drivers/mtd/ubi/wl.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (c) International Business Machines Corp., 2006
   4  *
   5  * Authors: Artem Bityutskiy (Битюцкий Артём), Thomas Gleixner
   6  */
   7
   8 /*
   9  * UBI wear-leveling sub-system.
  10  *
  11  * This sub-system is responsible for wear-leveling. It works in terms of
  12  * physical eraseblocks and erase counters and knows nothing about logical
  13  * eraseblocks, volumes, etc. From this sub-system's perspective all physical
  14  * eraseblocks are of two types - used and free. Used physical eraseblocks are
  15  * those that were "get" by the 'ubi_wl_get_peb()' function, and free physical
  16  * eraseblocks are those that were put by the 'ubi_wl_put_peb()' function.
  17  *
  18  * Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter
  19  * header. The rest of the physical eraseblock contains only %0xFF bytes.
  20  *
  21  * When physical eraseblocks are returned to the WL sub-system by means of the
  22  * 'ubi_wl_put_peb()' function, they are scheduled for erasure. The erasure is
  23  * done asynchronously in context of the per-UBI device background thread,
  24  * which is also managed by the WL sub-system.
  25  *
  26  * The wear-leveling is ensured by means of moving the contents of used
  27  * physical eraseblocks with low erase counter to free physical eraseblocks
  28  * with high erase counter.
  29  *
  30  * If the WL sub-system fails to erase a physical eraseblock, it marks it as
  31  * bad.
  32  *
  33  * This sub-system is also responsible for scrubbing. If a bit-flip is detected
  34  * in a physical eraseblock, it has to be moved. Technically this is the same
  35  * as moving it for wear-leveling reasons.
  36  *
  37  * As it was said, for the UBI sub-system all physical eraseblocks are either
  38  * "free" or "used". Free eraseblock are kept in the @wl->free RB-tree, while
  39  * used eraseblocks are kept in @wl->used, @wl->erroneous, or @wl->scrub
  40  * RB-trees, as well as (temporarily) in the @wl->pq queue.
  41  *
  42  * When the WL sub-system returns a physical eraseblock, the physical
  43  * eraseblock is protected from being moved for some "time". For this reason,
  44  * the physical eraseblock is not directly moved from the @wl->free tree to the
  45  * @wl->used tree. There is a protection queue in between where this
  46  * physical eraseblock is temporarily stored (@wl->pq).
  47  *
  48  * All this protection stuff is needed because:
  49  *  o we don't want to move physical eraseblocks just after we have given them
  50  *    to the user; instead, we first want to let users fill them up with data;
  51  *
  52  *  o there is a chance that the user will put the physical eraseblock very
  53  *    soon, so it makes sense not to move it for some time, but wait.
  54  *
  55  * Physical eraseblocks stay protected only for limited time. But the "time" is
  56  * measured in erase cycles in this case. This is implemented with help of the
  57  * protection queue. Eraseblocks are put to the tail of this queue when they
  58  * are returned by the 'ubi_wl_get_peb()', and eraseblocks are removed from the
  59  * head of the queue on each erase operation (for any eraseblock). So the
  60  * length of the queue defines how may (global) erase cycles PEBs are protected.
  61  *
  62  * To put it differently, each physical eraseblock has 2 main states: free and
  63  * used. The former state corresponds to the @wl->free tree. The latter state
  64  * is split up on several sub-states:
  65  * o the WL movement is allowed (@wl->used tree);
  66  * o the WL movement is disallowed (@wl->erroneous) because the PEB is
  67  *   erroneous - e.g., there was a read error;
  68  * o the WL movement is temporarily prohibited (@wl->pq queue);
  69  * o scrubbing is needed (@wl->scrub tree).
  70  *
  71  * Depending on the sub-state, wear-leveling entries of the used physical
  72  * eraseblocks may be kept in one of those structures.
  73  *
  74  * Note, in this implementation, we keep a small in-RAM object for each physical
  75  * eraseblock. This is surely not a scalable solution. But it appears to be good
  76  * enough for moderately large flashes and it is simple. In future, one may
  77  * re-work this sub-system and make it more scalable.
  78  *
  79  * At the moment this sub-system does not utilize the sequence number, which
  80  * was introduced relatively recently. But it would be wise to do this because
  81  * the sequence number of a logical eraseblock characterizes how old is it. For
  82  * example, when we move a PEB with low erase counter, and we need to pick the
  83  * target PEB, we pick a PEB with the highest EC if our PEB is "old" and we
  84  * pick target PEB with an average EC if our PEB is not very "old". This is a
  85  * room for future re-works of the WL sub-system.
  86  */
  87
  88 #include <linux/slab.h>
  89 #include <linux/crc32.h>
  90 #include <linux/freezer.h>
  91 #include <linux/kthread.h>
  92 #include "ubi.h"
  93 #include "wl.h"
  94
  95 /* Number of physical eraseblocks reserved for wear-leveling purposes */
  96 #define WL_RESERVED_PEBS 1
  97
  98 /*
  99  * Maximum difference between two erase counters. If this threshold is
 100  * exceeded, the WL sub-system starts moving data from used physical
 101  * eraseblocks with low erase counter to free physical eraseblocks with high
 102  * erase counter.
 103  */
 104 #define UBI_WL_THRESHOLD CONFIG_MTD_UBI_WL_THRESHOLD
 105
 106 /*
 107  * When a physical eraseblock is moved, the WL sub-system has to pick the target
 108  * physical eraseblock to move to. The simplest way would be just to pick the
 109  * one with the highest erase counter. But in certain workloads this could lead
 110  * to an unlimited wear of one or few physical eraseblock. Indeed, imagine a
 111  * situation when the picked physical eraseblock is constantly erased after the
 112  * data is written to it. So, we have a constant which limits the highest erase
 113  * counter of the free physical eraseblock to pick. Namely, the WL sub-system
 114  * does not pick eraseblocks with erase counter greater than the lowest erase
 115  * counter plus %WL_FREE_MAX_DIFF.
 116  */
 117 #define WL_FREE_MAX_DIFF (2*UBI_WL_THRESHOLD)
 118
 119 /*
 120  * Maximum number of consecutive background thread failures which is enough to
 121  * switch to read-only mode.
 122  */
 123 #define WL_MAX_FAILURES 32
 124
 125 static int self_check_ec(struct ubi_device *ubi, int pnum, int ec);
 126 static int self_check_in_wl_tree(const struct ubi_device *ubi,
 127                                  struct ubi_wl_entry *e, struct rb_root *root);
 128 static int self_check_in_pq(const struct ubi_device *ubi,
 129                             struct ubi_wl_entry *e);
 130
 131 /**
 132  * wl_tree_add - add a wear-leveling entry to a WL RB-tree.
 133  * @e: the wear-leveling entry to add
 134  * @root: the root of the tree
 135  *
 136  * Note, we use (erase counter, physical eraseblock number) pairs as keys in
 137  * the @ubi->used and @ubi->free RB-trees.
 138  */
 139 static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
 140 {
 141         struct rb_node **p, *parent = NULL;
 142
 143         p = &root->rb_node;
 144         while (*p) {
 145                 struct ubi_wl_entry *e1;
 146
 147                 parent = *p;
 148                 e1 = rb_entry(parent, struct ubi_wl_entry, u.rb);
 149
 150                 if (e->ec < e1->ec)
 151                         p = &(*p)->rb_left;
 152                 else if (e->ec > e1->ec)
 153                         p = &(*p)->rb_right;
 154                 else {
 155                         ubi_assert(e->pnum != e1->pnum);
 156                         if (e->pnum < e1->pnum)
 157                                 p = &(*p)->rb_left;
 158                         else
 159                                 p = &(*p)->rb_right;
 160                 }
 161         }
 162
 163         rb_link_node(&e->u.rb, parent, p);
 164         rb_insert_color(&e->u.rb, root);
 165 }
 166
 167 /**
 168  * wl_tree_destroy - destroy a wear-leveling entry.
