache_size_mutex);
5989         while (size < conf->max_nr_stripes &&
5990                drop_one_stripe(conf))
5991                 ;
5992         mutex_unlock(&conf->cache_size_mutex);
5993
5994
5995         err = md_allow_write(mddev);
5996         if (err)
5997                 return err;
5998
5999         mutex_lock(&conf->cache_size_mutex);
6000         while (size > conf->max_nr_stripes)
6001                 if (!grow_one_stripe(conf, GFP_KERNEL))
6002                         break;
6003         mutex_unlock(&conf->cache_size_mutex);
6004
6005         return 0;
6006 }
6007 EXPORT_SYMBOL(raid5_set_cache_size);
6008
6009 static ssize_t
6010 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
6011 {
6012         struct r5conf *conf;
6013         unsigned long new;
6014         int err;
6015
6016         if (len >= PAGE_SIZE)
6017                 return -EINVAL;
6018         if (kstrtoul(page, 10, &new))
6019                 return -EINVAL;
6020         err = mddev_lock(mddev);
6021         if (err)
6022                 return err;
6023         conf = mddev->private;
6024         if (!conf)
6025                 err = -ENODEV;
6026         else
6027                 err = raid5_set_cache_size(mddev, new);
6028         mddev_unlock(mddev);
6029
6030         return err ?: len;
6031 }
6032
6033 static struct md_sysfs_entry
6034 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
6035                                 raid5_show_stripe_cache_size,
6036                                 raid5_store_stripe_cache_size);
6037
6038 static ssize_t
6039 raid5_show_rmw_level(struct mddev  *mddev, char *page)
6040 {
6041         struct r5conf *conf = mddev->private;
6042         if (conf)
6043                 return sprintf(page, "%d\n", conf->rmw_level);
6044         else
6045                 return 0;
6046 }
6047
6048 static ssize_t
6049 raid5_store_rmw_level(struct mddev  *mddev, const char *page, size_t len)
6050 {
6051         struct r5conf *conf = mddev->private;
6052         unsigned long new;
6053
6054         if (!conf)
6055                 return -ENODEV;
6056
6057         if (len >= PAGE_SIZE)
6058                 return -EINVAL;
6059
6060         if (kstrtoul(page, 10, &new))
6061                 return -EINVAL;
6062
6063         if (new != PARITY_DISABLE_RMW && !raid6_call.xor_syndrome)
6064                 return -EINVAL;
6065
6066         if (new != PARITY_DISABLE_RMW &&
6067             new != PARITY_ENABLE_RMW &&
6068             new != PARITY_PREFER_RMW)
6069                 return -EINVAL;
6070
6071         conf->rmw_level = new;
6072         return len;
6073 }
6074
6075 static struct md_sysfs_entry
6076 raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR,
6077                          raid5_show_rmw_level,
6078                          raid5_store_rmw_level);
6079
6080
6081 static ssize_t
6082 raid5_show_preread_threshold(struct mddev *mddev, char *page)
6083 {
6084         struct r5conf *conf;
6085         int ret = 0;
6086         spin_lock(&mddev->lock);
6087         conf = mddev->private;
6088         if (conf)
6089                 ret = sprintf(page, "%d\n", conf->bypass_threshold);
6090         spin_unlock(&mddev->lock);
6091         return ret;
6092 }
6093
6094 static ssize_t
6095 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
6096 {
6097         struct r5conf *conf;
6098         unsigned long new;
6099         int err;
6100
6101         if (len >= PAGE_SIZE)
6102                 return -EINVAL;
6103         if (kstrtoul(page, 10, &new))
6104                 return -EINVAL;
6105
6106         err = mddev_lock(mddev);
6107         if (err)
6108                 return err;
6109         conf = mddev->private;
6110         if (!conf)
6111                 err = -ENODEV;
6112         else if (new > conf->min_nr_stripes)
6113                 err = -EINVAL;
6114         else
6115                 conf->bypass_threshold = new;
6116         mddev_unlock(mddev);
6117         return err ?: len;
6118 }
6119
6120 static struct md_sysfs_entry
6121 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
6122                                         S_IRUGO | S_IWUSR,
6123                                         raid5_show_preread_threshold,
6124                                         raid5_store_preread_threshold);
6125
6126 static ssize_t
6127 raid5_show_skip_copy(struct mddev *mddev, char *page)
6128 {
6129         struct r5conf *conf;
6130         int ret = 0;
6131         spin_lock(&mddev->lock);
6132         conf = mddev->private;
6133         if (conf)
6134                 ret = sprintf(page, "%d\n", conf->skip_copy);
6135         spin_unlock(&mddev->lock);
6136         return ret;
6137 }
6138
6139 static ssize_t
6140 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
6141 {
6142         struct r5conf *conf;
6143         unsigned long new;
6144         int err;
6145
6146         if (len >= PAGE_SIZE)
6147                 return -EINVAL;
6148         if (kstrtoul(page, 10, &new))
6149                 return -EINVAL;
6150         new = !!new;
6151
6152         err = mddev_lock(mddev);
6153         if (err)
6154                 return err;
6155         conf = mddev->private;
6156         if (!conf)
6157                 err = -ENODEV;
6158         else if (new != conf->skip_copy) {
6159                 mddev_suspend(mddev);
6160                 conf->skip_copy = new;
6161                 if (new)
6162                         mddev->queue->backing_dev_info.capabilities |=
6163                                 BDI_CAP_STABLE_WRITES;
6164                 else
6165                         mddev->queue->backing_dev_info.capabilities &=
6166                                 ~BDI_CAP_STABLE_WRITES;
6167                 mddev_resume(mddev);
6168         }
6169         mddev_unlock(mddev);
6170         return err ?: len;
6171 }
6172
6173 static struct md_sysfs_entry
6174 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
6175                                         raid5_show_skip_copy,
6176                                         raid5_store_skip_copy);
6177
6178 static ssize_t
6179 stripe_cache_active_show(struct mddev *mddev, char *page)
6180 {
6181         struct r5conf *conf = mddev->private;
6182         if (conf)
6183                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
6184         else
6185                 return 0;
6186 }
6187
6188 static struct md_sysfs_entry
6189 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
6190
6191 static ssize_t
6192 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
6193 {
6194         struct r5conf *conf;
6195         int ret = 0;
6196         spin_lock(&mddev->lock);
6197         conf = mddev->private;
6198         if (conf)
6199                 ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);
6200         spin_unlock(&mddev->lock);
6201         return ret;
6202 }
6203
6204 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6205                                int *group_cnt,
6206                                int *worker_cnt_per_group,
6207                                struct r5worker_group **worker_groups);
6208 static ssize_t
6209 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
6210 {
6211         struct r5conf *conf;
6212         unsigned long new;
6213         int err;
6214         struct r5worker_group *new_groups, *old_groups;
6215         int group_cnt, worker_cnt_per_group;
6216
6217         if (len >= PAGE_SIZE)
6218                 return -EINVAL;
6219         if (kstrtoul(page, 10, &new))
6220                 return -EINVAL;
6221
6222         err = mddev_lock(mddev);
6223         if (err)
6224                 return err;
6225         conf = mddev->private;
6226         if (!conf)
6227                 err = -ENODEV;
6228         else if (new != conf->worker_cnt_per_group) {
6229                 mddev_suspend(mddev);
6230
6231                 old_groups = conf->worker_groups;
6232                 if (old_groups)
6233                         flush_workqueue(raid5_wq);
6234
6235                 err = alloc_thread_groups(conf, new,
6236                                           &group_cnt, &worker_cnt_per_group,
6237                                           &new_groups);
6238                 if (!err) {
6239                         spin_lock_irq(&conf->device_lock);
6240                         conf->group_cnt = group_cnt;
6241                         conf->worker_cnt_per_group = worker_cnt_per_group;
6242                         conf->worker_groups = new_groups;
6243                         spin_unlock_irq(&conf->device_lock);
6244
6245                         if (old_groups)
6246                                 kfree(old_groups[0].workers);
6247                         kfree(old_groups);
6248                 }
6249                 mddev_resume(mddev);
6250         }
6251         mddev_unlock(mddev);
6252
6253         return err ?: len;
6254 }
6255
6256 static struct md_sysfs_entry
6257 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
6258                                 raid5_show_group_thread_cnt,
6259                                 raid5_store_group_thread_cnt);
6260
6261 static struct attribute *raid5_attrs[] =  {
6262         &raid5_stripecache_size.attr,
6263         &raid5_stripecache_active.attr,
6264         &raid5_preread_bypass_threshold.attr,
6265         &raid5_group_thread_cnt.attr,
6266         &raid5_skip_copy.attr,
6267         &raid5_rmw_level.attr,
6268         NULL,
6269 };
6270 static struct attribute_group raid5_attrs_group = {
6271         .name = NULL,
6272         .attrs = raid5_attrs,
6273 };
6274
6275 static int alloc_thread_groups(struct r5conf *conf, int cnt,
6276                                int *group_cnt,
6277                                int *worker_cnt_per_group,
6278                                struct r5worker_group **worker_groups)
6279 {
6280         int i, j, k;
6281         ssize_t size;
6282         struct r5worker *workers;
6283
6284         *worker_cnt_per_group = cnt;
6285         if (cnt == 0) {
6286                 *group_cnt = 0;
6287                 *worker_groups = NULL;
6288                 return 0;
6289         }
6290         *group_cnt = num_possible_nodes();
6291         size = sizeof(struct r5worker) * cnt;
6292         workers = kzalloc(size * *group_cnt, GFP_NOIO);
6293         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
6294                                 *group_cnt, GFP_NOIO);
6295         if (!*worker_groups || !workers) {
6296                 kfree(workers);
6297                 kfree(*worker_groups);
6298                 return -ENOMEM;
6299         }
6300
6301         for (i = 0; i < *group_cnt; i++) {
6302                 struct r5worker_group *group;
6303
6304                 group = &(*worker_groups)[i];
6305                 INIT_LIST_HEAD(&group->handle_list);
6306                 group->conf = conf;
6307                 group->workers = workers + i * cnt;
6308
6309                 for (j = 0; j < cnt; j++) {
6310                         struct r5worker *worker = group->workers + j;
6311                         worker->group = group;
