drivers/block/drbd/drbd_actlog.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3    drbd_actlog.c
   4
   5    This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
   6
   7    Copyright (C) 2003-2008, LINBIT Information Technologies GmbH.
   8    Copyright (C) 2003-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   9    Copyright (C) 2003-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
  10
  11
  12  */
  13
  14 #include <linux/slab.h>
  15 #include <linux/crc32c.h>
  16 #include <linux/drbd.h>
  17 #include <linux/drbd_limits.h>
  18 #include "drbd_int.h"
  19
  20
  21 enum al_transaction_types {
  22         AL_TR_UPDATE = 0,
  23         AL_TR_INITIALIZED = 0xffff
  24 };
  25 /* all fields on disc in big endian */
  26 struct __packed al_transaction_on_disk {
  27         /* don't we all like magic */
  28         __be32  magic;
  29
  30         /* to identify the most recent transaction block
  31          * in the on disk ring buffer */
  32         __be32  tr_number;
  33
  34         /* checksum on the full 4k block, with this field set to 0. */
  35         __be32  crc32c;
  36
  37         /* type of transaction, special transaction types like:
  38          * purge-all, set-all-idle, set-all-active, ... to-be-defined
  39          * see also enum al_transaction_types */
  40         __be16  transaction_type;
  41
  42         /* we currently allow only a few thousand extents,
  43          * so 16bit will be enough for the slot number. */
  44
  45         /* how many updates in this transaction */
  46         __be16  n_updates;
  47
  48         /* maximum slot number, "al-extents" in drbd.conf speak.
  49          * Having this in each transaction should make reconfiguration
  50          * of that parameter easier. */
  51         __be16  context_size;
  52
  53         /* slot number the context starts with */
  54         __be16  context_start_slot_nr;
  55
  56         /* Some reserved bytes.  Expected usage is a 64bit counter of
  57          * sectors-written since device creation, and other data generation tag
  58          * supporting usage */
  59         __be32  __reserved[4];
  60
  61         /* --- 36 byte used --- */
  62
  63         /* Reserve space for up to AL_UPDATES_PER_TRANSACTION changes
  64          * in one transaction, then use the remaining byte in the 4k block for
  65          * context information.  "Flexible" number of updates per transaction
  66          * does not help, as we have to account for the case when all update
  67          * slots are used anyways, so it would only complicate code without
  68          * additional benefit.
  69          */
  70         __be16  update_slot_nr[AL_UPDATES_PER_TRANSACTION];
  71
  72         /* but the extent number is 32bit, which at an extent size of 4 MiB
  73          * allows to cover device sizes of up to 2**54 Byte (16 PiB) */
  74         __be32  update_extent_nr[AL_UPDATES_PER_TRANSACTION];
  75
  76         /* --- 420 bytes used (36 + 64*6) --- */
  77
  78         /* 4096 - 420 = 3676 = 919 * 4 */
  79         __be32  context[AL_CONTEXT_PER_TRANSACTION];
  80 };
  81
  82 void *drbd_md_get_buffer(struct drbd_device *device, const char *intent)
  83 {
  84         int r;
  85
  86         wait_event(device->misc_wait,
  87                    (r = atomic_cmpxchg(&device->md_io.in_use, 0, 1)) == 0 ||
  88                    device->state.disk <= D_FAILED);
  89
  90         if (r)
  91                 return NULL;
  92
  93         device->md_io.current_use = intent;
  94         device->md_io.start_jif = jiffies;
  95         device->md_io.submit_jif = device->md_io.start_jif - 1;
  96         return page_address(device->md_io.page);
  97 }
  98
  99 void drbd_md_put_buffer(struct drbd_device *device)
 100 {
 101         if (atomic_dec_and_test(&device->md_io.in_use))
 102                 wake_up(&device->misc_wait);
 103 }
 104
 105 void wait_until_done_or_force_detached(struct drbd_device *device, struct drbd_backing_dev *bdev,
 106                                      unsigned int *done)
 107 {
 108         long dt;
 109
 110         rcu_read_lock();
 111         dt = rcu_dereference(bdev->disk_conf)->disk_timeout;
 112         rcu_read_unlock();
 113         dt = dt * HZ / 10;
 114         if (dt == 0)
 115                 dt = MAX_SCHEDULE_TIMEOUT;
 116
 117         dt = wait_event_timeout(device->misc_wait,
 118                         *done || test_bit(FORCE_DETACH, &device->flags), dt);
 119         if (dt == 0) {
 120                 drbd_err(device, "meta-data IO operation timed out\n");
 121                 drbd_chk_io_error(device, 1, DRBD_FORCE_DETACH);
 122         }
 123 }
 124
 125 static int _drbd_md_sync_page_io(struct drbd_device *device,
 126                                  struct drbd_backing_dev *bdev,
 127                                  sector_t sector, int op)
 128 {
 129         struct bio *bio;
 130         /* we do all our meta data IO in aligned 4k blocks. */
 131         const int size = 4096;
 132         int err, op_flags = 0;
 133
 134         device->md_io.done = 0;
 135         device->md_io.error = -ENODEV;
 136
 137         if ((op == REQ_OP_WRITE) && !test_bit(MD_NO_FUA, &device->flags))
 138                 op_flags |= REQ_FUA | REQ_PREFLUSH;
 139         op_flags |= REQ_SYNC;
 140
 141         bio = bio_alloc_bioset(bdev->md_bdev, 1, op | op_flags, GFP_NOIO,
 142                                &drbd_md_io_bio_set);
 143         bio->bi_iter.bi_sector = sector;
 144         err = -EIO;
 145         if (bio_add_page(bio, device->md_io.page, size, 0) != size)
 146                 goto out;
 147         bio->bi_private = device;
 148         bio->bi_end_io = drbd_md_endio;
 149
 150         if (op != REQ_OP_WRITE && device->state.disk == D_DISKLESS && device->ldev == NULL)