 169  * @ubi: UBI device description object
 170  * @e: the wear-leveling entry to add
 171  *
 172  * This function destroys a wear leveling entry and removes
 173  * the reference from the lookup table.
 174  */
 175 static void wl_entry_destroy(struct ubi_device *ubi, struct ubi_wl_entry *e)
 176 {
 177         ubi->lookuptbl[e->pnum] = NULL;
 178         kmem_cache_free(ubi_wl_entry_slab, e);
 179 }
 180
 181 /**
 182  * do_work - do one pending work.
 183  * @ubi: UBI device description object
 184  *
 185  * This function returns zero in case of success and a negative error code in
 186  * case of failure.
 187  */
 188 static int do_work(struct ubi_device *ubi)
 189 {
 190         int err;
 191         struct ubi_work *wrk;
 192
 193         cond_resched();
 194
 195         /*
 196          * @ubi->work_sem is used to synchronize with the workers. Workers take
 197          * it in read mode, so many of them may be doing works at a time. But
 198          * the queue flush code has to be sure the whole queue of works is
 199          * done, and it takes the mutex in write mode.
 200          */
 201         down_read(&ubi->work_sem);
 202         spin_lock(&ubi->wl_lock);
 203         if (list_empty(&ubi->works)) {
 204                 spin_unlock(&ubi->wl_lock);
 205                 up_read(&ubi->work_sem);
 206                 return 0;
 207         }
 208
 209         wrk = list_entry(ubi->works.next, struct ubi_work, list);
 210         list_del(&wrk->list);
 211         ubi->works_count -= 1;
 212         ubi_assert(ubi->works_count >= 0);
 213         spin_unlock(&ubi->wl_lock);
 214
 215         /*
 216          * Call the worker function. Do not touch the work structure
 217          * after this call as it will have been freed or reused by that
 218          * time by the worker function.
 219          */
 220         err = wrk->func(ubi, wrk, 0);
 221         if (err)
 222                 ubi_err(ubi, "work failed with error code %d", err);
 223         up_read(&ubi->work_sem);
 224
 225         return err;
 226 }
 227
 228 /**
 229  * in_wl_tree - check if wear-leveling entry is present in a WL RB-tree.
 230  * @e: the wear-leveling entry to check
 231  * @root: the root of the tree
 232  *
 233  * This function returns non-zero if @e is in the @root RB-tree and zero if it
 234  * is not.
 235  */
 236 static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
 237 {
 238         struct rb_node *p;
 239
 240         p = root->rb_node;
 241         while (p) {
 242                 struct ubi_wl_entry *e1;
 243
 244                 e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
 245
 246                 if (e->pnum == e1->pnum) {
 247                         ubi_assert(e == e1);
 248                         return 1;
 249                 }
 250
 251                 if (e->ec < e1->ec)
 252                         p = p->rb_left;
 253                 else if (e->ec > e1->ec)
 254                         p = p->rb_right;
 255                 else {
 256                         ubi_assert(e->pnum != e1->pnum);
 257                         if (e->pnum < e1->pnum)
 258                                 p = p->rb_left;
 259                         else
 260                                 p = p->rb_right;
 261                 }
 262         }
 263
 264         return 0;
 265 }
 266
 267 /**
 268  * in_pq - check if a wear-leveling entry is present in the protection queue.
 269  * @ubi: UBI device description object
 270  * @e: the wear-leveling entry to check
 271  *
 272  * This function returns non-zero if @e is in the protection queue and zero
 273  * if it is not.
 274  */
 275 static inline int in_pq(const struct ubi_device *ubi, struct ubi_wl_entry *e)
 276 {
 277         struct ubi_wl_entry *p;
 278         int i;
 279
 280         for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i)
 281                 list_for_each_entry(p, &ubi->pq[i], u.list)
 282                         if (p == e)
 283                                 return 1;
 284
 285         return 0;
 286 }
 287
 288 /**
 289  * prot_queue_add - add physical eraseblock to the protection queue.
 290  * @ubi: UBI device description object
 291  * @e: the physical eraseblock to add
 292  *
 293  * This function adds @e to the tail of the protection queue @ubi->pq, where
 294  * @e will stay for %UBI_PROT_QUEUE_LEN erase operations and will be
 295  * temporarily protected from the wear-leveling worker. Note, @wl->lock has to
 296  * be locked.
 297  */
 298 static void prot_queue_add(struct ubi_device *ubi, struct ubi_wl_entry *e)
 299 {
 300         int pq_tail = ubi->pq_head - 1;
 301
 302         if (pq_tail < 0)
 303                 pq_tail = UBI_PROT_QUEUE_LEN - 1;
 304         ubi_assert(pq_tail >= 0 && pq_tail < UBI_PROT_QUEUE_LEN);
 305         list_add_tail(&e->u.list, &ubi->pq[pq_tail]);
 306         dbg_wl("added PEB %d EC %d to the protection queue", e->pnum, e->ec);
 307 }
 308
 309 /**
 310  * find_wl_entry - find wear-leveling entry closest to certain erase counter.
 311  * @ubi: UBI device description object
 312  * @root: the RB-tree where to look for
 313  * @diff: maximum possible difference from the smallest erase counter
 314  *
 315  * This function looks for a wear leveling entry with erase counter closest to
 316  * min + @diff, where min is the smallest erase counter.
 317  */
 318 static struct ubi_wl_entry *find_wl_entry(struct ubi_device *ubi,
 319                                           struct rb_root *root, int diff)
 320 {
 321         struct rb_node *p;
 322         struct ubi_wl_entry *e;
 323         int max;
 324
 325         e = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
 326         max = e->ec + diff;
 327
 328         p = root->rb_node;
 329         while (p) {
 330                 struct ubi_wl_entry *e1;
 331
 332                 e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
 333                 if (e1->ec >= max)
 334                         p = p->rb_left;
 335                 else {
 336                         p = p->rb_right;
 337                         e = e1;
 338                 }
 339         }
 340
 341         return e;
 342 }
 343
 344 /**
 345  * find_mean_wl_entry - find wear-leveling entry with medium erase counter.
 346  * @ubi: UBI device description object
 347  * @root: the RB-tree where to look for
 348  *
 349  * This function looks for a wear leveling entry with medium erase counter,
 350  * but not greater or equivalent than the lowest erase counter plus
 351  * %WL_FREE_MAX_DIFF/2.
 352  */
 353 static struct ubi_wl_entry *find_mean_wl_entry(struct ubi_device *ubi,
 354                                                struct rb_root *root)
 355 {
 356         struct ubi_wl_entry *e, *first, *last;
 357
 358         first = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
 359         last = rb_entry(rb_last(root), struct ubi_wl_entry, u.rb);
 360
 361         if (last->ec - first->ec < WL_FREE_MAX_DIFF) {
 362                 e = rb_entry(root->rb_node, struct ubi_wl_entry, u.rb);
 363
 364                 /* If no fastmap has been written and this WL entry can be used
 365                  * as anchor PEB, hold it back and return the second best
 366                  * WL entry such that fastmap can use the anchor PEB later. */
 367                 e = may_reserve_for_fm(ubi, e, root);
 368         } else
 369                 e = find_wl_entry(ubi, root, WL_FREE_MAX_DIFF/2);
 370
 371         return e;
 372 }
 373
 374 /**
 375  * wl_get_wle - get a mean wl entry to be used by ubi_wl_get_peb() or
 376  * refill_wl_user_pool().