6312                         INIT_WORK(&worker->work, raid5_do_work);
6313
6314                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
6315                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
6316                 }
6317         }
6318
6319         return 0;
6320 }
6321
6322 static void free_thread_groups(struct r5conf *conf)
6323 {
6324         if (conf->worker_groups)
6325                 kfree(conf->worker_groups[0].workers);
6326         kfree(conf->worker_groups);
6327         conf->worker_groups = NULL;
6328 }
6329
6330 static sector_t
6331 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
6332 {
6333         struct r5conf *conf = mddev->private;
6334
6335         if (!sectors)
6336                 sectors = mddev->dev_sectors;
6337         if (!raid_disks)
6338                 /* size is defined by the smallest of previous and new size */
6339                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
6340
6341         sectors &= ~((sector_t)conf->chunk_sectors - 1);
6342         sectors &= ~((sector_t)conf->prev_chunk_sectors - 1);
6343         return sectors * (raid_disks - conf->max_degraded);
6344 }
6345
6346 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6347 {
6348         safe_put_page(percpu->spare_page);
6349         if (percpu->scribble)
6350                 flex_array_free(percpu->scribble);
6351         percpu->spare_page = NULL;
6352         percpu->scribble = NULL;
6353 }
6354
6355 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
6356 {
6357         if (conf->level == 6 && !percpu->spare_page)
6358                 percpu->spare_page = alloc_page(GFP_KERNEL);
6359         if (!percpu->scribble)
6360                 percpu->scribble = scribble_alloc(max(conf->raid_disks,
6361                                                       conf->previous_raid_disks),
6362                                                   max(conf->chunk_sectors,
6363                                                       conf->prev_chunk_sectors)
6364                                                    / STRIPE_SECTORS,
6365                                                   GFP_KERNEL);
6366
6367         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
6368                 free_scratch_buffer(conf, percpu);
6369                 return -ENOMEM;
6370         }
6371
6372         return 0;
6373 }
6374
6375 static void raid5_free_percpu(struct r5conf *conf)
6376 {
6377         unsigned long cpu;
6378
6379         if (!conf->percpu)
6380                 return;
6381
6382 #ifdef CONFIG_HOTPLUG_CPU
6383         unregister_cpu_notifier(&conf->cpu_notify);
6384 #endif
6385
6386         get_online_cpus();
6387         for_each_possible_cpu(cpu)
6388                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6389         put_online_cpus();
6390
6391         free_percpu(conf->percpu);
6392 }
6393
6394 static void free_conf(struct r5conf *conf)
6395 {
6396         if (conf->log)
6397                 r5l_exit_log(conf->log);
6398         if (conf->shrinker.seeks)
6399                 unregister_shrinker(&conf->shrinker);
6400
6401         free_thread_groups(conf);
6402         shrink_stripes(conf);
6403         raid5_free_percpu(conf);
6404         kfree(conf->disks);
6405         kfree(conf->stripe_hashtbl);
6406         kfree(conf);
6407 }
6408
6409 #ifdef CONFIG_HOTPLUG_CPU
6410 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
6411                               void *hcpu)
6412 {
6413         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
6414         long cpu = (long)hcpu;
6415         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
6416
6417         switch (action) {
6418         case CPU_UP_PREPARE:
6419         case CPU_UP_PREPARE_FROZEN:
6420                 if (alloc_scratch_buffer(conf, percpu)) {
6421                         pr_err("%s: failed memory allocation for cpu%ld\n",
6422                                __func__, cpu);
6423                         return notifier_from_errno(-ENOMEM);
6424                 }
6425                 break;
6426         case CPU_DEAD:
6427         case CPU_DEAD_FROZEN:
6428                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6429                 break;
6430         default:
6431                 break;
6432         }
6433         return NOTIFY_OK;
6434 }
6435 #endif
6436
6437 static int raid5_alloc_percpu(struct r5conf *conf)
6438 {
6439         unsigned long cpu;
6440         int err = 0;
6441
6442         conf->percpu = alloc_percpu(struct raid5_percpu);
6443         if (!conf->percpu)
6444                 return -ENOMEM;
6445
6446 #ifdef CONFIG_HOTPLUG_CPU
6447         conf->cpu_notify.notifier_call = raid456_cpu_notify;
6448         conf->cpu_notify.priority = 0;
6449         err = register_cpu_notifier(&conf->cpu_notify);
6450         if (err)
6451                 return err;
6452 #endif
6453
6454         get_online_cpus();
6455         for_each_present_cpu(cpu) {
6456                 err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
6457                 if (err) {
6458                         pr_err("%s: failed memory allocation for cpu%ld\n",
6459                                __func__, cpu);
6460                         break;
6461                 }
6462         }
6463         put_online_cpus();
6464
6465         if (!err) {
6466                 conf->scribble_disks = max(conf->raid_disks,
6467                         conf->previous_raid_disks);
6468                 conf->scribble_sectors = max(conf->chunk_sectors,
6469                         conf->prev_chunk_sectors);
6470         }
6471         return err;
6472 }
6473
6474 static unsigned long raid5_cache_scan(struct shrinker *shrink,
6475                                       struct shrink_control *sc)
6476 {
6477         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6478         unsigned long ret = SHRINK_STOP;
6479
6480         if (mutex_trylock(&conf->cache_size_mutex)) {
6481                 ret= 0;
6482                 while (ret < sc->nr_to_scan &&
6483                        conf->max_nr_stripes > conf->min_nr_stripes) {
6484                         if (drop_one_stripe(conf) == 0) {
6485                                 ret = SHRINK_STOP;
6486                                 break;
6487                         }
6488                         ret++;
6489                 }
6490                 mutex_unlock(&conf->cache_size_mutex);
6491         }
6492         return ret;
6493 }
6494
6495 static unsigned long raid5_cache_count(struct shrinker *shrink,
6496                                        struct shrink_control *sc)
6497 {
6498         struct r5conf *conf = container_of(shrink, struct r5conf, shrinker);
6499
6500         if (conf->max_nr_stripes < conf->min_nr_stripes)
6501                 /* unlikely, but not impossible */
6502                 return 0;
6503         return conf->max_nr_stripes - conf->min_nr_stripes;
6504 }
6505
6506 static struct r5conf *setup_conf(struct mddev *mddev)
6507 {
6508         struct r5conf *conf;
6509         int raid_disk, memory, max_disks;
6510         struct md_rdev *rdev;
6511         struct disk_info *disk;
6512         char pers_name[6];
6513         int i;
6514         int group_cnt, worker_cnt_per_group;
6515         struct r5worker_group *new_group;
6516
6517         if (mddev->new_level != 5
6518             && mddev->new_level != 4
6519             && mddev->new_level != 6) {
6520                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
6521                        mdname(mddev), mddev->new_level);
6522                 return ERR_PTR(-EIO);
6523         }
6524         if ((mddev->new_level == 5
6525              && !algorithm_valid_raid5(mddev->new_layout)) ||
6526             (mddev->new_level == 6
6527              && !algorithm_valid_raid6(mddev->new_layout))) {
6528                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
6529                        mdname(mddev), mddev->new_layout);
6530                 return ERR_PTR(-EIO);
6531         }
6532         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
6533                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
6534                        mdname(mddev), mddev->raid_disks);
6535                 return ERR_PTR(-EINVAL);
6536         }
6537
6538         if (!mddev->new_chunk_sectors ||
6539             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
6540             !is_power_of_2(mddev->new_chunk_sectors)) {
6541                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
6542                        mdname(mddev), mddev->new_chunk_sectors << 9);
6543                 return ERR_PTR(-EINVAL);
6544         }
6545
6546         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
6547         if (conf == NULL)
6548                 goto abort;
6549         /* Don't enable multi-threading by default*/
6550         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
6551                                  &new_group)) {
6552                 conf->group_cnt = group_cnt;
6553                 conf->worker_cnt_per_group = worker_cnt_per_group;
6554                 conf->worker_groups = new_group;
6555         } else
6556                 goto abort;
6557         spin_lock_init(&conf->device_lock);
6558         seqcount_init(&conf->gen_lock);
6559         mutex_init(&conf->cache_size_mutex);
6560         init_waitqueue_head(&conf->wait_for_quiescent);
6561         init_waitqueue_head(&conf->wait_for_stripe);
6562         init_waitqueue_head(&conf->wait_for_overlap);
6563         INIT_LIST_HEAD(&conf->handle_list);
6564         INIT_LIST_HEAD(&conf->hold_list);
6565         INIT_LIST_HEAD(&conf->delayed_list);
6566         INIT_LIST_HEAD(&conf->bitmap_list);
6567         bio_list_init(&conf->return_bi);
6568         init_llist_head(&conf->released_stripes);
6569         atomic_set(&conf->active_stripes, 0);
6570         atomic_set(&conf->preread_active_stripes, 0);
6571         atomic_set(&conf->active_aligned_reads, 0);
6572         conf->bypass_threshold = BYPASS_THRESHOLD;
6573         conf->recovery_disabled = mddev->recovery_disabled - 1;
6574
6575         conf->raid_disks = mddev->raid_disks;
6576         if (mddev->reshape_position == MaxSector)
6577                 conf->previous_raid_disks = mddev->raid_disks;
6578         else
6579                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
6580         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
6581
6582         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
6583                               GFP_KERNEL);
6584         if (!conf->disks)
6585                 goto abort;
6586
6587         conf->mddev = mddev;
6588
6589         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
6590                 goto abort;
6591
6592         /* We init hash_locks[0] separately to that it can be used
6593          * as the reference lock in the spin_lock_nest_lock() call
6594          * in lock_all_device_hash_locks_irq in order to convince
6595          * lockdep that we know what we are doing.