 151                 /* special case, drbd_md_read() during drbd_adm_attach(): no get_ldev */
 152                 ;
 153         else if (!get_ldev_if_state(device, D_ATTACHING)) {
 154                 /* Corresponding put_ldev in drbd_md_endio() */
 155                 drbd_err(device, "ASSERT FAILED: get_ldev_if_state() == 1 in _drbd_md_sync_page_io()\n");
 156                 err = -ENODEV;
 157                 goto out;
 158         }
 159
 160         bio_get(bio); /* one bio_put() is in the completion handler */
 161         atomic_inc(&device->md_io.in_use); /* drbd_md_put_buffer() is in the completion handler */
 162         device->md_io.submit_jif = jiffies;
 163         if (drbd_insert_fault(device, (op == REQ_OP_WRITE) ? DRBD_FAULT_MD_WR : DRBD_FAULT_MD_RD))
 164                 bio_io_error(bio);
 165         else
 166                 submit_bio(bio);
 167         wait_until_done_or_force_detached(device, bdev, &device->md_io.done);
 168         if (!bio->bi_status)
 169                 err = device->md_io.error;
 170
 171  out:
 172         bio_put(bio);
 173         return err;
 174 }
 175
 176 int drbd_md_sync_page_io(struct drbd_device *device, struct drbd_backing_dev *bdev,
 177                          sector_t sector, int op)
 178 {
 179         int err;
 180         D_ASSERT(device, atomic_read(&device->md_io.in_use) == 1);
 181
 182         BUG_ON(!bdev->md_bdev);
 183
 184         dynamic_drbd_dbg(device, "meta_data io: %s [%d]:%s(,%llus,%s) %pS\n",
 185              current->comm, current->pid, __func__,
 186              (unsigned long long)sector, (op == REQ_OP_WRITE) ? "WRITE" : "READ",
 187              (void*)_RET_IP_ );
 188
 189         if (sector < drbd_md_first_sector(bdev) ||
 190             sector + 7 > drbd_md_last_sector(bdev))
 191                 drbd_alert(device, "%s [%d]:%s(,%llus,%s) out of range md access!\n",
 192                      current->comm, current->pid, __func__,
 193                      (unsigned long long)sector,
 194                      (op == REQ_OP_WRITE) ? "WRITE" : "READ");
 195
 196         err = _drbd_md_sync_page_io(device, bdev, sector, op);
 197         if (err) {
 198                 drbd_err(device, "drbd_md_sync_page_io(,%llus,%s) failed with error %d\n",
 199                     (unsigned long long)sector,
 200                     (op == REQ_OP_WRITE) ? "WRITE" : "READ", err);
 201         }
 202         return err;
 203 }
 204
 205 static struct bm_extent *find_active_resync_extent(struct drbd_device *device, unsigned int enr)
 206 {
 207         struct lc_element *tmp;
 208         tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 209         if (unlikely(tmp != NULL)) {
 210                 struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 211                 if (test_bit(BME_NO_WRITES, &bm_ext->flags))
 212                         return bm_ext;
 213         }
 214         return NULL;
 215 }
 216
 217 static struct lc_element *_al_get(struct drbd_device *device, unsigned int enr, bool nonblock)
 218 {
 219         struct lc_element *al_ext;
 220         struct bm_extent *bm_ext;
 221         int wake;
 222
 223         spin_lock_irq(&device->al_lock);
 224         bm_ext = find_active_resync_extent(device, enr);
 225         if (bm_ext) {
 226                 wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags);
 227                 spin_unlock_irq(&device->al_lock);
 228                 if (wake)
 229                         wake_up(&device->al_wait);
 230                 return NULL;
 231         }
 232         if (nonblock)
 233                 al_ext = lc_try_get(device->act_log, enr);
 234         else
 235                 al_ext = lc_get(device->act_log, enr);
 236         spin_unlock_irq(&device->al_lock);
 237         return al_ext;
 238 }
 239
 240 bool drbd_al_begin_io_fastpath(struct drbd_device *device, struct drbd_interval *i)
 241 {
 242         /* for bios crossing activity log extent boundaries,
 243          * we may need to activate two extents in one go */
 244         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 245         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 246
 247         D_ASSERT(device, first <= last);
 248         D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 249
 250         /* FIXME figure out a fast path for bios crossing AL extent boundaries */
 251         if (first != last)
 252                 return false;
 253
 254         return _al_get(device, first, true);
 255 }
 256
 257 bool drbd_al_begin_io_prepare(struct drbd_device *device, struct drbd_interval *i)
 258 {
 259         /* for bios crossing activity log extent boundaries,
 260          * we may need to activate two extents in one go */
 261         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 262         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 263         unsigned enr;
 264         bool need_transaction = false;
 265
 266         D_ASSERT(device, first <= last);
 267         D_ASSERT(device, atomic_read(&device->local_cnt) > 0);
 268
 269         for (enr = first; enr <= last; enr++) {
 270                 struct lc_element *al_ext;
 271                 wait_event(device->al_wait,
 272                                 (al_ext = _al_get(device, enr, false)) != NULL);
 273                 if (al_ext->lc_number != enr)
 274                         need_transaction = true;
 275         }
 276         return need_transaction;
 277 }
 278
 279 #if (PAGE_SHIFT + 3) < (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT)
 280 /* Currently BM_BLOCK_SHIFT, BM_EXT_SHIFT and AL_EXTENT_SHIFT
 281  * are still coupled, or assume too much about their relation.
 282  * Code below will not work if this is violated.
 283  * Will be cleaned up with some followup patch.