 377  * @ubi: UBI device description object
 378  *
 379  * This function returns a a wear leveling entry in case of success and
 380  * NULL in case of failure.
 381  */
 382 static struct ubi_wl_entry *wl_get_wle(struct ubi_device *ubi)
 383 {
 384         struct ubi_wl_entry *e;
 385
 386         e = find_mean_wl_entry(ubi, &ubi->free);
 387         if (!e) {
 388                 ubi_err(ubi, "no free eraseblocks");
 389                 return NULL;
 390         }
 391
 392         self_check_in_wl_tree(ubi, e, &ubi->free);
 393
 394         /*
 395          * Move the physical eraseblock to the protection queue where it will
 396          * be protected from being moved for some time.
 397          */
 398         rb_erase(&e->u.rb, &ubi->free);
 399         ubi->free_count--;
 400         dbg_wl("PEB %d EC %d", e->pnum, e->ec);
 401
 402         return e;
 403 }
 404
 405 /**
 406  * prot_queue_del - remove a physical eraseblock from the protection queue.
 407  * @ubi: UBI device description object
 408  * @pnum: the physical eraseblock to remove
 409  *
 410  * This function deletes PEB @pnum from the protection queue and returns zero
 411  * in case of success and %-ENODEV if the PEB was not found.
 412  */
 413 static int prot_queue_del(struct ubi_device *ubi, int pnum)
 414 {
 415         struct ubi_wl_entry *e;
 416
 417         e = ubi->lookuptbl[pnum];
 418         if (!e)
 419                 return -ENODEV;
 420
 421         if (self_check_in_pq(ubi, e))
 422                 return -ENODEV;
 423
 424         list_del(&e->u.list);
 425         dbg_wl("deleted PEB %d from the protection queue", e->pnum);
 426         return 0;
 427 }
 428
 429 /**
 430  * sync_erase - synchronously erase a physical eraseblock.
 431  * @ubi: UBI device description object
 432  * @e: the the physical eraseblock to erase
 433  * @torture: if the physical eraseblock has to be tortured
 434  *
 435  * This function returns zero in case of success and a negative error code in
 436  * case of failure.
 437  */
 438 static int sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 439                       int torture)
 440 {
 441         int err;
 442         struct ubi_ec_hdr *ec_hdr;
 443         unsigned long long ec = e->ec;
 444
 445         dbg_wl("erase PEB %d, old EC %llu", e->pnum, ec);
 446
 447         err = self_check_ec(ubi, e->pnum, e->ec);
 448         if (err)
 449                 return -EINVAL;
 450
 451         ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
 452         if (!ec_hdr)
 453                 return -ENOMEM;
 454
 455         err = ubi_io_sync_erase(ubi, e->pnum, torture);
 456         if (err < 0)
 457                 goto out_free;
 458
 459         ec += err;
 460         if (ec > UBI_MAX_ERASECOUNTER) {
 461                 /*
 462                  * Erase counter overflow. Upgrade UBI and use 64-bit
 463                  * erase counters internally.
 464                  */
 465                 ubi_err(ubi, "erase counter overflow at PEB %d, EC %llu",
 466                         e->pnum, ec);
 467                 err = -EINVAL;
 468                 goto out_free;
 469         }
 470
 471         dbg_wl("erased PEB %d, new EC %llu", e->pnum, ec);
 472
 473         ec_hdr->ec = cpu_to_be64(ec);
 474
 475         err = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr);
 476         if (err)
 477                 goto out_free;
 478
 479         e->ec = ec;
 480         spin_lock(&ubi->wl_lock);
 481         if (e->ec > ubi->max_ec)
 482                 ubi->max_ec = e->ec;
 483         spin_unlock(&ubi->wl_lock);
 484
 485 out_free:
 486         kfree(ec_hdr);
 487         return err;
 488 }
 489
 490 /**
 491  * serve_prot_queue - check if it is time to stop protecting PEBs.
 492  * @ubi: UBI device description object
 493  *
 494  * This function is called after each erase operation and removes PEBs from the
 495  * tail of the protection queue. These PEBs have been protected for long enough
 496  * and should be moved to the used tree.
 497  */
 498 static void serve_prot_queue(struct ubi_device *ubi)
 499 {
 500         struct ubi_wl_entry *e, *tmp;
 501         int count;
 502
 503         /*
 504          * There may be several protected physical eraseblock to remove,
 505          * process them all.
 506          */
 507 repeat:
 508         count = 0;
 509         spin_lock(&ubi->wl_lock);
 510         list_for_each_entry_safe(e, tmp, &ubi->pq[ubi->pq_head], u.list) {
 511                 dbg_wl("PEB %d EC %d protection over, move to used tree",
 512                         e->pnum, e->ec);
 513
 514                 list_del(&e->u.list);
 515                 wl_tree_add(e, &ubi->used);
 516                 if (count++ > 32) {
 517                         /*
 518                          * Let's be nice and avoid holding the spinlock for
 519                          * too long.
 520                          */
 521                         spin_unlock(&ubi->wl_lock);
 522                         cond_resched();
 523                         goto repeat;
 524                 }
 525         }
 526
 527         ubi->pq_head += 1;
 528         if (ubi->pq_head == UBI_PROT_QUEUE_LEN)
 529                 ubi->pq_head = 0;
 530         ubi_assert(ubi->pq_head >= 0 && ubi->pq_head < UBI_PROT_QUEUE_LEN);
 531         spin_unlock(&ubi->wl_lock);
 532 }
 533
 534 /**
 535  * __schedule_ubi_work - schedule a work.
 536  * @ubi: UBI device description object
 537  * @wrk: the work to schedule
 538  *
 539  * This function adds a work defined by @wrk to the tail of the pending works
 540  * list. Can only be used if ubi->work_sem is already held in read mode!
 541  */
 542 static void __schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
 543 {
 544         spin_lock(&ubi->wl_lock);
 545         list_add_tail(&wrk->list, &ubi->works);
 546         ubi_assert(ubi->works_count >= 0);
 547         ubi->works_count += 1;
 548         if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled(ubi))
 549                 wake_up_process(ubi->bgt_thread);
 550         spin_unlock(&ubi->wl_lock);
 551 }
 552
 553 /**
 554  * schedule_ubi_work - schedule a work.
 555  * @ubi: UBI device description object
 556  * @wrk: the work to schedule
 557  *
 558  * This function adds a work defined by @wrk to the tail of the pending works
 559  * list.
 560  */
 561 static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
 562 {
 563         down_read(&ubi->work_sem);
 564         __schedule_ubi_work(ubi, wrk);
 565         up_read(&ubi->work_sem);
 566 }
 567
 568 static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 569                         int shutdown);
 570
 571 /**
 572  * schedule_erase - schedule an erase work.
 573  * @ubi: UBI device description object
 574  * @e: the WL entry of the physical eraseblock to erase
 575  * @vol_id: the volume ID that last used this PEB
 576  * @lnum: the last used logical eraseblock number for the PEB
 577  * @torture: if the physical eraseblock has to be tortured
 578  * @nested: denotes whether the work_sem is already held in read mode
 579  *
 580  * This function returns zero in case of success and a %-ENOMEM in case of
 581  * failure.