6596          */
6597         spin_lock_init(conf->hash_locks);
6598         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
6599                 spin_lock_init(conf->hash_locks + i);
6600
6601         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6602                 INIT_LIST_HEAD(conf->inactive_list + i);
6603
6604         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
6605                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
6606
6607         conf->level = mddev->new_level;
6608         conf->chunk_sectors = mddev->new_chunk_sectors;
6609         if (raid5_alloc_percpu(conf) != 0)
6610                 goto abort;
6611
6612         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
6613
6614         rdev_for_each(rdev, mddev) {
6615                 raid_disk = rdev->raid_disk;
6616                 if (raid_disk >= max_disks
6617                     || raid_disk < 0 || test_bit(Journal, &rdev->flags))
6618                         continue;
6619                 disk = conf->disks + raid_disk;
6620
6621                 if (test_bit(Replacement, &rdev->flags)) {
6622                         if (disk->replacement)
6623                                 goto abort;
6624                         disk->replacement = rdev;
6625                 } else {
6626                         if (disk->rdev)
6627                                 goto abort;
6628                         disk->rdev = rdev;
6629                 }
6630
6631                 if (test_bit(In_sync, &rdev->flags)) {
6632                         char b[BDEVNAME_SIZE];
6633                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
6634                                " disk %d\n",
6635                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
6636                 } else if (rdev->saved_raid_disk != raid_disk)
6637                         /* Cannot rely on bitmap to complete recovery */
6638                         conf->fullsync = 1;
6639         }
6640
6641         conf->level = mddev->new_level;
6642         if (conf->level == 6) {
6643                 conf->max_degraded = 2;
6644                 if (raid6_call.xor_syndrome)
6645                         conf->rmw_level = PARITY_ENABLE_RMW;
6646                 else
6647                         conf->rmw_level = PARITY_DISABLE_RMW;
6648         } else {
6649                 conf->max_degraded = 1;
6650                 conf->rmw_level = PARITY_ENABLE_RMW;
6651         }
6652         conf->algorithm = mddev->new_layout;
6653         conf->reshape_progress = mddev->reshape_position;
6654         if (conf->reshape_progress != MaxSector) {
6655                 conf->prev_chunk_sectors = mddev->chunk_sectors;
6656                 conf->prev_algo = mddev->layout;
6657         } else {
6658                 conf->prev_chunk_sectors = conf->chunk_sectors;
6659                 conf->prev_algo = conf->algorithm;
6660         }
6661
6662         conf->min_nr_stripes = NR_STRIPES;
6663         memory = conf->min_nr_stripes * (sizeof(struct stripe_head) +
6664                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
6665         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
6666         if (grow_stripes(conf, conf->min_nr_stripes)) {
6667                 printk(KERN_ERR
6668                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
6669                        mdname(mddev), memory);
6670                 goto abort;
6671         } else
6672                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
6673                        mdname(mddev), memory);
6674         /*
6675          * Losing a stripe head costs more than the time to refill it,
6676          * it reduces the queue depth and so can hurt throughput.
6677          * So set it rather large, scaled by number of devices.
6678          */
6679         conf->shrinker.seeks = DEFAULT_SEEKS * conf->raid_disks * 4;
6680         conf->shrinker.scan_objects = raid5_cache_scan;
6681         conf->shrinker.count_objects = raid5_cache_count;
6682         conf->shrinker.batch = 128;
6683         conf->shrinker.flags = 0;
6684         register_shrinker(&conf->shrinker);
6685
6686         sprintf(pers_name, "raid%d", mddev->new_level);
6687         conf->thread = md_register_thread(raid5d, mddev, pers_name);
6688         if (!conf->thread) {
6689                 printk(KERN_ERR
6690                        "md/raid:%s: couldn't allocate thread.\n",
6691                        mdname(mddev));
6692                 goto abort;
6693         }
6694
6695         return conf;
6696
6697  abort:
6698         if (conf) {
6699                 free_conf(conf);
6700                 return ERR_PTR(-EIO);
6701         } else
6702                 return ERR_PTR(-ENOMEM);
6703 }
6704
6705 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
6706 {
6707         switch (algo) {
6708         case ALGORITHM_PARITY_0:
6709                 if (raid_disk < max_degraded)
6710                         return 1;
6711                 break;
6712         case ALGORITHM_PARITY_N:
6713                 if (raid_disk >= raid_disks - max_degraded)
6714                         return 1;
6715                 break;
6716         case ALGORITHM_PARITY_0_6:
6717                 if (raid_disk == 0 ||
6718                     raid_disk == raid_disks - 1)
6719                         return 1;
6720                 break;
6721         case ALGORITHM_LEFT_ASYMMETRIC_6:
6722         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6723         case ALGORITHM_LEFT_SYMMETRIC_6:
6724         case ALGORITHM_RIGHT_SYMMETRIC_6:
6725                 if (raid_disk == raid_disks - 1)
6726                         return 1;
6727         }
6728         return 0;
6729 }
6730
6731 static int run(struct mddev *mddev)
6732 {
6733         struct r5conf *conf;
6734         int working_disks = 0;
6735         int dirty_parity_disks = 0;
6736         struct md_rdev *rdev;
6737         struct md_rdev *journal_dev = NULL;
6738         sector_t reshape_offset = 0;
6739         int i;
6740         long long min_offset_diff = 0;
6741         int first = 1;
6742
6743         if (mddev->recovery_cp != MaxSector)
6744                 printk(KERN_NOTICE "md/raid:%s: not clean"
6745                        " -- starting background reconstruction\n",
6746                        mdname(mddev));
6747
6748         rdev_for_each(rdev, mddev) {
6749                 long long diff;
6750
6751                 if (test_bit(Journal, &rdev->flags)) {
6752                         journal_dev = rdev;
6753                         continue;
6754                 }
6755                 if (rdev->raid_disk < 0)
6756                         continue;
6757                 diff = (rdev->new_data_offset - rdev->data_offset);
6758                 if (first) {
6759                         min_offset_diff = diff;
6760                         first = 0;
6761                 } else if (mddev->reshape_backwards &&
6762                          diff < min_offset_diff)
6763                         min_offset_diff = diff;
6764                 else if (!mddev->reshape_backwards &&
6765                          diff > min_offset_diff)
6766                         min_offset_diff = diff;
6767         }
6768
6769         if (mddev->reshape_position != MaxSector) {
6770                 /* Check that we can continue the reshape.
6771                  * Difficulties arise if the stripe we would write to
6772                  * next is at or after the stripe we would read from next.
6773                  * For a reshape that changes the number of devices, this
6774                  * is only possible for a very short time, and mdadm makes
6775                  * sure that time appears to have past before assembling
6776                  * the array.  So we fail if that time hasn't passed.
6777                  * For a reshape that keeps the number of devices the same
6778                  * mdadm must be monitoring the reshape can keeping the
6779                  * critical areas read-only and backed up.  It will start
6780                  * the array in read-only mode, so we check for that.