 284  */
 285 # error FIXME
 286 #endif
 287
 288 static unsigned int al_extent_to_bm_page(unsigned int al_enr)
 289 {
 290         return al_enr >>
 291                 /* bit to page */
 292                 ((PAGE_SHIFT + 3) -
 293                 /* al extent number to bit */
 294                  (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT));
 295 }
 296
 297 static sector_t al_tr_number_to_on_disk_sector(struct drbd_device *device)
 298 {
 299         const unsigned int stripes = device->ldev->md.al_stripes;
 300         const unsigned int stripe_size_4kB = device->ldev->md.al_stripe_size_4k;
 301
 302         /* transaction number, modulo on-disk ring buffer wrap around */
 303         unsigned int t = device->al_tr_number % (device->ldev->md.al_size_4k);
 304
 305         /* ... to aligned 4k on disk block */
 306         t = ((t % stripes) * stripe_size_4kB) + t/stripes;
 307
 308         /* ... to 512 byte sector in activity log */
 309         t *= 8;
 310
 311         /* ... plus offset to the on disk position */
 312         return device->ldev->md.md_offset + device->ldev->md.al_offset + t;
 313 }
 314
 315 static int __al_write_transaction(struct drbd_device *device, struct al_transaction_on_disk *buffer)
 316 {
 317         struct lc_element *e;
 318         sector_t sector;
 319         int i, mx;
 320         unsigned extent_nr;
 321         unsigned crc = 0;
 322         int err = 0;
 323
 324         memset(buffer, 0, sizeof(*buffer));
 325         buffer->magic = cpu_to_be32(DRBD_AL_MAGIC);
 326         buffer->tr_number = cpu_to_be32(device->al_tr_number);
 327
 328         i = 0;
 329
 330         drbd_bm_reset_al_hints(device);
 331
 332         /* Even though no one can start to change this list
 333          * once we set the LC_LOCKED -- from drbd_al_begin_io(),
 334          * lc_try_lock_for_transaction() --, someone may still
 335          * be in the process of changing it. */
 336         spin_lock_irq(&device->al_lock);
 337         list_for_each_entry(e, &device->act_log->to_be_changed, list) {
 338                 if (i == AL_UPDATES_PER_TRANSACTION) {
 339                         i++;
 340                         break;
 341                 }
 342                 buffer->update_slot_nr[i] = cpu_to_be16(e->lc_index);
 343                 buffer->update_extent_nr[i] = cpu_to_be32(e->lc_new_number);
 344                 if (e->lc_number != LC_FREE)
 345                         drbd_bm_mark_for_writeout(device,
 346                                         al_extent_to_bm_page(e->lc_number));
 347                 i++;
 348         }
 349         spin_unlock_irq(&device->al_lock);
 350         BUG_ON(i > AL_UPDATES_PER_TRANSACTION);
 351
 352         buffer->n_updates = cpu_to_be16(i);
 353         for ( ; i < AL_UPDATES_PER_TRANSACTION; i++) {
 354                 buffer->update_slot_nr[i] = cpu_to_be16(-1);
 355                 buffer->update_extent_nr[i] = cpu_to_be32(LC_FREE);
 356         }
 357
 358         buffer->context_size = cpu_to_be16(device->act_log->nr_elements);
 359         buffer->context_start_slot_nr = cpu_to_be16(device->al_tr_cycle);
 360
 361         mx = min_t(int, AL_CONTEXT_PER_TRANSACTION,
 362                    device->act_log->nr_elements - device->al_tr_cycle);
 363         for (i = 0; i < mx; i++) {
 364                 unsigned idx = device->al_tr_cycle + i;
 365                 extent_nr = lc_element_by_index(device->act_log, idx)->lc_number;
 366                 buffer->context[i] = cpu_to_be32(extent_nr);
 367         }
 368         for (; i < AL_CONTEXT_PER_TRANSACTION; i++)
 369                 buffer->context[i] = cpu_to_be32(LC_FREE);
 370
 371         device->al_tr_cycle += AL_CONTEXT_PER_TRANSACTION;
 372         if (device->al_tr_cycle >= device->act_log->nr_elements)
 373                 device->al_tr_cycle = 0;
 374
 375         sector = al_tr_number_to_on_disk_sector(device);
 376
 377         crc = crc32c(0, buffer, 4096);
 378         buffer->crc32c = cpu_to_be32(crc);
 379
 380         if (drbd_bm_write_hinted(device))
 381                 err = -EIO;
 382         else {
 383                 bool write_al_updates;
 384                 rcu_read_lock();
 385                 write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 386                 rcu_read_unlock();
 387                 if (write_al_updates) {
 388                         if (drbd_md_sync_page_io(device, device->ldev, sector, WRITE)) {
 389                                 err = -EIO;
 390                                 drbd_chk_io_error(device, 1, DRBD_META_IO_ERROR);
 391                         } else {
 392                                 device->al_tr_number++;
 393                                 device->al_writ_cnt++;
 394                         }
 395                 }
 396         }
 397
 398         return err;
 399 }
 400
 401 static int al_write_transaction(struct drbd_device *device)
 402 {
 403         struct al_transaction_on_disk *buffer;
 404         int err;
 405
 406         if (!get_ldev(device)) {
 407                 drbd_err(device, "disk is %s, cannot start al transaction\n",
 408                         drbd_disk_str(device->state.disk));
 409                 return -EIO;
 410         }
 411
 412         /* The bitmap write may have failed, causing a state change. */
 413         if (device->state.disk < D_INCONSISTENT) {
 414                 drbd_err(device,
 415                         "disk is %s, cannot write al transaction\n",
 416                         drbd_disk_str(device->state.disk));
 417                 put_ldev(device);
 418                 return -EIO;
 419         }
 420
 421         /* protects md_io_buffer, al_tr_cycle, ... */
 422         buffer = drbd_md_get_buffer(device, __func__);
 423         if (!buffer) {
 424                 drbd_err(device, "disk failed while waiting for md_io buffer\n");
 425                 put_ldev(device);
 426                 return -ENODEV;
 427         }
 428
 429         err = __al_write_transaction(device, buffer);
 430
 431         drbd_md_put_buffer(device);
 432         put_ldev(device);
 433
 434         return err;
 435 }
 436
 437
 438 void drbd_al_begin_io_commit(struct drbd_device *device)
 439 {
 440         bool locked = false;
 441
 442         /* Serialize multiple transactions.
 443          * This uses test_and_set_bit, memory barrier is implicit.
 444          */
 445         wait_event(device->al_wait,
 446                         device->act_log->pending_changes == 0 ||
 447                         (locked = lc_try_lock_for_transaction(device->act_log)));
 448
 449         if (locked) {
 450                 /* Double check: it may have been committed by someone else,
 451                  * while we have been waiting for the lock. */
 452                 if (device->act_log->pending_changes) {
 453                         bool write_al_updates;
 454
 455                         rcu_read_lock();
 456                         write_al_updates = rcu_dereference(device->ldev->disk_conf)->al_updates;
 457                         rcu_read_unlock();
 458
 459                         if (write_al_updates)
 460                                 al_write_transaction(device);
 461                         spin_lock_irq(&device->al_lock);
 462                         /* FIXME
 463                         if (err)
 464                                 we need an "lc_cancel" here;
 465                         */
 466                         lc_committed(device->act_log);
 467                         spin_unlock_irq(&device->al_lock);
 468                 }
 469                 lc_unlock(device->act_log);
 470                 wake_up(&device->al_wait);
 471         }
 472 }
 473
 474 /*
 475  * @delegate:   delegate activity log I/O to the worker thread
 476  */
 477 void drbd_al_begin_io(struct drbd_device *device, struct drbd_interval *i)
 478 {
 479         if (drbd_al_begin_io_prepare(device, i))
 480                 drbd_al_begin_io_commit(device);
 481 }
 482
 483 int drbd_al_begin_io_nonblock(struct drbd_device *device, struct drbd_interval *i)
 484 {
 485         struct lru_cache *al = device->act_log;
 486         /* for bios crossing activity log extent boundaries,
 487          * we may need to activate two extents in one go */
 488         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 489         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 490         unsigned nr_al_extents;
 491         unsigned available_update_slots;
 492         unsigned enr;
 493
 494         D_ASSERT(device, first <= last);
 495
 496         nr_al_extents = 1 + last - first; /* worst case: all touched extends are cold. */
 497         available_update_slots = min(al->nr_elements - al->used,
 498                                 al->max_pending_changes - al->pending_changes);
 499
 500         /* We want all necessary updates for a given request within the same transaction
 501          * We could first check how many updates are *actually* needed,
 502          * and use that instead of the worst-case nr_al_extents */
 503         if (available_update_slots < nr_al_extents) {
 504                 /* Too many activity log extents are currently "hot".