 582  */
 583 static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 584                           int vol_id, int lnum, int torture, bool nested)
 585 {
 586         struct ubi_work *wl_wrk;
 587
 588         ubi_assert(e);
 589
 590         dbg_wl("schedule erasure of PEB %d, EC %d, torture %d",
 591                e->pnum, e->ec, torture);
 592
 593         wl_wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
 594         if (!wl_wrk)
 595                 return -ENOMEM;
 596
 597         wl_wrk->func = &erase_worker;
 598         wl_wrk->e = e;
 599         wl_wrk->vol_id = vol_id;
 600         wl_wrk->lnum = lnum;
 601         wl_wrk->torture = torture;
 602
 603         if (nested)
 604                 __schedule_ubi_work(ubi, wl_wrk);
 605         else
 606                 schedule_ubi_work(ubi, wl_wrk);
 607         return 0;
 608 }
 609
 610 static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk);
 611 /**
 612  * do_sync_erase - run the erase worker synchronously.
 613  * @ubi: UBI device description object
 614  * @e: the WL entry of the physical eraseblock to erase
 615  * @vol_id: the volume ID that last used this PEB
 616  * @lnum: the last used logical eraseblock number for the PEB
 617  * @torture: if the physical eraseblock has to be tortured
 618  *
 619  */
 620 static int do_sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 621                          int vol_id, int lnum, int torture)
 622 {
 623         struct ubi_work wl_wrk;
 624
 625         dbg_wl("sync erase of PEB %i", e->pnum);
 626
 627         wl_wrk.e = e;
 628         wl_wrk.vol_id = vol_id;
 629         wl_wrk.lnum = lnum;
 630         wl_wrk.torture = torture;
 631
 632         return __erase_worker(ubi, &wl_wrk);
 633 }
 634
 635 static int ensure_wear_leveling(struct ubi_device *ubi, int nested);
 636 /**
 637  * wear_leveling_worker - wear-leveling worker function.
 638  * @ubi: UBI device description object
 639  * @wrk: the work object
 640  * @shutdown: non-zero if the worker has to free memory and exit
 641  * because the WL-subsystem is shutting down
 642  *
 643  * This function copies a more worn out physical eraseblock to a less worn out
 644  * one. Returns zero in case of success and a negative error code in case of
 645  * failure.
 646  */
 647 static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
 648                                 int shutdown)
 649 {
 650         int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
 651         int erase = 0, keep = 0, vol_id = -1, lnum = -1;
 652         struct ubi_wl_entry *e1, *e2;
 653         struct ubi_vid_io_buf *vidb;
 654         struct ubi_vid_hdr *vid_hdr;
 655         int dst_leb_clean = 0;
 656
 657         kfree(wrk);
 658         if (shutdown)
 659                 return 0;
 660
 661         vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
 662         if (!vidb)
 663                 return -ENOMEM;
 664
 665         vid_hdr = ubi_get_vid_hdr(vidb);
 666
 667         down_read(&ubi->fm_eba_sem);
 668         mutex_lock(&ubi->move_mutex);
 669         spin_lock(&ubi->wl_lock);
 670         ubi_assert(!ubi->move_from && !ubi->move_to);
 671         ubi_assert(!ubi->move_to_put);
 672
 673         if (!ubi->free.rb_node ||
 674             (!ubi->used.rb_node && !ubi->scrub.rb_node)) {
 675                 /*
 676                  * No free physical eraseblocks? Well, they must be waiting in
 677                  * the queue to be erased. Cancel movement - it will be
 678                  * triggered again when a free physical eraseblock appears.
 679                  *
 680                  * No used physical eraseblocks? They must be temporarily
 681                  * protected from being moved. They will be moved to the
 682                  * @ubi->used tree later and the wear-leveling will be
 683                  * triggered again.
 684                  */
 685                 dbg_wl("cancel WL, a list is empty: free %d, used %d",
 686                        !ubi->free.rb_node, !ubi->used.rb_node);
 687                 goto out_cancel;
 688         }
 689
 690 #ifdef CONFIG_MTD_UBI_FASTMAP
 691         e1 = find_anchor_wl_entry(&ubi->used);
 692         if (e1 && ubi->fm_anchor &&
 693             (ubi->fm_anchor->ec - e1->ec >= UBI_WL_THRESHOLD)) {
 694                 ubi->fm_do_produce_anchor = 1;
 695                 /*
 696                  * fm_anchor is no longer considered a good anchor.
 697                  * NULL assignment also prevents multiple wear level checks
 698                  * of this PEB.
 699                  */
 700                 wl_tree_add(ubi->fm_anchor, &ubi->free);
 701                 ubi->fm_anchor = NULL;
 702                 ubi->free_count++;
 703         }
 704
 705         if (ubi->fm_do_produce_anchor) {
 706                 if (!e1)
 707                         goto out_cancel;
 708                 e2 = get_peb_for_wl(ubi);
 709                 if (!e2)
 710                         goto out_cancel;
 711
 712                 self_check_in_wl_tree(ubi, e1, &ubi->used);
 713                 rb_erase(&e1->u.rb, &ubi->used);
 714                 dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
 715                 ubi->fm_do_produce_anchor = 0;
 716         } else if (!ubi->scrub.rb_node) {
 717 #else
 718         if (!ubi->scrub.rb_node) {
 719 #endif
 720                 /*
 721                  * Now pick the least worn-out used physical eraseblock and a
 722                  * highly worn-out free physical eraseblock. If the erase
 723                  * counters differ much enough, start wear-leveling.
 724                  */
 725                 e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
 726                 e2 = get_peb_for_wl(ubi);
 727                 if (!e2)
 728                         goto out_cancel;
 729
 730                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) {
 731                         dbg_wl("no WL needed: min used EC %d, max free EC %d",
 732                                e1->ec, e2->ec);
 733
 734                         /* Give the unused PEB back */
 735                         wl_tree_add(e2, &ubi->free);
 736                         ubi->free_count++;
 737                         goto out_cancel;
 738                 }
 739                 self_check_in_wl_tree(ubi, e1, &ubi->used);
 740                 rb_erase(&e1->u.rb, &ubi->used);
 741                 dbg_wl("move PEB %d EC %d to PEB %d EC %d",
 742                        e1->pnum, e1->ec, e2->pnum, e2->ec);
 743         } else {
 744                 /* Perform scrubbing */
 745                 scrubbing = 1;
 746                 e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
 747                 e2 = get_peb_for_wl(ubi);
 748                 if (!e2)
 749                         goto out_cancel;
 750
 751                 self_check_in_wl_tree(ubi, e1, &ubi->scrub);
 752                 rb_erase(&e1->u.rb, &ubi->scrub);
 753                 dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
 754         }
 755
 756         ubi->move_from = e1;
 757         ubi->move_to = e2;
 758         spin_unlock(&ubi->wl_lock);
 759
 760         /*
 761          * Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum.
 762          * We so far do not know which logical eraseblock our physical
 763          * eraseblock (@e1) belongs to. We have to read the volume identifier
 764          * header first.
 765          *
 766          * Note, we are protected from this PEB being unmapped and erased. The
 767          * 'ubi_wl_put_peb()' would wait for moving to be finished if the PEB
 768          * which is being moved was unmapped.