6781                  */
6782                 sector_t here_new, here_old;
6783                 int old_disks;
6784                 int max_degraded = (mddev->level == 6 ? 2 : 1);
6785                 int chunk_sectors;
6786                 int new_data_disks;
6787
6788                 if (journal_dev) {
6789                         printk(KERN_ERR "md/raid:%s: don't support reshape with journal - aborting.\n",
6790                                mdname(mddev));
6791                         return -EINVAL;
6792                 }
6793
6794                 if (mddev->new_level != mddev->level) {
6795                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
6796                                "required - aborting.\n",
6797                                mdname(mddev));
6798                         return -EINVAL;
6799                 }
6800                 old_disks = mddev->raid_disks - mddev->delta_disks;
6801                 /* reshape_position must be on a new-stripe boundary, and one
6802                  * further up in new geometry must map after here in old
6803                  * geometry.
6804                  * If the chunk sizes are different, then as we perform reshape
6805                  * in units of the largest of the two, reshape_position needs
6806                  * be a multiple of the largest chunk size times new data disks.
6807                  */
6808                 here_new = mddev->reshape_position;
6809                 chunk_sectors = max(mddev->chunk_sectors, mddev->new_chunk_sectors);
6810                 new_data_disks = mddev->raid_disks - max_degraded;
6811                 if (sector_div(here_new, chunk_sectors * new_data_disks)) {
6812                         printk(KERN_ERR "md/raid:%s: reshape_position not "
6813                                "on a stripe boundary\n", mdname(mddev));
6814                         return -EINVAL;
6815                 }
6816                 reshape_offset = here_new * chunk_sectors;
6817                 /* here_new is the stripe we will write to */
6818                 here_old = mddev->reshape_position;
6819                 sector_div(here_old, chunk_sectors * (old_disks-max_degraded));
6820                 /* here_old is the first stripe that we might need to read
6821                  * from */
6822                 if (mddev->delta_disks == 0) {
6823                         /* We cannot be sure it is safe to start an in-place
6824                          * reshape.  It is only safe if user-space is monitoring
6825                          * and taking constant backups.
6826                          * mdadm always starts a situation like this in
6827                          * readonly mode so it can take control before
6828                          * allowing any writes.  So just check for that.
6829                          */
6830                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6831                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
6832                                 /* not really in-place - so OK */;
6833                         else if (mddev->ro == 0) {
6834                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
6835                                        "must be started in read-only mode "
6836                                        "- aborting\n",
6837                                        mdname(mddev));
6838                                 return -EINVAL;
6839                         }
6840                 } else if (mddev->reshape_backwards
6841                     ? (here_new * chunk_sectors + min_offset_diff <=
6842                        here_old * chunk_sectors)
6843                     : (here_new * chunk_sectors >=
6844                        here_old * chunk_sectors + (-min_offset_diff))) {
6845                         /* Reading from the same stripe as writing to - bad */
6846                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
6847                                "auto-recovery - aborting.\n",
6848                                mdname(mddev));
6849                         return -EINVAL;
6850                 }
6851                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
6852                        mdname(mddev));
6853                 /* OK, we should be able to continue; */
6854         } else {
6855                 BUG_ON(mddev->level != mddev->new_level);
6856                 BUG_ON(mddev->layout != mddev->new_layout);
6857                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6858                 BUG_ON(mddev->delta_disks != 0);
6859         }
6860
6861         if (mddev->private == NULL)
6862                 conf = setup_conf(mddev);
6863         else
6864                 conf = mddev->private;
6865
6866         if (IS_ERR(conf))
6867                 return PTR_ERR(conf);
6868
6869         if (test_bit(MD_HAS_JOURNAL, &mddev->flags) && !journal_dev) {
6870                 printk(KERN_ERR "md/raid:%s: journal disk is missing, force array readonly\n",
6871                        mdname(mddev));
6872                 mddev->ro = 1;
6873                 set_disk_ro(mddev->gendisk, 1);
6874         }
6875
6876         conf->min_offset_diff = min_offset_diff;
6877         mddev->thread = conf->thread;
6878         conf->thread = NULL;
6879         mddev->private = conf;
6880
6881         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6882              i++) {
6883                 rdev = conf->disks[i].rdev;
6884                 if (!rdev && conf->disks[i].replacement) {
6885                         /* The replacement is all we have yet */
6886                         rdev = conf->disks[i].replacement;
6887                         conf->disks[i].replacement = NULL;
6888                         clear_bit(Replacement, &rdev->flags);
6889                         conf->disks[i].rdev = rdev;
6890                 }
6891                 if (!rdev)
6892                         continue;
6893                 if (conf->disks[i].replacement &&
6894                     conf->reshape_progress != MaxSector) {
6895                         /* replacements and reshape simply do not mix. */
6896                         printk(KERN_ERR "md: cannot handle concurrent "
6897                                "replacement and reshape.\n");
6898                         goto abort;
6899                 }
6900                 if (test_bit(In_sync, &rdev->flags)) {
6901                         working_disks++;
6902                         continue;
6903                 }
6904                 /* This disc is not fully in-sync.  However if it
6905                  * just stored parity (beyond the recovery_offset),
6906                  * when we don't need to be concerned about the
6907                  * array being dirty.
6908                  * When reshape goes 'backwards', we never have
6909                  * partially completed devices, so we only need
6910                  * to worry about reshape going forwards.
6911                  */
6912                 /* Hack because v0.91 doesn't store recovery_offset properly. */
6913                 if (mddev->major_version == 0 &&
6914                     mddev->minor_version > 90)
6915                         rdev->recovery_offset = reshape_offset;
6916
6917                 if (rdev->recovery_offset < reshape_offset) {
6918                         /* We need to check old and new layout */
6919                         if (!only_parity(rdev->raid_disk,
6920                                          conf->algorithm,
6921                                          conf->raid_disks,
6922                                          conf->max_degraded))
6923                                 continue;
6924                 }
6925                 if (!only_parity(rdev->raid_disk,
6926                                  conf->prev_algo,
6927                                  conf->previous_raid_disks,
6928                                  conf->max_degraded))
6929                         continue;
6930                 dirty_parity_disks++;
6931         }
6932
6933         /*
6934          * 0 for a fully functional array, 1 or 2 for a degraded array.
6935          */
6936         mddev->degraded = calc_degraded(conf);
6937
6938         if (has_failed(conf)) {
6939                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
6940                         " (%d/%d failed)\n",
6941                         mdname(mddev), mddev->degraded, conf->raid_disks);
6942                 goto abort;
6943         }
6944
6945         /* device size must be a multiple of chunk size */
6946         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
6947         mddev->resync_max_sectors = mddev->dev_sectors;
6948
6949         if (mddev->degraded > dirty_parity_disks &&
6950             mddev->recovery_cp != MaxSector) {
6951                 if (mddev->ok_start_degraded)
6952                         printk(KERN_WARNING
6953                                "md/raid:%s: starting dirty degraded array"
6954                                " - data corruption possible.\n",
6955                                mdname(mddev));
6956                 else {
6957                         printk(KERN_ERR
6958                                "md/raid:%s: cannot start dirty degraded array.\n",
6959                                mdname(mddev));
6960                         goto abort;
6961                 }
6962         }
6963
6964         if (mddev->degraded == 0)
6965                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
6966                        " devices, algorithm %d\n", mdname(mddev), conf->level,
6967                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
6968                        mddev->new_layout);
6969         else
6970                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
6971                        " out of %d devices, algorithm %d\n",
6972                        mdname(mddev), conf->level,
6973                        mddev->raid_disks - mddev->degraded,
6974                        mddev->raid_disks, mddev->new_layout);
6975
6976         print_raid5_conf(conf);
6977
6978         if (conf->reshape_progress != MaxSector) {
6979                 conf->reshape_safe = conf->reshape_progress;
6980                 atomic_set(&conf->reshape_stripes, 0);
6981                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6982                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6983                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6984                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6985                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6986                                                         "reshape");
6987                 if (!mddev->sync_thread)
6988                         goto abort;
6989         }
6990
6991         /* Ok, everything is just fine now */
6992         if (mddev->to_remove == &raid5_attrs_group)
6993                 mddev->to_remove = NULL;
6994         else if (mddev->kobj.sd &&
6995             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
6996                 printk(KERN_WARNING
6997                        "raid5: failed to create sysfs attributes for %s\n",
6998                        mdname(mddev));
6999         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7000
7001         if (mddev->queue) {
7002                 int chunk_size;
7003                 bool discard_supported = true;
7004                 /* read-ahead size must cover two whole stripes, which
7005                  * is 2 * (datadisks) * chunksize where 'n' is the
7006                  * number of raid devices
7007                  */
7008                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
7009                 int stripe = data_disks *
7010                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
7011                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7012                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7013
7014                 chunk_size = mddev->chunk_sectors << 9;
7015                 blk_queue_io_min(mddev->queue, chunk_size);
7016                 blk_queue_io_opt(mddev->queue, chunk_size *
7017                                  (conf->raid_disks - conf->max_degraded));
7018                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
7019                 /*
7020                  * We can only discard a whole stripe. It doesn't make sense to
7021                  * discard data disk but write parity disk
7022                  */
7023                 stripe = stripe * PAGE_SIZE;
7024                 /* Round up to power of 2, as discard handling
7025                  * currently assumes that */
7026                 while ((stripe-1) & stripe)
7027                         stripe = (stripe | (stripe-1)) + 1;
7028                 mddev->queue->limits.discard_alignment = stripe;
7029                 mddev->queue->limits.discard_granularity = stripe;
7030
7031                 /*
7032                  * We use 16-bit counter of active stripes in bi_phys_segments
7033                  * (minus one for over-loaded initialization)
7034                  */
7035                 blk_queue_max_hw_sectors(mddev->queue, 0xfffe * STRIPE_SECTORS);
7036                 blk_queue_max_discard_sectors(mddev->queue,
7037                                               0xfffe * STRIPE_SECTORS);
7038
7039                 /*
7040                  * unaligned part of discard request will be ignored, so can't
7041                  * guarantee discard_zeroes_data
7042                  */
7043                 mddev->queue->limits.discard_zeroes_data = 0;
7044
7045                 blk_queue_max_write_same_sectors(mddev->queue, 0);
7046
7047                 rdev_for_each(rdev, mddev) {
7048                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7049                                           rdev->data_offset << 9);
7050                         disk_stack_limits(mddev->gendisk, rdev->bdev,
7051                                           rdev->new_data_offset << 9);
7052                         /*
7053                          * discard_zeroes_data is required, otherwise data
7054                          * could be lost. Consider a scenario: discard a stripe
7055                          * (the stripe could be inconsistent if
7056                          * discard_zeroes_data is 0); write one disk of the
7057                          * stripe (the stripe could be inconsistent again
7058                          * depending on which disks are used to calculate
7059                          * parity); the disk is broken; The stripe data of this
7060                          * disk is lost.