 505                  *
 506                  * If we have accumulated pending changes already,
 507                  * we made progress.
 508                  *
 509                  * If we cannot get even a single pending change through,
 510                  * stop the fast path until we made some progress,
 511                  * or requests to "cold" extents could be starved. */
 512                 if (!al->pending_changes)
 513                         __set_bit(__LC_STARVING, &device->act_log->flags);
 514                 return -ENOBUFS;
 515         }
 516
 517         /* Is resync active in this area? */
 518         for (enr = first; enr <= last; enr++) {
 519                 struct lc_element *tmp;
 520                 tmp = lc_find(device->resync, enr/AL_EXT_PER_BM_SECT);
 521                 if (unlikely(tmp != NULL)) {
 522                         struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
 523                         if (test_bit(BME_NO_WRITES, &bm_ext->flags)) {
 524                                 if (!test_and_set_bit(BME_PRIORITY, &bm_ext->flags))
 525                                         return -EBUSY;
 526                                 return -EWOULDBLOCK;
 527                         }
 528                 }
 529         }
 530
 531         /* Checkout the refcounts.
 532          * Given that we checked for available elements and update slots above,
 533          * this has to be successful. */
 534         for (enr = first; enr <= last; enr++) {
 535                 struct lc_element *al_ext;
 536                 al_ext = lc_get_cumulative(device->act_log, enr);
 537                 if (!al_ext)
 538                         drbd_info(device, "LOGIC BUG for enr=%u\n", enr);
 539         }
 540         return 0;
 541 }
 542
 543 void drbd_al_complete_io(struct drbd_device *device, struct drbd_interval *i)
 544 {
 545         /* for bios crossing activity log extent boundaries,
 546          * we may need to activate two extents in one go */
 547         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
 548         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
 549         unsigned enr;
 550         struct lc_element *extent;
 551         unsigned long flags;
 552
 553         D_ASSERT(device, first <= last);
 554         spin_lock_irqsave(&device->al_lock, flags);
 555
 556         for (enr = first; enr <= last; enr++) {
 557                 extent = lc_find(device->act_log, enr);
 558                 if (!extent) {
 559                         drbd_err(device, "al_complete_io() called on inactive extent %u\n", enr);
 560                         continue;
 561                 }
 562                 lc_put(device->act_log, extent);
 563         }
 564         spin_unlock_irqrestore(&device->al_lock, flags);
 565         wake_up(&device->al_wait);
 566 }
 567
 568 static int _try_lc_del(struct drbd_device *device, struct lc_element *al_ext)
 569 {
 570         int rv;
 571
 572         spin_lock_irq(&device->al_lock);
 573         rv = (al_ext->refcnt == 0);
 574         if (likely(rv))
 575                 lc_del(device->act_log, al_ext);
 576         spin_unlock_irq(&device->al_lock);
 577
 578         return rv;
 579 }
 580
 581 /**
 582  * drbd_al_shrink() - Removes all active extents form the activity log
 583  * @device:     DRBD device.
 584  *
 585  * Removes all active extents form the activity log, waiting until
 586  * the reference count of each entry dropped to 0 first, of course.
 587  *
 588  * You need to lock device->act_log with lc_try_lock() / lc_unlock()
 589  */
 590 void drbd_al_shrink(struct drbd_device *device)
 591 {
 592         struct lc_element *al_ext;
 593         int i;
 594
 595         D_ASSERT(device, test_bit(__LC_LOCKED, &device->act_log->flags));
 596
 597         for (i = 0; i < device->act_log->nr_elements; i++) {
 598                 al_ext = lc_element_by_index(device->act_log, i);
 599                 if (al_ext->lc_number == LC_FREE)
 600                         continue;
 601                 wait_event(device->al_wait, _try_lc_del(device, al_ext));
 602         }
 603
 604         wake_up(&device->al_wait);
 605 }
 606
 607 int drbd_al_initialize(struct drbd_device *device, void *buffer)
 608 {
 609         struct al_transaction_on_disk *al = buffer;
 610         struct drbd_md *md = &device->ldev->md;
 611         int al_size_4k = md->al_stripes * md->al_stripe_size_4k;
 612         int i;
 613
 614         __al_write_transaction(device, al);
 615         /* There may or may not have been a pending transaction. */
 616         spin_lock_irq(&device->al_lock);
 617         lc_committed(device->act_log);
 618         spin_unlock_irq(&device->al_lock);
 619
 620         /* The rest of the transactions will have an empty "updates" list, and
 621          * are written out only to provide the context, and to initialize the
 622          * on-disk ring buffer. */
 623         for (i = 1; i < al_size_4k; i++) {
 624                 int err = __al_write_transaction(device, al);
 625                 if (err)
 626                         return err;
 627         }
 628         return 0;
 629 }
 630
 631 static const char *drbd_change_sync_fname[] = {
 632         [RECORD_RS_FAILED] = "drbd_rs_failed_io",
 633         [SET_IN_SYNC] = "drbd_set_in_sync",
 634         [SET_OUT_OF_SYNC] = "drbd_set_out_of_sync"
 635 };
 636
 637 /* ATTENTION. The AL's extents are 4MB each, while the extents in the
 638  * resync LRU-cache are 16MB each.
 639  * The caller of this function has to hold an get_ldev() reference.
 640  *
 641  * Adjusts the caching members ->rs_left (success) or ->rs_failed (!success),
 642  * potentially pulling in (and recounting the corresponding bits)
 643  * this resync extent into the resync extent lru cache.