 769          */
 770
 771         err = ubi_io_read_vid_hdr(ubi, e1->pnum, vidb, 0);
 772         if (err && err != UBI_IO_BITFLIPS) {
 773                 dst_leb_clean = 1;
 774                 if (err == UBI_IO_FF) {
 775                         /*
 776                          * We are trying to move PEB without a VID header. UBI
 777                          * always write VID headers shortly after the PEB was
 778                          * given, so we have a situation when it has not yet
 779                          * had a chance to write it, because it was preempted.
 780                          * So add this PEB to the protection queue so far,
 781                          * because presumably more data will be written there
 782                          * (including the missing VID header), and then we'll
 783                          * move it.
 784                          */
 785                         dbg_wl("PEB %d has no VID header", e1->pnum);
 786                         protect = 1;
 787                         goto out_not_moved;
 788                 } else if (err == UBI_IO_FF_BITFLIPS) {
 789                         /*
 790                          * The same situation as %UBI_IO_FF, but bit-flips were
 791                          * detected. It is better to schedule this PEB for
 792                          * scrubbing.
 793                          */
 794                         dbg_wl("PEB %d has no VID header but has bit-flips",
 795                                e1->pnum);
 796                         scrubbing = 1;
 797                         goto out_not_moved;
 798                 } else if (ubi->fast_attach && err == UBI_IO_BAD_HDR_EBADMSG) {
 799                         /*
 800                          * While a full scan would detect interrupted erasures
 801                          * at attach time we can face them here when attached from
 802                          * Fastmap.
 803                          */
 804                         dbg_wl("PEB %d has ECC errors, maybe from an interrupted erasure",
 805                                e1->pnum);
 806                         erase = 1;
 807                         goto out_not_moved;
 808                 }
 809
 810                 ubi_err(ubi, "error %d while reading VID header from PEB %d",
 811                         err, e1->pnum);
 812                 goto out_error;
 813         }
 814
 815         vol_id = be32_to_cpu(vid_hdr->vol_id);
 816         lnum = be32_to_cpu(vid_hdr->lnum);
 817
 818         err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vidb);
 819         if (err) {
 820                 if (err == MOVE_CANCEL_RACE) {
 821                         /*
 822                          * The LEB has not been moved because the volume is
 823                          * being deleted or the PEB has been put meanwhile. We
 824                          * should prevent this PEB from being selected for
 825                          * wear-leveling movement again, so put it to the
 826                          * protection queue.
 827                          */
 828                         protect = 1;
 829                         dst_leb_clean = 1;
 830                         goto out_not_moved;
 831                 }
 832                 if (err == MOVE_RETRY) {
 833                         scrubbing = 1;
 834                         dst_leb_clean = 1;
 835                         goto out_not_moved;
 836                 }
 837                 if (err == MOVE_TARGET_BITFLIPS || err == MOVE_TARGET_WR_ERR ||
 838                     err == MOVE_TARGET_RD_ERR) {
 839                         /*
 840                          * Target PEB had bit-flips or write error - torture it.
 841                          */
 842                         torture = 1;
 843                         keep = 1;
 844                         goto out_not_moved;
 845                 }
 846
 847                 if (err == MOVE_SOURCE_RD_ERR) {
 848                         /*
 849                          * An error happened while reading the source PEB. Do
 850                          * not switch to R/O mode in this case, and give the
 851                          * upper layers a possibility to recover from this,
 852                          * e.g. by unmapping corresponding LEB. Instead, just
 853                          * put this PEB to the @ubi->erroneous list to prevent
 854                          * UBI from trying to move it over and over again.
 855                          */
 856                         if (ubi->erroneous_peb_count > ubi->max_erroneous) {
 857                                 ubi_err(ubi, "too many erroneous eraseblocks (%d)",
 858                                         ubi->erroneous_peb_count);
 859                                 goto out_error;
 860                         }
 861                         dst_leb_clean = 1;
 862                         erroneous = 1;
 863                         goto out_not_moved;
 864                 }
 865
 866                 if (err < 0)
 867                         goto out_error;
 868
 869                 ubi_assert(0);
 870         }
 871
 872         /* The PEB has been successfully moved */
 873         if (scrubbing)
 874                 ubi_msg(ubi, "scrubbed PEB %d (LEB %d:%d), data moved to PEB %d",
 875                         e1->pnum, vol_id, lnum, e2->pnum);
 876         ubi_free_vid_buf(vidb);
 877
 878         spin_lock(&ubi->wl_lock);
 879         if (!ubi->move_to_put) {
 880                 wl_tree_add(e2, &ubi->used);
 881                 e2 = NULL;
 882         }
 883         ubi->move_from = ubi->move_to = NULL;
 884         ubi->move_to_put = ubi->wl_scheduled = 0;
 885         spin_unlock(&ubi->wl_lock);
 886
 887         err = do_sync_erase(ubi, e1, vol_id, lnum, 0);
 888         if (err) {
 889                 if (e2)
 890                         wl_entry_destroy(ubi, e2);
 891                 goto out_ro;
 892         }
 893
 894         if (e2) {
 895                 /*
 896                  * Well, the target PEB was put meanwhile, schedule it for
 897                  * erasure.
 898                  */
 899                 dbg_wl("PEB %d (LEB %d:%d) was put meanwhile, erase",
 900                        e2->pnum, vol_id, lnum);
 901                 err = do_sync_erase(ubi, e2, vol_id, lnum, 0);
 902                 if (err)
 903                         goto out_ro;
 904         }
 905
 906         dbg_wl("done");
 907         mutex_unlock(&ubi->move_mutex);
 908         up_read(&ubi->fm_eba_sem);
 909         return 0;
 910
 911         /*
 912          * For some reasons the LEB was not moved, might be an error, might be
 913          * something else. @e1 was not changed, so return it back. @e2 might
 914          * have been changed, schedule it for erasure.
 915          */
 916 out_not_moved:
 917         if (vol_id != -1)
 918                 dbg_wl("cancel moving PEB %d (LEB %d:%d) to PEB %d (%d)",
 919                        e1->pnum, vol_id, lnum, e2->pnum, err);
 920         else
 921                 dbg_wl("cancel moving PEB %d to PEB %d (%d)",
 922                        e1->pnum, e2->pnum, err);
 923         spin_lock(&ubi->wl_lock);
 924         if (protect)
 925                 prot_queue_add(ubi, e1);
 926         else if (erroneous) {
 927                 wl_tree_add(e1, &ubi->erroneous);
 928                 ubi->erroneous_peb_count += 1;
 929         } else if (scrubbing)
 930                 wl_tree_add(e1, &ubi->scrub);
 931         else if (keep)
 932                 wl_tree_add(e1, &ubi->used);
 933         if (dst_leb_clean) {
 934                 wl_tree_add(e2, &ubi->free);
 935                 ubi->free_count++;
 936         }
 937
 938         ubi_assert(!ubi->move_to_put);
 939         ubi->move_from = ubi->move_to = NULL;
 940         ubi->wl_scheduled = 0;
 941         spin_unlock(&ubi->wl_lock);
 942
 943         ubi_free_vid_buf(vidb);
 944         if (dst_leb_clean) {
 945                 ensure_wear_leveling(ubi, 1);
 946         } else {
 947                 err = do_sync_erase(ubi, e2, vol_id, lnum, torture);
 948                 if (err)
 949                         goto out_ro;
 950         }
 951
 952         if (erase) {
 953                 err = do_sync_erase(ubi, e1, vol_id, lnum, 1);
 954                 if (err)
 955                         goto out_ro;
 956         }
 957
 958         mutex_unlock(&ubi->move_mutex);
 959         up_read(&ubi->fm_eba_sem);
 960         return 0;
 961
 962 out_error:
 963         if (vol_id != -1)
 964                 ubi_err(ubi, "error %d while moving PEB %d to PEB %d",
 965                         err, e1->pnum, e2->pnum);
 966         else
 967                 ubi_err(ubi, "error %d while moving PEB %d (LEB %d:%d) to PEB %d",
 968                         err, e1->pnum, vol_id, lnum, e2->pnum);
 969         spin_lock(&ubi->wl_lock);
 970         ubi->move_from = ubi->move_to = NULL;
 971         ubi->move_to_put = ubi->wl_scheduled = 0;
 972         spin_unlock(&ubi->wl_lock);
 973
 974         ubi_free_vid_buf(vidb);
 975         wl_entry_destroy(ubi, e1);
 976         wl_entry_destroy(ubi, e2);
 977
 978 out_ro:
 979         ubi_ro_mode(ubi);
 980         mutex_unlock(&ubi->move_mutex);
 981         up_read(&ubi->fm_eba_sem);
 982         ubi_assert(err != 0);
 983         return err < 0 ? err : -EIO;
 984
 985 out_cancel:
 986         ubi->wl_scheduled = 0;
 987         spin_unlock(&ubi->wl_lock);
 988         mutex_unlock(&ubi->move_mutex);
 989         up_read(&ubi->fm_eba_sem);
 990         ubi_free_vid_buf(vidb);
 991         return 0;
 992 }
 993
 994 /**
 995  * ensure_wear_leveling - schedule wear-leveling if it is needed.