7061                          */
7062                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
7063                             !bdev_get_queue(rdev->bdev)->
7064                                                 limits.discard_zeroes_data)
7065                                 discard_supported = false;
7066                         /* Unfortunately, discard_zeroes_data is not currently
7067                          * a guarantee - just a hint.  So we only allow DISCARD
7068                          * if the sysadmin has confirmed that only safe devices
7069                          * are in use by setting a module parameter.
7070                          */
7071                         if (!devices_handle_discard_safely) {
7072                                 if (discard_supported) {
7073                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
7074                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
7075                                 }
7076                                 discard_supported = false;
7077                         }
7078                 }
7079
7080                 if (discard_supported &&
7081                     mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
7082                     mddev->queue->limits.discard_granularity >= stripe)
7083                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
7084                                                 mddev->queue);
7085                 else
7086                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
7087                                                 mddev->queue);
7088         }
7089
7090         if (journal_dev) {
7091                 char b[BDEVNAME_SIZE];
7092
7093                 printk(KERN_INFO"md/raid:%s: using device %s as journal\n",
7094                        mdname(mddev), bdevname(journal_dev->bdev, b));
7095                 r5l_init_log(conf, journal_dev);
7096         }
7097
7098         return 0;
7099 abort:
7100         md_unregister_thread(&mddev->thread);
7101         print_raid5_conf(conf);
7102         free_conf(conf);
7103         mddev->private = NULL;
7104         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
7105         return -EIO;
7106 }
7107
7108 static void raid5_free(struct mddev *mddev, void *priv)
7109 {
7110         struct r5conf *conf = priv;
7111
7112         free_conf(conf);
7113         mddev->to_remove = &raid5_attrs_group;
7114 }
7115
7116 static void status(struct seq_file *seq, struct mddev *mddev)
7117 {
7118         struct r5conf *conf = mddev->private;
7119         int i;
7120
7121         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
7122                 conf->chunk_sectors / 2, mddev->layout);
7123         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
7124         for (i = 0; i < conf->raid_disks; i++)
7125                 seq_printf (seq, "%s",
7126                                conf->disks[i].rdev &&
7127                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
7128         seq_printf (seq, "]");
7129 }
7130
7131 static void print_raid5_conf (struct r5conf *conf)
7132 {
7133         int i;
7134         struct disk_info *tmp;
7135
7136         printk(KERN_DEBUG "RAID conf printout:\n");
7137         if (!conf) {
7138                 printk("(conf==NULL)\n");
7139                 return;
7140         }
7141         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
7142                conf->raid_disks,
7143                conf->raid_disks - conf->mddev->degraded);
7144
7145         for (i = 0; i < conf->raid_disks; i++) {
7146                 char b[BDEVNAME_SIZE];
7147                 tmp = conf->disks + i;
7148                 if (tmp->rdev)
7149                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
7150                                i, !test_bit(Faulty, &tmp->rdev->flags),
7151                                bdevname(tmp->rdev->bdev, b));
7152         }
7153 }
7154
7155 static int raid5_spare_active(struct mddev *mddev)
7156 {
7157         int i;
7158         struct r5conf *conf = mddev->private;
7159         struct disk_info *tmp;
7160         int count = 0;
7161         unsigned long flags;
7162
7163         for (i = 0; i < conf->raid_disks; i++) {
7164                 tmp = conf->disks + i;
7165                 if (tmp->replacement
7166                     && tmp->replacement->recovery_offset == MaxSector
7167                     && !test_bit(Faulty, &tmp->replacement->flags)
7168                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
7169                         /* Replacement has just become active. */
7170                         if (!tmp->rdev
7171                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
7172                                 count++;
7173                         if (tmp->rdev) {
7174                                 /* Replaced device not technically faulty,
7175                                  * but we need to be sure it gets removed
7176                                  * and never re-added.
7177                                  */
7178                                 set_bit(Faulty, &tmp->rdev->flags);
7179                                 sysfs_notify_dirent_safe(
7180                                         tmp->rdev->sysfs_state);
7181                         }
7182                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
7183                 } else if (tmp->rdev
7184                     && tmp->rdev->recovery_offset == MaxSector
7185                     && !test_bit(Faulty, &tmp->rdev->flags)
7186                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
7187                         count++;
7188                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
7189                 }
7190         }
7191         spin_lock_irqsave(&conf->device_lock, flags);
7192         mddev->degraded = calc_degraded(conf);
7193         spin_unlock_irqrestore(&conf->device_lock, flags);
7194         print_raid5_conf(conf);
7195         return count;
7196 }
7197
7198 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
7199 {
7200         struct r5conf *conf = mddev->private;
7201         int err = 0;
7202         int number = rdev->raid_disk;
7203         struct md_rdev **rdevp;
7204         struct disk_info *p = conf->disks + number;
7205
7206         print_raid5_conf(conf);
7207         if (test_bit(Journal, &rdev->flags)) {
7208                 /*
7209                  * journal disk is not removable, but we need give a chance to
7210                  * update superblock of other disks. Otherwise journal disk
7211                  * will be considered as 'fresh'
7212                  */
7213                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
7214                 return -EINVAL;
7215         }
7216         if (rdev == p->rdev)
7217                 rdevp = &p->rdev;
7218         else if (rdev == p->replacement)
7219                 rdevp = &p->replacement;
7220         else
7221                 return 0;
7222
7223         if (number >= conf->raid_disks &&
7224             conf->reshape_progress == MaxSector)
7225                 clear_bit(In_sync, &rdev->flags);
7226
7227         if (test_bit(In_sync, &rdev->flags) ||
7228             atomic_read(&rdev->nr_pending)) {
7229                 err = -EBUSY;
7230                 goto abort;
7231         }
7232         /* Only remove non-faulty devices if recovery
7233          * isn't possible.
7234          */
7235         if (!test_bit(Faulty, &rdev->flags) &&
7236             mddev->recovery_disabled != conf->recovery_disabled &&
7237             !has_failed(conf) &&
7238             (!p->replacement || p->replacement == rdev) &&
7239             number < conf->raid_disks) {
7240                 err = -EBUSY;
7241                 goto abort;
7242         }
7243         *rdevp = NULL;
7244         synchronize_rcu();
7245         if (atomic_read(&rdev->nr_pending)) {
7246                 /* lost the race, try later */
7247                 err = -EBUSY;
7248                 *rdevp = rdev;
7249         } else if (p->replacement) {
7250                 /* We must have just cleared 'rdev' */
7251                 p->rdev = p->replacement;
7252                 clear_bit(Replacement, &p->replacement->flags);
7253                 smp_mb(); /* Make sure other CPUs may see both as identical
7254                            * but will never see neither - if they are careful
7255                            */
7256                 p->replacement = NULL;
7257                 clear_bit(WantReplacement, &rdev->flags);
7258         } else
7259                 /* We might have just removed the Replacement as faulty-
7260                  * clear the bit just in case
7261                  */
7262                 clear_bit(WantReplacement, &rdev->flags);
7263 abort:
7264
7265         print_raid5_conf(conf);
7266         return err;
7267 }
7268
7269 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
7270 {
7271         struct r5conf *conf = mddev->private;
7272         int err = -EEXIST;
7273         int disk;
7274         struct disk_info *p;
7275         int first = 0;
7276         int last = conf->raid_disks - 1;
7277
7278         if (test_bit(Journal, &rdev->flags))
7279                 return -EINVAL;
7280         if (mddev->recovery_disabled == conf->recovery_disabled)
7281                 return -EBUSY;
7282
7283         if (rdev->saved_raid_disk < 0 && has_failed(conf))
7284                 /* no point adding a device */
7285                 return -EINVAL;
7286
7287         if (rdev->raid_disk >= 0)
7288                 first = last = rdev->raid_disk;
7289
7290         /*
7291          * find the disk ... but prefer rdev->saved_raid_disk
7292          * if possible.