 644  *
 645  * Returns whether all bits have been cleared for this resync extent,
 646  * precisely: (rs_left <= rs_failed)
 647  *
 648  * TODO will be obsoleted once we have a caching lru of the on disk bitmap
 649  */
 650 static bool update_rs_extent(struct drbd_device *device,
 651                 unsigned int enr, int count,
 652                 enum update_sync_bits_mode mode)
 653 {
 654         struct lc_element *e;
 655
 656         D_ASSERT(device, atomic_read(&device->local_cnt));
 657
 658         /* When setting out-of-sync bits,
 659          * we don't need it cached (lc_find).
 660          * But if it is present in the cache,
 661          * we should update the cached bit count.
 662          * Otherwise, that extent should be in the resync extent lru cache
 663          * already -- or we want to pull it in if necessary -- (lc_get),
 664          * then update and check rs_left and rs_failed. */
 665         if (mode == SET_OUT_OF_SYNC)
 666                 e = lc_find(device->resync, enr);
 667         else
 668                 e = lc_get(device->resync, enr);
 669         if (e) {
 670                 struct bm_extent *ext = lc_entry(e, struct bm_extent, lce);
 671                 if (ext->lce.lc_number == enr) {
 672                         if (mode == SET_IN_SYNC)
 673                                 ext->rs_left -= count;
 674                         else if (mode == SET_OUT_OF_SYNC)
 675                                 ext->rs_left += count;
 676                         else
 677                                 ext->rs_failed += count;
 678                         if (ext->rs_left < ext->rs_failed) {
 679                                 drbd_warn(device, "BAD! enr=%u rs_left=%d "
 680                                     "rs_failed=%d count=%d cstate=%s\n",
 681                                      ext->lce.lc_number, ext->rs_left,
 682                                      ext->rs_failed, count,
 683                                      drbd_conn_str(device->state.conn));
 684
 685                                 /* We don't expect to be able to clear more bits
 686                                  * than have been set when we originally counted
 687                                  * the set bits to cache that value in ext->rs_left.
 688                                  * Whatever the reason (disconnect during resync,
 689                                  * delayed local completion of an application write),
 690                                  * try to fix it up by recounting here. */
 691                                 ext->rs_left = drbd_bm_e_weight(device, enr);
 692                         }
 693                 } else {
 694                         /* Normally this element should be in the cache,
 695                          * since drbd_rs_begin_io() pulled it already in.
 696                          *
 697                          * But maybe an application write finished, and we set
 698                          * something outside the resync lru_cache in sync.
 699                          */
 700                         int rs_left = drbd_bm_e_weight(device, enr);
 701                         if (ext->flags != 0) {
 702                                 drbd_warn(device, "changing resync lce: %d[%u;%02lx]"
 703                                      " -> %d[%u;00]\n",
 704                                      ext->lce.lc_number, ext->rs_left,
 705                                      ext->flags, enr, rs_left);
 706                                 ext->flags = 0;
 707                         }
 708                         if (ext->rs_failed) {
 709                                 drbd_warn(device, "Kicking resync_lru element enr=%u "
 710                                      "out with rs_failed=%d\n",
 711                                      ext->lce.lc_number, ext->rs_failed);
 712                         }
 713                         ext->rs_left = rs_left;
 714                         ext->rs_failed = (mode == RECORD_RS_FAILED) ? count : 0;
 715                         /* we don't keep a persistent log of the resync lru,
 716                          * we can commit any change right away. */
 717                         lc_committed(device->resync);
 718                 }
 719                 if (mode != SET_OUT_OF_SYNC)
 720                         lc_put(device->resync, &ext->lce);
 721                 /* no race, we are within the al_lock! */
 722
 723                 if (ext->rs_left <= ext->rs_failed) {
 724                         ext->rs_failed = 0;
 725                         return true;
 726                 }
 727         } else if (mode != SET_OUT_OF_SYNC) {
 728                 /* be quiet if lc_find() did not find it. */
 729                 drbd_err(device, "lc_get() failed! locked=%d/%d flags=%lu\n",
 730                     device->resync_locked,
 731                     device->resync->nr_elements,
 732                     device->resync->flags);
 733         }
 734         return false;
 735 }
 736
 737 void drbd_advance_rs_marks(struct drbd_device *device, unsigned long still_to_go)
 738 {
 739         unsigned long now = jiffies;
 740         unsigned long last = device->rs_mark_time[device->rs_last_mark];
 741         int next = (device->rs_last_mark + 1) % DRBD_SYNC_MARKS;
 742         if (time_after_eq(now, last + DRBD_SYNC_MARK_STEP)) {
 743                 if (device->rs_mark_left[device->rs_last_mark] != still_to_go &&
 744                     device->state.conn != C_PAUSED_SYNC_T &&
 745                     device->state.conn != C_PAUSED_SYNC_S) {
 746                         device->rs_mark_time[next] = now;
 747                         device->rs_mark_left[next] = still_to_go;
 748                         device->rs_last_mark = next;
 749                 }
 750         }
 751 }
 752
 753 /* It is called lazy update, so don't do write-out too often. */
 754 static bool lazy_bitmap_update_due(struct drbd_device *device)
 755 {
 756         return time_after(jiffies, device->rs_last_bcast + 2*HZ);
 757 }
 758
 759 static void maybe_schedule_on_disk_bitmap_update(struct drbd_device *device, bool rs_done)
 760 {
 761         if (rs_done) {
 762                 struct drbd_connection *connection = first_peer_device(device)->connection;
 763                 if (connection->agreed_pro_version <= 95 ||
 764                     is_sync_target_state(device->state.conn))
 765                         set_bit(RS_DONE, &device->flags);
 766                         /* and also set RS_PROGRESS below */
 767
 768                 /* Else: rather wait for explicit notification via receive_state,
 769                  * to avoid uuids-rotated-too-fast causing full resync
 770                  * in next handshake, in case the replication link breaks
 771                  * at the most unfortunate time... */
 772         } else if (!lazy_bitmap_update_due(device))
 773                 return;
 774
 775         drbd_device_post_work(device, RS_PROGRESS);
 776 }
 777
 778 static int update_sync_bits(struct drbd_device *device,
 779                 unsigned long sbnr, unsigned long ebnr,
 780                 enum update_sync_bits_mode mode)
 781 {
 782         /*
 783          * We keep a count of set bits per resync-extent in the ->rs_left
 784          * caching member, so we need to loop and work within the resync extent
 785          * alignment. Typically this loop will execute exactly once.