 996  * @ubi: UBI device description object
 997  * @nested: set to non-zero if this function is called from UBI worker
 998  *
 999  * This function checks if it is time to start wear-leveling and schedules it
1000  * if yes. This function returns zero in case of success and a negative error
1001  * code in case of failure.
1002  */
1003 static int ensure_wear_leveling(struct ubi_device *ubi, int nested)
1004 {
1005         int err = 0;
1006         struct ubi_wl_entry *e1;
1007         struct ubi_wl_entry *e2;
1008         struct ubi_work *wrk;
1009
1010         spin_lock(&ubi->wl_lock);
1011         if (ubi->wl_scheduled)
1012                 /* Wear-leveling is already in the work queue */
1013                 goto out_unlock;
1014
1015         /*
1016          * If the ubi->scrub tree is not empty, scrubbing is needed, and the
1017          * the WL worker has to be scheduled anyway.
1018          */
1019         if (!ubi->scrub.rb_node) {
1020                 if (!ubi->used.rb_node || !ubi->free.rb_node)
1021                         /* No physical eraseblocks - no deal */
1022                         goto out_unlock;
1023
1024                 /*
1025                  * We schedule wear-leveling only if the difference between the
1026                  * lowest erase counter of used physical eraseblocks and a high
1027                  * erase counter of free physical eraseblocks is greater than
1028                  * %UBI_WL_THRESHOLD.
1029                  */
1030                 e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
1031                 e2 = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
1032
1033                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD))
1034                         goto out_unlock;
1035                 dbg_wl("schedule wear-leveling");
1036         } else
1037                 dbg_wl("schedule scrubbing");
1038
1039         ubi->wl_scheduled = 1;
1040         spin_unlock(&ubi->wl_lock);
1041
1042         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
1043         if (!wrk) {
1044                 err = -ENOMEM;
1045                 goto out_cancel;
1046         }
1047
1048         wrk->func = &wear_leveling_worker;
1049         if (nested)
1050                 __schedule_ubi_work(ubi, wrk);
1051         else
1052                 schedule_ubi_work(ubi, wrk);
1053         return err;
1054
1055 out_cancel:
1056         spin_lock(&ubi->wl_lock);
1057         ubi->wl_scheduled = 0;
1058 out_unlock:
1059         spin_unlock(&ubi->wl_lock);
1060         return err;
1061 }
1062
1063 /**
1064  * __erase_worker - physical eraseblock erase worker function.
1065  * @ubi: UBI device description object
1066  * @wl_wrk: the work object
1067  *
1068  * This function erases a physical eraseblock and perform torture testing if
1069  * needed. It also takes care about marking the physical eraseblock bad if
1070  * needed. Returns zero in case of success and a negative error code in case of
1071  * failure.
1072  */
1073 static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
1074 {
1075         struct ubi_wl_entry *e = wl_wrk->e;
1076         int pnum = e->pnum;
1077         int vol_id = wl_wrk->vol_id;
1078         int lnum = wl_wrk->lnum;
1079         int err, available_consumed = 0;
1080
1081         dbg_wl("erase PEB %d EC %d LEB %d:%d",
1082                pnum, e->ec, wl_wrk->vol_id, wl_wrk->lnum);
1083
1084         err = sync_erase(ubi, e, wl_wrk->torture);
1085         if (!err) {
1086                 spin_lock(&ubi->wl_lock);
1087
1088                 if (!ubi->fm_disabled && !ubi->fm_anchor &&
1089                     e->pnum < UBI_FM_MAX_START) {
1090                         /*
1091                          * Abort anchor production, if needed it will be
1092                          * enabled again in the wear leveling started below.
1093                          */
1094                         ubi->fm_anchor = e;
1095                         ubi->fm_do_produce_anchor = 0;
1096                 } else {
1097                         wl_tree_add(e, &ubi->free);
1098                         ubi->free_count++;
1099                 }
1100
1101                 spin_unlock(&ubi->wl_lock);
1102
1103                 /*
1104                  * One more erase operation has happened, take care about
1105                  * protected physical eraseblocks.
1106                  */
1107                 serve_prot_queue(ubi);
1108
1109                 /* And take care about wear-leveling */
1110                 err = ensure_wear_leveling(ubi, 1);
1111                 return err;
1112         }
1113
1114         ubi_err(ubi, "failed to erase PEB %d, error %d", pnum, err);
1115
1116         if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
1117             err == -EBUSY) {
1118                 int err1;
1119
1120                 /* Re-schedule the LEB for erasure */
1121                 err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false);
1122                 if (err1) {
1123                         wl_entry_destroy(ubi, e);
1124                         err = err1;
1125                         goto out_ro;
1126                 }
1127                 return err;
1128         }
1129
1130         wl_entry_destroy(ubi, e);
1131         if (err != -EIO)
1132                 /*
1133                  * If this is not %-EIO, we have no idea what to do. Scheduling
1134                  * this physical eraseblock for erasure again would cause
1135                  * errors again and again. Well, lets switch to R/O mode.
1136                  */
1137                 goto out_ro;
1138
1139         /* It is %-EIO, the PEB went bad */
1140
1141         if (!ubi->bad_allowed) {
1142                 ubi_err(ubi, "bad physical eraseblock %d detected", pnum);
1143                 goto out_ro;
1144         }
1145
1146         spin_lock(&ubi->volumes_lock);
1147         if (ubi->beb_rsvd_pebs == 0) {
1148                 if (ubi->avail_pebs == 0) {
1149                         spin_unlock(&ubi->volumes_lock);
1150                         ubi_err(ubi, "no reserved/available physical eraseblocks");
1151                         goto out_ro;
1152                 }
1153                 ubi->avail_pebs -= 1;
1154                 available_consumed = 1;
1155         }
1156         spin_unlock(&ubi->volumes_lock);
1157
1158         ubi_msg(ubi, "mark PEB %d as bad", pnum);
1159         err = ubi_io_mark_bad(ubi, pnum);
1160         if (err)
1161                 goto out_ro;
1162
1163         spin_lock(&ubi->volumes_lock);
1164         if (ubi->beb_rsvd_pebs > 0) {
1165                 if (available_consumed) {
1166                         /*
1167                          * The amount of reserved PEBs increased since we last
1168                          * checked.