7293          */
7294         if (rdev->saved_raid_disk >= 0 &&
7295             rdev->saved_raid_disk >= first &&
7296             conf->disks[rdev->saved_raid_disk].rdev == NULL)
7297                 first = rdev->saved_raid_disk;
7298
7299         for (disk = first; disk <= last; disk++) {
7300                 p = conf->disks + disk;
7301                 if (p->rdev == NULL) {
7302                         clear_bit(In_sync, &rdev->flags);
7303                         rdev->raid_disk = disk;
7304                         err = 0;
7305                         if (rdev->saved_raid_disk != disk)
7306                                 conf->fullsync = 1;
7307                         rcu_assign_pointer(p->rdev, rdev);
7308                         goto out;
7309                 }
7310         }
7311         for (disk = first; disk <= last; disk++) {
7312                 p = conf->disks + disk;
7313                 if (test_bit(WantReplacement, &p->rdev->flags) &&
7314                     p->replacement == NULL) {
7315                         clear_bit(In_sync, &rdev->flags);
7316                         set_bit(Replacement, &rdev->flags);
7317                         rdev->raid_disk = disk;
7318                         err = 0;
7319                         conf->fullsync = 1;
7320                         rcu_assign_pointer(p->replacement, rdev);
7321                         break;
7322                 }
7323         }
7324 out:
7325         print_raid5_conf(conf);
7326         return err;
7327 }
7328
7329 static int raid5_resize(struct mddev *mddev, sector_t sectors)
7330 {
7331         /* no resync is happening, and there is enough space
7332          * on all devices, so we can resize.
7333          * We need to make sure resync covers any new space.
7334          * If the array is shrinking we should possibly wait until
7335          * any io in the removed space completes, but it hardly seems
7336          * worth it.
7337          */
7338         sector_t newsize;
7339         struct r5conf *conf = mddev->private;
7340
7341         if (conf->log)
7342                 return -EINVAL;
7343         sectors &= ~((sector_t)conf->chunk_sectors - 1);
7344         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
7345         if (mddev->external_size &&
7346             mddev->array_sectors > newsize)
7347                 return -EINVAL;
7348         if (mddev->bitmap) {
7349                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
7350                 if (ret)
7351                         return ret;
7352         }
7353         md_set_array_sectors(mddev, newsize);
7354         set_capacity(mddev->gendisk, mddev->array_sectors);
7355         revalidate_disk(mddev->gendisk);
7356         if (sectors > mddev->dev_sectors &&
7357             mddev->recovery_cp > mddev->dev_sectors) {
7358                 mddev->recovery_cp = mddev->dev_sectors;
7359                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
7360         }
7361         mddev->dev_sectors = sectors;
7362         mddev->resync_max_sectors = sectors;
7363         return 0;
7364 }
7365
7366 static int check_stripe_cache(struct mddev *mddev)
7367 {
7368         /* Can only proceed if there are plenty of stripe_heads.
7369          * We need a minimum of one full stripe,, and for sensible progress
7370          * it is best to have about 4 times that.
7371          * If we require 4 times, then the default 256 4K stripe_heads will
7372          * allow for chunk sizes up to 256K, which is probably OK.
7373          * If the chunk size is greater, user-space should request more
7374          * stripe_heads first.
7375          */
7376         struct r5conf *conf = mddev->private;
7377         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
7378             > conf->min_nr_stripes ||
7379             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
7380             > conf->min_nr_stripes) {
7381                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
7382                        mdname(mddev),
7383                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
7384                         / STRIPE_SIZE)*4);
7385                 return 0;
7386         }
7387         return 1;
7388 }
7389
7390 static int check_reshape(struct mddev *mddev)
7391 {
7392         struct r5conf *conf = mddev->private;
7393
7394         if (conf->log)
7395                 return -EINVAL;
7396         if (mddev->delta_disks == 0 &&
7397             mddev->new_layout == mddev->layout &&
7398             mddev->new_chunk_sectors == mddev->chunk_sectors)
7399                 return 0; /* nothing to do */
7400         if (has_failed(conf))
7401                 return -EINVAL;
7402         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
7403                 /* We might be able to shrink, but the devices must
7404                  * be made bigger first.
7405                  * For raid6, 4 is the minimum size.
7406                  * Otherwise 2 is the minimum
7407                  */
7408                 int min = 2;
7409                 if (mddev->level == 6)
7410                         min = 4;
7411                 if (mddev->raid_disks + mddev->delta_disks < min)
7412                         return -EINVAL;
7413         }
7414
7415         if (!check_stripe_cache(mddev))
7416                 return -ENOSPC;
7417
7418         if (mddev->new_chunk_sectors > mddev->chunk_sectors ||
7419             mddev->delta_disks > 0)
7420                 if (resize_chunks(conf,
7421                                   conf->previous_raid_disks
7422                                   + max(0, mddev->delta_disks),
7423                                   max(mddev->new_chunk_sectors,
7424                                       mddev->chunk_sectors)
7425                             ) < 0)
7426                         return -ENOMEM;
7427         return resize_stripes(conf, (conf->previous_raid_disks
7428                                      + mddev->delta_disks));
7429 }
7430
7431 static int raid5_start_reshape(struct mddev *mddev)
7432 {
7433         struct r5conf *conf = mddev->private;
7434         struct md_rdev *rdev;
7435         int spares = 0;
7436         unsigned long flags;
7437
7438         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
7439                 return -EBUSY;
7440
7441         if (!check_stripe_cache(mddev))
7442                 return -ENOSPC;
7443
7444         if (has_failed(conf))
7445                 return -EINVAL;
7446
7447         rdev_for_each(rdev, mddev) {
7448                 if (!test_bit(In_sync, &rdev->flags)
7449                     && !test_bit(Faulty, &rdev->flags))
7450                         spares++;
7451         }
7452
7453         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
7454                 /* Not enough devices even to make a degraded array
7455                  * of that size
7456                  */
7457                 return -EINVAL;
7458
7459         /* Refuse to reduce size of the array.  Any reductions in
7460          * array size must be through explicit setting of array_size
7461          * attribute.
7462          */
7463         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
7464             < mddev->array_sectors) {
7465                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
7466                        "before number of disks\n", mdname(mddev));
7467                 return -EINVAL;
7468         }
7469
7470         atomic_set(&conf->reshape_stripes, 0);
7471         spin_lock_irq(&conf->device_lock);
7472         write_seqcount_begin(&conf->gen_lock);
7473         conf->previous_raid_disks = conf->raid_disks;
7474         conf->raid_disks += mddev->delta_disks;
7475         conf->prev_chunk_sectors = conf->chunk_sectors;
7476         conf->chunk_sectors = mddev->new_chunk_sectors;
7477         conf->prev_algo = conf->algorithm;
7478         conf->algorithm = mddev->new_layout;
7479         conf->generation++;
7480         /* Code that selects data_offset needs to see the generation update
7481          * if reshape_progress has been set - so a memory barrier needed.
7482          */
7483         smp_mb();
7484         if (mddev->reshape_backwards)
7485                 conf->reshape_progress = raid5_size(mddev, 0, 0);
7486         else
7487                 conf->reshape_progress = 0;
7488         conf->reshape_safe = conf->reshape_progress;
7489         write_seqcount_end(&conf->gen_lock);
7490         spin_unlock_irq(&conf->device_lock);
7491
7492         /* Now make sure any requests that proceeded on the assumption
7493          * the reshape wasn't running - like Discard or Read - have
7494          * completed.
7495          */
7496         mddev_suspend(mddev);
7497         mddev_resume(mddev);
7498
7499         /* Add some new drives, as many as will fit.
7500          * We know there are enough to make the newly sized array work.
7501          * Don't add devices if we are reducing the number of
7502          * devices in the array.  This is because it is not possible
7503          * to correctly record the "partially reconstructed" state of
7504          * such devices during the reshape and confusion could result.
7505          */
7506         if (mddev->delta_disks >= 0) {
7507                 rdev_for_each(rdev, mddev)
7508                         if (rdev->raid_disk < 0 &&
7509                             !test_bit(Faulty, &rdev->flags)) {
7510                                 if (raid5_add_disk(mddev, rdev) == 0) {
7511                                         if (rdev->raid_disk
7512                                             >= conf->previous_raid_disks)
7513                                                 set_bit(In_sync, &rdev->flags);
7514                                         else
7515                                                 rdev->recovery_offset = 0;
7516
7517                                         if (sysfs_link_rdev(mddev, rdev))
7518                                                 /* Failure here is OK */;
7519                                 }
7520                         } else if (rdev->raid_disk >= conf->previous_raid_disks
7521                                    && !test_bit(Faulty, &rdev->flags)) {
7522                                 /* This is a spare that was manually added */
7523                                 set_bit(In_sync, &rdev->flags);
7524                         }
7525
7526                 /* When a reshape changes the number of devices,
7527                  * ->degraded is measured against the larger of the
7528                  * pre and post number of devices.