 786          */
 787         unsigned long flags;
 788         unsigned long count = 0;
 789         unsigned int cleared = 0;
 790         while (sbnr <= ebnr) {
 791                 /* set temporary boundary bit number to last bit number within
 792                  * the resync extent of the current start bit number,
 793                  * but cap at provided end bit number */
 794                 unsigned long tbnr = min(ebnr, sbnr | BM_BLOCKS_PER_BM_EXT_MASK);
 795                 unsigned long c;
 796
 797                 if (mode == RECORD_RS_FAILED)
 798                         /* Only called from drbd_rs_failed_io(), bits
 799                          * supposedly still set.  Recount, maybe some
 800                          * of the bits have been successfully cleared
 801                          * by application IO meanwhile.
 802                          */
 803                         c = drbd_bm_count_bits(device, sbnr, tbnr);
 804                 else if (mode == SET_IN_SYNC)
 805                         c = drbd_bm_clear_bits(device, sbnr, tbnr);
 806                 else /* if (mode == SET_OUT_OF_SYNC) */
 807                         c = drbd_bm_set_bits(device, sbnr, tbnr);
 808
 809                 if (c) {
 810                         spin_lock_irqsave(&device->al_lock, flags);
 811                         cleared += update_rs_extent(device, BM_BIT_TO_EXT(sbnr), c, mode);
 812                         spin_unlock_irqrestore(&device->al_lock, flags);
 813                         count += c;
 814                 }
 815                 sbnr = tbnr + 1;
 816         }
 817         if (count) {
 818                 if (mode == SET_IN_SYNC) {
 819                         unsigned long still_to_go = drbd_bm_total_weight(device);
 820                         bool rs_is_done = (still_to_go <= device->rs_failed);
 821                         drbd_advance_rs_marks(device, still_to_go);
 822                         if (cleared || rs_is_done)
 823                                 maybe_schedule_on_disk_bitmap_update(device, rs_is_done);
 824                 } else if (mode == RECORD_RS_FAILED)
 825                         device->rs_failed += count;
 826                 wake_up(&device->al_wait);
 827         }
 828         return count;
 829 }
 830
 831 static bool plausible_request_size(int size)
 832 {
 833         return size > 0
 834                 && size <= DRBD_MAX_BATCH_BIO_SIZE
 835                 && IS_ALIGNED(size, 512);
 836 }
 837
 838 /* clear the bit corresponding to the piece of storage in question:
 839  * size byte of data starting from sector.  Only clear a bits of the affected
 840  * one ore more _aligned_ BM_BLOCK_SIZE blocks.
 841  *
 842  * called by worker on C_SYNC_TARGET and receiver on SyncSource.
 843  *
 844  */
 845 int __drbd_change_sync(struct drbd_device *device, sector_t sector, int size,
 846                 enum update_sync_bits_mode mode)
 847 {
 848         /* Is called from worker and receiver context _only_ */
 849         unsigned long sbnr, ebnr, lbnr;
 850         unsigned long count = 0;
 851         sector_t esector, nr_sectors;
 852
 853         /* This would be an empty REQ_PREFLUSH, be silent. */
 854         if ((mode == SET_OUT_OF_SYNC) && size == 0)
 855                 return 0;
 856
 857         if (!plausible_request_size(size)) {
 858                 drbd_err(device, "%s: sector=%llus size=%d nonsense!\n",
 859                                 drbd_change_sync_fname[mode],
 860                                 (unsigned long long)sector, size);
 861                 return 0;
 862         }
 863
 864         if (!get_ldev(device))
 865                 return 0; /* no disk, no metadata, no bitmap to manipulate bits in */
 866
 867         nr_sectors = get_capacity(device->vdisk);
 868         esector = sector + (size >> 9) - 1;
 869
 870         if (!expect(sector < nr_sectors))
 871                 goto out;
 872         if (!expect(esector < nr_sectors))
 873                 esector = nr_sectors - 1;
 874
 875         lbnr = BM_SECT_TO_BIT(nr_sectors-1);
 876
 877         if (mode == SET_IN_SYNC) {
 878                 /* Round up start sector, round down end sector.  We make sure
 879                  * we only clear full, aligned, BM_BLOCK_SIZE blocks. */
 880                 if (unlikely(esector < BM_SECT_PER_BIT-1))
 881                         goto out;
 882                 if (unlikely(esector == (nr_sectors-1)))
 883                         ebnr = lbnr;
 884                 else
 885                         ebnr = BM_SECT_TO_BIT(esector - (BM_SECT_PER_BIT-1));
 886                 sbnr = BM_SECT_TO_BIT(sector + BM_SECT_PER_BIT-1);
 887         } else {
 888                 /* We set it out of sync, or record resync failure.
 889                  * Should not round anything here. */
 890                 sbnr = BM_SECT_TO_BIT(sector);
 891                 ebnr = BM_SECT_TO_BIT(esector);
 892         }
 893
 894         count = update_sync_bits(device, sbnr, ebnr, mode);
 895 out:
 896         put_ldev(device);
 897         return count;
 898 }
 899
 900 static
 901 struct bm_extent *_bme_get(struct drbd_device *device, unsigned int enr)
 902 {
 903         struct lc_element *e;
 904         struct bm_extent *bm_ext;
 905         int wakeup = 0;
 906         unsigned long rs_flags;
 907
 908         spin_lock_irq(&device->al_lock);
 909         if (device->resync_locked > device->resync->nr_elements/2) {
 910                 spin_unlock_irq(&device->al_lock);
 911                 return NULL;
 912         }
 913         e = lc_get(device->resync, enr);
 914         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
 915         if (bm_ext) {
 916                 if (bm_ext->lce.lc_number != enr) {
 917                         bm_ext->rs_left = drbd_bm_e_weight(device, enr);
 918                         bm_ext->rs_failed = 0;
 919                         lc_committed(device->resync);
 920                         wakeup = 1;
 921                 }
 922                 if (bm_ext->lce.refcnt == 1)
 923                         device->resync_locked++;
 924                 set_bit(BME_NO_WRITES, &bm_ext->flags);
 925         }
 926         rs_flags = device->resync->flags;
 927         spin_unlock_irq(&device->al_lock);
 928         if (wakeup)
 929                 wake_up(&device->al_wait);
 930
 931         if (!bm_ext) {
 932                 if (rs_flags & LC_STARVING)
 933                         drbd_warn(device, "Have to wait for element"
 934                              " (resync LRU too small?)\n");
 935                 BUG_ON(rs_flags & LC_LOCKED);
 936         }
 937
 938         return bm_ext;
 939 }
 940
 941 static int _is_in_al(struct drbd_device *device, unsigned int enr)
 942 {
 943         int rv;
 944
 945         spin_lock_irq(&device->al_lock);
 946         rv = lc_is_used(device->act_log, enr);
 947         spin_unlock_irq(&device->al_lock);
 948
 949         return rv;
 950 }
 951
 952 /**
 953  * drbd_rs_begin_io() - Gets an extent in the resync LRU cache and sets it to BME_LOCKED
 954  * @device:     DRBD device.