1169                          */
1170                         ubi->avail_pebs += 1;
1171                         available_consumed = 0;
1172                 }
1173                 ubi->beb_rsvd_pebs -= 1;
1174         }
1175         ubi->bad_peb_count += 1;
1176         ubi->good_peb_count -= 1;
1177         ubi_calculate_reserved(ubi);
1178         if (available_consumed)
1179                 ubi_warn(ubi, "no PEBs in the reserved pool, used an available PEB");
1180         else if (ubi->beb_rsvd_pebs)
1181                 ubi_msg(ubi, "%d PEBs left in the reserve",
1182                         ubi->beb_rsvd_pebs);
1183         else
1184                 ubi_warn(ubi, "last PEB from the reserve was used");
1185         spin_unlock(&ubi->volumes_lock);
1186
1187         return err;
1188
1189 out_ro:
1190         if (available_consumed) {
1191                 spin_lock(&ubi->volumes_lock);
1192                 ubi->avail_pebs += 1;
1193                 spin_unlock(&ubi->volumes_lock);
1194         }
1195         ubi_ro_mode(ubi);
1196         return err;
1197 }
1198
1199 static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
1200                           int shutdown)
1201 {
1202         int ret;
1203
1204         if (shutdown) {
1205                 struct ubi_wl_entry *e = wl_wrk->e;
1206
1207                 dbg_wl("cancel erasure of PEB %d EC %d", e->pnum, e->ec);
1208                 kfree(wl_wrk);
1209                 wl_entry_destroy(ubi, e);
1210                 return 0;
1211         }
1212
1213         ret = __erase_worker(ubi, wl_wrk);
1214         kfree(wl_wrk);
1215         return ret;
1216 }
1217
1218 /**
1219  * ubi_wl_put_peb - return a PEB to the wear-leveling sub-system.
1220  * @ubi: UBI device description object
1221  * @vol_id: the volume ID that last used this PEB
1222  * @lnum: the last used logical eraseblock number for the PEB
1223  * @pnum: physical eraseblock to return
1224  * @torture: if this physical eraseblock has to be tortured
1225  *
1226  * This function is called to return physical eraseblock @pnum to the pool of
1227  * free physical eraseblocks. The @torture flag has to be set if an I/O error
1228  * occurred to this @pnum and it has to be tested. This function returns zero
1229  * in case of success, and a negative error code in case of failure.
1230  */
1231 int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum,
1232                    int pnum, int torture)
1233 {
1234         int err;
1235         struct ubi_wl_entry *e;
1236
1237         dbg_wl("PEB %d", pnum);
1238         ubi_assert(pnum >= 0);
1239         ubi_assert(pnum < ubi->peb_count);
1240
1241         down_read(&ubi->fm_protect);
1242
1243 retry:
1244         spin_lock(&ubi->wl_lock);
1245         e = ubi->lookuptbl[pnum];
1246         if (e == ubi->move_from) {
1247                 /*
1248                  * User is putting the physical eraseblock which was selected to
1249                  * be moved. It will be scheduled for erasure in the
1250                  * wear-leveling worker.
1251                  */
1252                 dbg_wl("PEB %d is being moved, wait", pnum);
1253                 spin_unlock(&ubi->wl_lock);
1254
1255                 /* Wait for the WL worker by taking the @ubi->move_mutex */
1256                 mutex_lock(&ubi->move_mutex);
1257                 mutex_unlock(&ubi->move_mutex);
1258                 goto retry;
1259         } else if (e == ubi->move_to) {
1260                 /*
1261                  * User is putting the physical eraseblock which was selected
1262                  * as the target the data is moved to. It may happen if the EBA
1263                  * sub-system already re-mapped the LEB in 'ubi_eba_copy_leb()'
1264                  * but the WL sub-system has not put the PEB to the "used" tree
1265                  * yet, but it is about to do this. So we just set a flag which
1266                  * will tell the WL worker that the PEB is not needed anymore
1267                  * and should be scheduled for erasure.
1268                  */
1269                 dbg_wl("PEB %d is the target of data moving", pnum);
1270                 ubi_assert(!ubi->move_to_put);
1271                 ubi->move_to_put = 1;
1272                 spin_unlock(&ubi->wl_lock);
1273                 up_read(&ubi->fm_protect);
1274                 return 0;
1275         } else {
1276                 if (in_wl_tree(e, &ubi->used)) {
1277                         self_check_in_wl_tree(ubi, e, &ubi->used);
1278                         rb_erase(&e->u.rb, &ubi->used);
1279                 } else if (in_wl_tree(e, &ubi->scrub)) {
1280                         self_check_in_wl_tree(ubi, e, &ubi->scrub);
1281                         rb_erase(&e->u.rb, &ubi->scrub);
1282                 } else if (in_wl_tree(e, &ubi->erroneous)) {
1283                         self_check_in_wl_tree(ubi, e, &ubi->erroneous);
1284                         rb_erase(&e->u.rb, &ubi->erroneous);
1285                         ubi->erroneous_peb_count -= 1;
1286                         ubi_assert(ubi->erroneous_peb_count >= 0);
1287                         /* Erroneous PEBs should be tortured */
1288                         torture = 1;
1289                 } else {
1290                         err = prot_queue_del(ubi, e->pnum);
1291                         if (err) {
1292                                 ubi_err(ubi, "PEB %d not found", pnum);
1293                                 ubi_ro_mode(ubi);
1294                                 spin_unlock(&ubi->wl_lock);
1295                                 up_read(&ubi->fm_protect);
1296                                 return err;
1297                         }
1298                 }
1299         }
1300         spin_unlock(&ubi->wl_lock);
1301
1302         err = schedule_erase(ubi, e, vol_id, lnum, torture, false);
1303         if (err) {
1304                 spin_lock(&ubi->wl_lock);
1305                 wl_tree_add(e, &ubi->used);
1306                 spin_unlock(&ubi->wl_lock);
1307         }
1308
1309         up_read(&ubi->fm_protect);
1310         return err;
1311 }
1312
1313 /**
1314  * ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing.
1315  * @ubi: UBI device description object
1316  * @pnum: the physical eraseblock to schedule
1317  *
1318  * If a bit-flip in a physical eraseblock is detected, this physical eraseblock
1319  * needs scrubbing. This function schedules a physical eraseblock for
1320  * scrubbing which is done in background. This function returns zero in case of
1321  * success and a negative error code in case of failure.
1322  */
1323 int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum)
1324 {
1325         struct ubi_wl_entry *e;
1326
1327         ubi_msg(ubi, "schedule PEB %d for scrubbing", pnum);
1328
1329 retry:
1330         spin_lock(&ubi->wl_lock);
1331         e = ubi->lookuptbl[pnum];
1332         if (e == ubi->move_from || in_wl_tree(e, &ubi->scrub) ||
1333                                    in_wl_tree(e, &ubi->erroneous)) {
1334                 spin_unlock(&ubi->wl_lock);
1335                 return 0;
1336         }
1337
1338         if (e == ubi->move_to) {
1339                 /*
1340                  * This physical eraseblock was used to move data to. The data
1341                  * was moved but the PEB was not yet inserted to the proper
1342                  * tree. We should just wait a little and let the WL worker
1343                  * proceed.