7529                  */
7530                 spin_lock_irqsave(&conf->device_lock, flags);
7531                 mddev->degraded = calc_degraded(conf);
7532                 spin_unlock_irqrestore(&conf->device_lock, flags);
7533         }
7534         mddev->raid_disks = conf->raid_disks;
7535         mddev->reshape_position = conf->reshape_progress;
7536         set_bit(MD_CHANGE_DEVS, &mddev->flags);
7537
7538         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
7539         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
7540         clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
7541         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
7542         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
7543         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
7544                                                 "reshape");
7545         if (!mddev->sync_thread) {
7546                 mddev->recovery = 0;
7547                 spin_lock_irq(&conf->device_lock);
7548                 write_seqcount_begin(&conf->gen_lock);
7549                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
7550                 mddev->new_chunk_sectors =
7551                         conf->chunk_sectors = conf->prev_chunk_sectors;
7552                 mddev->new_layout = conf->algorithm = conf->prev_algo;
7553                 rdev_for_each(rdev, mddev)
7554                         rdev->new_data_offset = rdev->data_offset;
7555                 smp_wmb();
7556                 conf->generation --;
7557                 conf->reshape_progress = MaxSector;
7558                 mddev->reshape_position = MaxSector;
7559                 write_seqcount_end(&conf->gen_lock);
7560                 spin_unlock_irq(&conf->device_lock);
7561                 return -EAGAIN;
7562         }
7563         conf->reshape_checkpoint = jiffies;
7564         md_wakeup_thread(mddev->sync_thread);
7565         md_new_event(mddev);
7566         return 0;
7567 }
7568
7569 /* This is called from the reshape thread and should make any
7570  * changes needed in 'conf'
7571  */
7572 static void end_reshape(struct r5conf *conf)
7573 {
7574
7575         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
7576
7577                 spin_lock_irq(&conf->device_lock);
7578                 conf->previous_raid_disks = conf->raid_disks;
7579                 md_finish_reshape(conf->mddev);
7580                 smp_wmb();
7581                 conf->reshape_progress = MaxSector;
7582                 conf->mddev->reshape_position = MaxSector;
7583                 spin_unlock_irq(&conf->device_lock);
7584                 wake_up(&conf->wait_for_overlap);
7585
7586                 /* read-ahead size must cover two whole stripes, which is
7587                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
7588                  */
7589                 if (conf->mddev->queue) {
7590                         int data_disks = conf->raid_disks - conf->max_degraded;
7591                         int stripe = data_disks * ((conf->chunk_sectors << 9)
7592                                                    / PAGE_SIZE);
7593                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
7594                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
7595                 }
7596         }
7597 }
7598
7599 /* This is called from the raid5d thread with mddev_lock held.
7600  * It makes config changes to the device.
7601  */
7602 static void raid5_finish_reshape(struct mddev *mddev)
7603 {
7604         struct r5conf *conf = mddev->private;
7605
7606         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
7607
7608                 if (mddev->delta_disks > 0) {
7609                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
7610                         set_capacity(mddev->gendisk, mddev->array_sectors);
7611                         revalidate_disk(mddev->gendisk);
7612                 } else {
7613                         int d;
7614                         spin_lock_irq(&conf->device_lock);
7615                         mddev->degraded = calc_degraded(conf);
7616                         spin_unlock_irq(&conf->device_lock);
7617                         for (d = conf->raid_disks ;
7618                              d < conf->raid_disks - mddev->delta_disks;
7619                              d++) {
7620                                 struct md_rdev *rdev = conf->disks[d].rdev;
7621                                 if (rdev)
7622                                         clear_bit(In_sync, &rdev->flags);
7623                                 rdev = conf->disks[d].replacement;
7624                                 if (rdev)
7625                                         clear_bit(In_sync, &rdev->flags);
7626                         }
7627                 }
7628                 mddev->layout = conf->algorithm;
7629                 mddev->chunk_sectors = conf->chunk_sectors;
7630                 mddev->reshape_position = MaxSector;
7631                 mddev->delta_disks = 0;
7632                 mddev->reshape_backwards = 0;
7633         }
7634 }
7635
7636 static void raid5_quiesce(struct mddev *mddev, int state)
7637 {
7638         struct r5conf *conf = mddev->private;
7639
7640         switch(state) {
7641         case 2: /* resume for a suspend */
7642                 wake_up(&conf->wait_for_overlap);
7643                 break;
7644
7645         case 1: /* stop all writes */
7646                 lock_all_device_hash_locks_irq(conf);
7647                 /* '2' tells resync/reshape to pause so that all
7648                  * active stripes can drain
7649                  */
7650                 conf->quiesce = 2;
7651                 wait_event_cmd(conf->wait_for_quiescent,
7652                                     atomic_read(&conf->active_stripes) == 0 &&
7653                                     atomic_read(&conf->active_aligned_reads) == 0,
7654                                     unlock_all_device_hash_locks_irq(conf),
7655                                     lock_all_device_hash_locks_irq(conf));
7656                 conf->quiesce = 1;
7657                 unlock_all_device_hash_locks_irq(conf);
7658                 /* allow reshape to continue */
7659                 wake_up(&conf->wait_for_overlap);
7660                 break;
7661
7662         case 0: /* re-enable writes */
7663                 lock_all_device_hash_locks_irq(conf);
7664                 conf->quiesce = 0;
7665                 wake_up(&conf->wait_for_quiescent);
7666                 wake_up(&conf->wait_for_overlap);
7667                 unlock_all_device_hash_locks_irq(conf);
7668                 break;
7669         }
7670         r5l_quiesce(conf->log, state);
7671 }
7672
7673 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
7674 {
7675         struct r0conf *raid0_conf = mddev->private;
7676         sector_t sectors;
7677
7678         /* for raid0 takeover only one zone is supported */
7679         if (raid0_conf->nr_strip_zones > 1) {
7680                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
7681                        mdname(mddev));
7682                 return ERR_PTR(-EINVAL);
7683         }
7684
7685         sectors = raid0_conf->strip_zone[0].zone_end;
7686         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
7687         mddev->dev_sectors = sectors;
7688         mddev->new_level = level;
7689         mddev->new_layout = ALGORITHM_PARITY_N;
7690         mddev->new_chunk_sectors = mddev->chunk_sectors;
7691         mddev->raid_disks += 1;
7692         mddev->delta_disks = 1;
7693         /* make sure it will be not marked as dirty */
7694         mddev->recovery_cp = MaxSector;
7695
7696         return setup_conf(mddev);
7697 }
7698
7699 static void *raid5_takeover_raid1(struct mddev *mddev)
7700 {
7701         int chunksect;
7702
7703         if (mddev->raid_disks != 2 ||
7704             mddev->degraded > 1)
7705                 return ERR_PTR(-EINVAL);
7706
7707         /* Should check if there are write-behind devices? */
7708
7709         chunksect = 64*2; /* 64K by default */
7710
7711         /* The array must be an exact multiple of chunksize */
7712         while (chunksect && (mddev->array_sectors & (chunksect-1)))
7713                 chunksect >>= 1;
7714
7715         if ((chunksect<<9) < STRIPE_SIZE)
7716                 /* array size does not allow a suitable chunk size */
7717                 return ERR_PTR(-EINVAL);
7718
7719         mddev->new_level = 5;
7720         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
7721         mddev->new_chunk_sectors = chunksect;
7722
7723         return setup_conf(mddev);
7724 }
7725
7726 static void *raid5_takeover_raid6(struct mddev *mddev)
7727 {
7728         int new_layout;
7729
7730         switch (mddev->layout) {
7731         case ALGORITHM_LEFT_ASYMMETRIC_6:
7732                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
7733                 break;
7734         case ALGORITHM_RIGHT_ASYMMETRIC_6:
7735                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
7736                 break;
7737         case ALGORITHM_LEFT_SYMMETRIC_6:
7738                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
7739                 break;
7740         case ALGORITHM_RIGHT_SYMMETRIC_6:
7741                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
7742                 break;
7743         case ALGORITHM_PARITY_0_6:
7744                 new_layout = ALGORITHM_PARITY_0;
7745                 break;
7746         case ALGORITHM_PARITY_N:
7747                 new_layout = ALGORITHM_PARITY_N;
7748                 break;
7749         default:
7750                 return ERR_PTR(-EINVAL);
7751         }
7752         mddev->new_level = 5;
7753         mddev->new_layout = new_layout;
7754         mddev->delta_disks = -1;
7755         mddev->raid_disks -= 1;
7756         return setup_conf(mddev);
7757 }
7758
7759 static int raid5_check_reshape(struct mddev *mddev)
7760 {
7761         /* For a 2-drive array, the layout and chunk size can be changed
7762          * immediately as not restriping is needed.
7763          * For larger arrays we record the new value - after validation
7764          * to be used by a reshape pass.