 955  * @sector:     The sector number.
 956  *
 957  * This functions sleeps on al_wait. Returns 0 on success, -EINTR if interrupted.
 958  */
 959 int drbd_rs_begin_io(struct drbd_device *device, sector_t sector)
 960 {
 961         unsigned int enr = BM_SECT_TO_EXT(sector);
 962         struct bm_extent *bm_ext;
 963         int i, sig;
 964         bool sa;
 965
 966 retry:
 967         sig = wait_event_interruptible(device->al_wait,
 968                         (bm_ext = _bme_get(device, enr)));
 969         if (sig)
 970                 return -EINTR;
 971
 972         if (test_bit(BME_LOCKED, &bm_ext->flags))
 973                 return 0;
 974
 975         /* step aside only while we are above c-min-rate; unless disabled. */
 976         sa = drbd_rs_c_min_rate_throttle(device);
 977
 978         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
 979                 sig = wait_event_interruptible(device->al_wait,
 980                                                !_is_in_al(device, enr * AL_EXT_PER_BM_SECT + i) ||
 981                                                (sa && test_bit(BME_PRIORITY, &bm_ext->flags)));
 982
 983                 if (sig || (sa && test_bit(BME_PRIORITY, &bm_ext->flags))) {
 984                         spin_lock_irq(&device->al_lock);
 985                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
 986                                 bm_ext->flags = 0; /* clears BME_NO_WRITES and eventually BME_PRIORITY */
 987                                 device->resync_locked--;
 988                                 wake_up(&device->al_wait);
 989                         }
 990                         spin_unlock_irq(&device->al_lock);
 991                         if (sig)
 992                                 return -EINTR;
 993                         if (schedule_timeout_interruptible(HZ/10))
 994                                 return -EINTR;
 995                         goto retry;
 996                 }
 997         }
 998         set_bit(BME_LOCKED, &bm_ext->flags);
 999         return 0;
1000 }
1001
1002 /**
1003  * drbd_try_rs_begin_io() - Gets an extent in the resync LRU cache, does not sleep
1004  * @device:     DRBD device.
1005  * @sector:     The sector number.
1006  *
1007  * Gets an extent in the resync LRU cache, sets it to BME_NO_WRITES, then
1008  * tries to set it to BME_LOCKED. Returns 0 upon success, and -EAGAIN
1009  * if there is still application IO going on in this area.
1010  */
1011 int drbd_try_rs_begin_io(struct drbd_device *device, sector_t sector)
1012 {
1013         unsigned int enr = BM_SECT_TO_EXT(sector);
1014         const unsigned int al_enr = enr*AL_EXT_PER_BM_SECT;
1015         struct lc_element *e;
1016         struct bm_extent *bm_ext;
1017         int i;
1018         bool throttle = drbd_rs_should_slow_down(device, sector, true);
1019
1020         /* If we need to throttle, a half-locked (only marked BME_NO_WRITES,
1021          * not yet BME_LOCKED) extent needs to be kicked out explicitly if we
1022          * need to throttle. There is at most one such half-locked extent,
1023          * which is remembered in resync_wenr. */
1024
1025         if (throttle && device->resync_wenr != enr)
1026                 return -EAGAIN;
1027
1028         spin_lock_irq(&device->al_lock);
1029         if (device->resync_wenr != LC_FREE && device->resync_wenr != enr) {
1030                 /* in case you have very heavy scattered io, it may
1031                  * stall the syncer undefined if we give up the ref count
1032                  * when we try again and requeue.
1033                  *
1034                  * if we don't give up the refcount, but the next time
1035                  * we are scheduled this extent has been "synced" by new
1036                  * application writes, we'd miss the lc_put on the
1037                  * extent we keep the refcount on.
1038                  * so we remembered which extent we had to try again, and
1039                  * if the next requested one is something else, we do
1040                  * the lc_put here...
1041                  * we also have to wake_up
1042                  */
1043                 e = lc_find(device->resync, device->resync_wenr);
1044                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1045                 if (bm_ext) {
1046                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1047                         D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1048                         clear_bit(BME_NO_WRITES, &bm_ext->flags);
1049                         device->resync_wenr = LC_FREE;
1050                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1051                                 bm_ext->flags = 0;
1052                                 device->resync_locked--;
1053                         }
1054                         wake_up(&device->al_wait);
1055                 } else {
1056                         drbd_alert(device, "LOGIC BUG\n");
1057                 }
1058         }
1059         /* TRY. */
1060         e = lc_try_get(device->resync, enr);
1061         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1062         if (bm_ext) {
1063                 if (test_bit(BME_LOCKED, &bm_ext->flags))
1064                         goto proceed;
1065                 if (!test_and_set_bit(BME_NO_WRITES, &bm_ext->flags)) {
1066                         device->resync_locked++;
1067                 } else {
1068                         /* we did set the BME_NO_WRITES,
1069                          * but then could not set BME_LOCKED,
1070                          * so we tried again.