7765          */
7766         struct r5conf *conf = mddev->private;
7767         int new_chunk = mddev->new_chunk_sectors;
7768
7769         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
7770                 return -EINVAL;
7771         if (new_chunk > 0) {
7772                 if (!is_power_of_2(new_chunk))
7773                         return -EINVAL;
7774                 if (new_chunk < (PAGE_SIZE>>9))
7775                         return -EINVAL;
7776                 if (mddev->array_sectors & (new_chunk-1))
7777                         /* not factor of array size */
7778                         return -EINVAL;
7779         }
7780
7781         /* They look valid */
7782
7783         if (mddev->raid_disks == 2) {
7784                 /* can make the change immediately */
7785                 if (mddev->new_layout >= 0) {
7786                         conf->algorithm = mddev->new_layout;
7787                         mddev->layout = mddev->new_layout;
7788                 }
7789                 if (new_chunk > 0) {
7790                         conf->chunk_sectors = new_chunk ;
7791                         mddev->chunk_sectors = new_chunk;
7792                 }
7793                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
7794                 md_wakeup_thread(mddev->thread);
7795         }
7796         return check_reshape(mddev);
7797 }
7798
7799 static int raid6_check_reshape(struct mddev *mddev)
7800 {
7801         int new_chunk = mddev->new_chunk_sectors;
7802
7803         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
7804                 return -EINVAL;
7805         if (new_chunk > 0) {
7806                 if (!is_power_of_2(new_chunk))
7807                         return -EINVAL;
7808                 if (new_chunk < (PAGE_SIZE >> 9))
7809                         return -EINVAL;
7810                 if (mddev->array_sectors & (new_chunk-1))
7811                         /* not factor of array size */
7812                         return -EINVAL;
7813         }
7814
7815         /* They look valid */
7816         return check_reshape(mddev);
7817 }
7818
7819 static void *raid5_takeover(struct mddev *mddev)
7820 {
7821         /* raid5 can take over:
7822          *  raid0 - if there is only one strip zone - make it a raid4 layout
7823          *  raid1 - if there are two drives.  We need to know the chunk size
7824          *  raid4 - trivial - just use a raid4 layout.
7825          *  raid6 - Providing it is a *_6 layout
7826          */
7827         if (mddev->level == 0)
7828                 return raid45_takeover_raid0(mddev, 5);
7829         if (mddev->level == 1)
7830                 return raid5_takeover_raid1(mddev);
7831         if (mddev->level == 4) {
7832                 mddev->new_layout = ALGORITHM_PARITY_N;
7833                 mddev->new_level = 5;
7834                 return setup_conf(mddev);
7835         }
7836         if (mddev->level == 6)
7837                 return raid5_takeover_raid6(mddev);
7838
7839         return ERR_PTR(-EINVAL);
7840 }
7841
7842 static void *raid4_takeover(struct mddev *mddev)
7843 {
7844         /* raid4 can take over:
7845          *  raid0 - if there is only one strip zone
7846          *  raid5 - if layout is right
7847          */
7848         if (mddev->level == 0)
7849                 return raid45_takeover_raid0(mddev, 4);
7850         if (mddev->level == 5 &&
7851             mddev->layout == ALGORITHM_PARITY_N) {
7852                 mddev->new_layout = 0;
7853                 mddev->new_level = 4;
7854                 return setup_conf(mddev);
7855         }
7856         return ERR_PTR(-EINVAL);
7857 }
7858
7859 static struct md_personality raid5_personality;
7860
7861 static void *raid6_takeover(struct mddev *mddev)
7862 {
7863         /* Currently can only take over a raid5.  We map the
7864          * personality to an equivalent raid6 personality
7865          * with the Q block at the end.
7866          */
7867         int new_layout;
7868
7869         if (mddev->pers != &raid5_personality)
7870                 return ERR_PTR(-EINVAL);
7871         if (mddev->degraded > 1)
7872                 return ERR_PTR(-EINVAL);
7873         if (mddev->raid_disks > 253)
7874                 return ERR_PTR(-EINVAL);
7875         if (mddev->raid_disks < 3)
7876                 return ERR_PTR(-EINVAL);
7877
7878         switch (mddev->layout) {
7879         case ALGORITHM_LEFT_ASYMMETRIC:
7880                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7881                 break;
7882         case ALGORITHM_RIGHT_ASYMMETRIC:
7883                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7884                 break;
7885         case ALGORITHM_LEFT_SYMMETRIC:
7886                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7887                 break;
7888         case ALGORITHM_RIGHT_SYMMETRIC:
7889                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
7890                 break;
7891         case ALGORITHM_PARITY_0:
7892                 new_layout = ALGORITHM_PARITY_0_6;
7893                 break;
7894         case ALGORITHM_PARITY_N:
7895                 new_layout = ALGORITHM_PARITY_N;
7896                 break;
7897         default:
7898                 return ERR_PTR(-EINVAL);
7899         }
7900         mddev->new_level = 6;
7901         mddev->new_layout = new_layout;
7902         mddev->delta_disks = 1;
7903         mddev->raid_disks += 1;
7904         return setup_conf(mddev);
7905 }
7906
7907 static struct md_personality raid6_personality =
7908 {
7909         .name           = "raid6",
7910         .level          = 6,
7911         .owner          = THIS_MODULE,
7912         .make_request   = make_request,
7913         .run            = run,
7914         .free           = raid5_free,
7915         .status         = status,
7916         .error_handler  = error,
7917         .hot_add_disk   = raid5_add_disk,
7918         .hot_remove_disk= raid5_remove_disk,
7919         .spare_active   = raid5_spare_active,
7920         .sync_request   = sync_request,
7921         .resize         = raid5_resize,
7922         .size           = raid5_size,
7923         .check_reshape  = raid6_check_reshape,
7924         .start_reshape  = raid5_start_reshape,
7925         .finish_reshape = raid5_finish_reshape,
7926         .quiesce        = raid5_quiesce,
7927         .takeover       = raid6_takeover,
7928         .congested      = raid5_congested,
7929 };
7930 static struct md_personality raid5_personality =
7931 {
7932         .name           = "raid5",
7933         .level          = 5,
7934         .owner          = THIS_MODULE,
7935         .make_request   = make_request,
7936         .run            = run,
7937         .free           = raid5_free,
7938         .status         = status,
7939         .error_handler  = error,
7940         .hot_add_disk   = raid5_add_disk,
7941         .hot_remove_disk= raid5_remove_disk,
7942         .spare_active   = raid5_spare_active,
7943         .sync_request   = sync_request,
7944         .resize         = raid5_resize,
7945         .size           = raid5_size,
7946         .check_reshape  = raid5_check_reshape,
7947         .start_reshape  = raid5_start_reshape,
7948         .finish_reshape = raid5_finish_reshape,
7949         .quiesce        = raid5_quiesce,
7950         .takeover       = raid5_takeover,
7951         .congested      = raid5_congested,
7952 };
7953
7954 static struct md_personality raid4_personality =
7955 {
7956         .name           = "raid4",
7957         .level          = 4,
7958         .owner          = THIS_MODULE,
7959         .make_request   = make_request,
7960         .run            = run,
7961         .free           = raid5_free,
7962         .status         = status,
7963         .error_handler  = error,
7964         .hot_add_disk   = raid5_add_disk,
7965         .hot_remove_disk= raid5_remove_disk,
7966         .spare_active   = raid5_spare_active,
7967         .sync_request   = sync_request,
7968         .resize         = raid5_resize,
7969         .size           = raid5_size,
7970         .check_reshape  = raid5_check_reshape,
7971         .start_reshape  = raid5_start_reshape,
7972         .finish_reshape = raid5_finish_reshape,
7973         .quiesce        = raid5_quiesce,
7974         .takeover       = raid4_takeover,
7975         .congested      = raid5_congested,
7976 };
7977
7978 static int __init raid5_init(void)
7979 {
7980         raid5_wq = alloc_workqueue("raid5wq",
7981                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
7982         if (!raid5_wq)
7983                 return -ENOMEM;
7984         register_md_personality(&raid6_personality);
7985         register_md_personality(&raid5_personality);
7986         register_md_personality(&raid4_personality);
7987         return 0;
7988 }
7989
7990 static void raid5_exit(void)
7991 {
7992         unregister_md_personality(&raid6_personality);
7993         unregister_md_personality(&raid5_personality);
7994         unregister_md_personality(&raid4_personality);
7995         destroy_workqueue(raid5_wq);
7996 }
7997
7998 module_init(raid5_init);
7999 module_exit(raid5_exit);
8000 MODULE_LICENSE("GPL");
8001 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
8002 MODULE_ALIAS("md-personality-4"); /* RAID5 */
8003 MODULE_ALIAS("md-raid5");
8004 MODULE_ALIAS("md-raid4");
8005 MODULE_ALIAS("md-level-5");
8006 MODULE_ALIAS("md-level-4");
8007 MODULE_ALIAS("md-personality-8"); /* RAID6 */
8008 MODULE_ALIAS("md-raid6");
8009 MODULE_ALIAS("md-level-6");
8010
8011 /* This used to be two separate modules, they were: */
8012 MODULE_ALIAS("raid5");
8013 MODULE_ALIAS("raid6");