1071                          * drop the extra reference. */
1072                         bm_ext->lce.refcnt--;
1073                         D_ASSERT(device, bm_ext->lce.refcnt > 0);
1074                 }
1075                 goto check_al;
1076         } else {
1077                 /* do we rather want to try later? */
1078                 if (device->resync_locked > device->resync->nr_elements-3)
1079                         goto try_again;
1080                 /* Do or do not. There is no try. -- Yoda */
1081                 e = lc_get(device->resync, enr);
1082                 bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1083                 if (!bm_ext) {
1084                         const unsigned long rs_flags = device->resync->flags;
1085                         if (rs_flags & LC_STARVING)
1086                                 drbd_warn(device, "Have to wait for element"
1087                                      " (resync LRU too small?)\n");
1088                         BUG_ON(rs_flags & LC_LOCKED);
1089                         goto try_again;
1090                 }
1091                 if (bm_ext->lce.lc_number != enr) {
1092                         bm_ext->rs_left = drbd_bm_e_weight(device, enr);
1093                         bm_ext->rs_failed = 0;
1094                         lc_committed(device->resync);
1095                         wake_up(&device->al_wait);
1096                         D_ASSERT(device, test_bit(BME_LOCKED, &bm_ext->flags) == 0);
1097                 }
1098                 set_bit(BME_NO_WRITES, &bm_ext->flags);
1099                 D_ASSERT(device, bm_ext->lce.refcnt == 1);
1100                 device->resync_locked++;
1101                 goto check_al;
1102         }
1103 check_al:
1104         for (i = 0; i < AL_EXT_PER_BM_SECT; i++) {
1105                 if (lc_is_used(device->act_log, al_enr+i))
1106                         goto try_again;
1107         }
1108         set_bit(BME_LOCKED, &bm_ext->flags);
1109 proceed:
1110         device->resync_wenr = LC_FREE;
1111         spin_unlock_irq(&device->al_lock);
1112         return 0;
1113
1114 try_again:
1115         if (bm_ext) {
1116                 if (throttle) {
1117                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1118                         D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1119                         clear_bit(BME_NO_WRITES, &bm_ext->flags);
1120                         device->resync_wenr = LC_FREE;
1121                         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1122                                 bm_ext->flags = 0;
1123                                 device->resync_locked--;
1124                         }
1125                         wake_up(&device->al_wait);
1126                 } else
1127                         device->resync_wenr = enr;
1128         }
1129         spin_unlock_irq(&device->al_lock);
1130         return -EAGAIN;
1131 }
1132
1133 void drbd_rs_complete_io(struct drbd_device *device, sector_t sector)
1134 {
1135         unsigned int enr = BM_SECT_TO_EXT(sector);
1136         struct lc_element *e;
1137         struct bm_extent *bm_ext;
1138         unsigned long flags;
1139
1140         spin_lock_irqsave(&device->al_lock, flags);
1141         e = lc_find(device->resync, enr);
1142         bm_ext = e ? lc_entry(e, struct bm_extent, lce) : NULL;
1143         if (!bm_ext) {
1144                 spin_unlock_irqrestore(&device->al_lock, flags);
1145                 if (__ratelimit(&drbd_ratelimit_state))
1146                         drbd_err(device, "drbd_rs_complete_io() called, but extent not found\n");
1147                 return;
1148         }
1149
1150         if (bm_ext->lce.refcnt == 0) {
1151                 spin_unlock_irqrestore(&device->al_lock, flags);
1152                 drbd_err(device, "drbd_rs_complete_io(,%llu [=%u]) called, "
1153                     "but refcnt is 0!?\n",
1154                     (unsigned long long)sector, enr);
1155                 return;
1156         }
1157
1158         if (lc_put(device->resync, &bm_ext->lce) == 0) {
1159                 bm_ext->flags = 0; /* clear BME_LOCKED, BME_NO_WRITES and BME_PRIORITY */
1160                 device->resync_locked--;
1161                 wake_up(&device->al_wait);
1162         }
1163
1164         spin_unlock_irqrestore(&device->al_lock, flags);
1165 }
1166
1167 /**
1168  * drbd_rs_cancel_all() - Removes all extents from the resync LRU (even BME_LOCKED)
1169  * @device:     DRBD device.
1170  */
1171 void drbd_rs_cancel_all(struct drbd_device *device)
1172 {
1173         spin_lock_irq(&device->al_lock);
1174
1175         if (get_ldev_if_state(device, D_FAILED)) { /* Makes sure ->resync is there. */
1176                 lc_reset(device->resync);
1177                 put_ldev(device);
1178         }
1179         device->resync_locked = 0;
1180         device->resync_wenr = LC_FREE;
1181         spin_unlock_irq(&device->al_lock);
1182         wake_up(&device->al_wait);
1183 }
1184
1185 /**
1186  * drbd_rs_del_all() - Gracefully remove all extents from the resync LRU
1187  * @device:     DRBD device.
1188  *
1189  * Returns 0 upon success, -EAGAIN if at least one reference count was
1190  * not zero.
1191  */
1192 int drbd_rs_del_all(struct drbd_device *device)
1193 {
1194         struct lc_element *e;
1195         struct bm_extent *bm_ext;
1196         int i;
1197
1198         spin_lock_irq(&device->al_lock);
1199
1200         if (get_ldev_if_state(device, D_FAILED)) {
1201                 /* ok, ->resync is there. */
1202                 for (i = 0; i < device->resync->nr_elements; i++) {
1203                         e = lc_element_by_index(device->resync, i);
1204                         bm_ext = lc_entry(e, struct bm_extent, lce);
1205                         if (bm_ext->lce.lc_number == LC_FREE)
1206                                 continue;
1207                         if (bm_ext->lce.lc_number == device->resync_wenr) {
1208                                 drbd_info(device, "dropping %u in drbd_rs_del_all, apparently"
1209                                      " got 'synced' by application io\n",
1210                                      device->resync_wenr);
1211                                 D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1212                                 D_ASSERT(device, test_bit(BME_NO_WRITES, &bm_ext->flags));
1213                                 clear_bit(BME_NO_WRITES, &bm_ext->flags);
1214                                 device->resync_wenr = LC_FREE;
1215                                 lc_put(device->resync, &bm_ext->lce);
1216                         }
1217                         if (bm_ext->lce.refcnt != 0) {
1218                                 drbd_info(device, "Retrying drbd_rs_del_all() later. "
1219                                      "refcnt=%d\n", bm_ext->lce.refcnt);
1220                                 put_ldev(device);
1221                                 spin_unlock_irq(&device->al_lock);
1222                                 return -EAGAIN;
1223                         }
1224                         D_ASSERT(device, !test_bit(BME_LOCKED, &bm_ext->flags));
1225                         D_ASSERT(device, !test_bit(BME_NO_WRITES, &bm_ext->flags));
1226                         lc_del(device->resync, &bm_ext->lce);
1227                 }
1228                 D_ASSERT(device, device->resync->used == 0);
1229                 put_ldev(device);
1230         }
1231         spin_unlock_irq(&device->al_lock);
1232         wake_up(&device->al_wait);
1233
1234         return 0;
1235 }