1344                  */
1345                 spin_unlock(&ubi->wl_lock);
1346                 dbg_wl("the PEB %d is not in proper tree, retry", pnum);
1347                 yield();
1348                 goto retry;
1349         }
1350
1351         if (in_wl_tree(e, &ubi->used)) {
1352                 self_check_in_wl_tree(ubi, e, &ubi->used);
1353                 rb_erase(&e->u.rb, &ubi->used);
1354         } else {
1355                 int err;
1356
1357                 err = prot_queue_del(ubi, e->pnum);
1358                 if (err) {
1359                         ubi_err(ubi, "PEB %d not found", pnum);
1360                         ubi_ro_mode(ubi);
1361                         spin_unlock(&ubi->wl_lock);
1362                         return err;
1363                 }
1364         }
1365
1366         wl_tree_add(e, &ubi->scrub);
1367         spin_unlock(&ubi->wl_lock);
1368
1369         /*
1370          * Technically scrubbing is the same as wear-leveling, so it is done
1371          * by the WL worker.
1372          */
1373         return ensure_wear_leveling(ubi, 0);
1374 }
1375
1376 /**
1377  * ubi_wl_flush - flush all pending works.
1378  * @ubi: UBI device description object
1379  * @vol_id: the volume id to flush for
1380  * @lnum: the logical eraseblock number to flush for
1381  *
1382  * This function executes all pending works for a particular volume id /
1383  * logical eraseblock number pair. If either value is set to %UBI_ALL, then it
1384  * acts as a wildcard for all of the corresponding volume numbers or logical
1385  * eraseblock numbers. It returns zero in case of success and a negative error
1386  * code in case of failure.
1387  */
1388 int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum)
1389 {
1390         int err = 0;
1391         int found = 1;
1392
1393         /*
1394          * Erase while the pending works queue is not empty, but not more than
1395          * the number of currently pending works.
1396          */
1397         dbg_wl("flush pending work for LEB %d:%d (%d pending works)",
1398                vol_id, lnum, ubi->works_count);
1399
1400         while (found) {
1401                 struct ubi_work *wrk, *tmp;
1402                 found = 0;
1403
1404                 down_read(&ubi->work_sem);
1405                 spin_lock(&ubi->wl_lock);
1406                 list_for_each_entry_safe(wrk, tmp, &ubi->works, list) {
1407                         if ((vol_id == UBI_ALL || wrk->vol_id == vol_id) &&
1408                             (lnum == UBI_ALL || wrk->lnum == lnum)) {
1409                                 list_del(&wrk->list);
1410                                 ubi->works_count -= 1;
1411                                 ubi_assert(ubi->works_count >= 0);
1412                                 spin_unlock(&ubi->wl_lock);
1413
1414                                 err = wrk->func(ubi, wrk, 0);
1415                                 if (err) {
1416                                         up_read(&ubi->work_sem);
1417                                         return err;
1418                                 }
1419
1420                                 spin_lock(&ubi->wl_lock);
1421                                 found = 1;
1422                                 break;
1423                         }
1424                 }
1425                 spin_unlock(&ubi->wl_lock);
1426                 up_read(&ubi->work_sem);
1427         }
1428
1429         /*
1430          * Make sure all the works which have been done in parallel are
1431          * finished.
1432          */
1433         down_write(&ubi->work_sem);
1434         up_write(&ubi->work_sem);
1435
1436         return err;
1437 }
1438
1439 static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e)
1440 {
1441         if (in_wl_tree(e, &ubi->scrub))
1442                 return false;
1443         else if (in_wl_tree(e, &ubi->erroneous))
1444                 return false;
1445         else if (ubi->move_from == e)
1446                 return false;
1447         else if (ubi->move_to == e)
1448                 return false;
1449
1450         return true;
1451 }
1452
1453 /**
1454  * ubi_bitflip_check - Check an eraseblock for bitflips and scrub it if needed.
1455  * @ubi: UBI device description object
1456  * @pnum: the physical eraseblock to schedule
1457  * @force: dont't read the block, assume bitflips happened and take action.
1458  *
1459  * This function reads the given eraseblock and checks if bitflips occured.
1460  * In case of bitflips, the eraseblock is scheduled for scrubbing.
1461  * If scrubbing is forced with @force, the eraseblock is not read,
1462  * but scheduled for scrubbing right away.
1463  *
1464  * Returns:
1465  * %EINVAL, PEB is out of range
1466  * %ENOENT, PEB is no longer used by UBI
1467  * %EBUSY, PEB cannot be checked now or a check is currently running on it
1468  * %EAGAIN, bit flips happened but scrubbing is currently not possible
1469  * %EUCLEAN, bit flips happened and PEB is scheduled for scrubbing
1470  * %0, no bit flips detected
1471  */
1472 int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force)
1473 {
1474         int err = 0;
1475         struct ubi_wl_entry *e;
1476
1477         if (pnum < 0 || pnum >= ubi->peb_count) {
1478                 err = -EINVAL;
1479                 goto out;
1480         }
1481
1482         /*
1483          * Pause all parallel work, otherwise it can happen that the
1484          * erase worker frees a wl entry under us.
1485          */
1486         down_write(&ubi->work_sem);
1487
1488         /*
1489          * Make sure that the wl entry does not change state while
1490          * inspecting it.
1491          */
1492         spin_lock(&ubi->wl_lock);
1493         e = ubi->lookuptbl[pnum];
1494         if (!e) {
1495                 spin_unlock(&ubi->wl_lock);
1496                 err = -ENOENT;
1497                 goto out_resume;
1498         }
1499
1500         /*
1501          * Does it make sense to check this PEB?
1502          */
1503         if (!scrub_possible(ubi, e)) {
1504                 spin_unlock(&ubi->wl_lock);
1505                 err = -EBUSY;
1506                 goto out_resume;
1507         }
1508         spin_unlock(&ubi->wl_lock);
1509
1510         if (!force) {
1511                 mutex_lock(&ubi->buf_mutex);
1512                 err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
1513                 mutex_unlock(&ubi->buf_mutex);
1514         }
1515
1516         if (force || err == UBI_IO_BITFLIPS) {
1517                 /*
1518                  * Okay, bit flip happened, let's figure out what we can do.
1519                  */
1520                 spin_lock(&ubi->wl_lock);
1521
1522                 /*
1523                  * Recheck. We released wl_lock, UBI might have killed the
1524                  * wl entry under us.
1525                  */
1526                 e = ubi->lookuptbl[pnum];
1527                 if (!e) {
1528                         spin_unlock(&ubi->wl_lock);
1529                         err = -ENOENT;
1530                         goto out_resume;
1531                 }
1532
1533                 /*
1534                  * Need to re-check state
1535                  */
1536                 if (!scrub_possible(ubi, e)) {
1537                         spin_unlock(&ubi->wl_lock);
1538                         err = -EBUSY;
1539                         goto out_resume;
1540                 }
1541
1542                 if (in_pq(ubi, e)) {
1543                         prot_queue_del(ubi, e->pnum);
1544                         wl_tree_add(e, &ubi->scrub);
1545                         spin_unlock(&ubi->wl_lock);
1546
1547                         err = ensure_wear_leveling(ubi, 1);
1548                 } else if (in_wl_tree(e, &ubi->used)) {
1549                         rb_erase(&e->u.rb, &ubi->used);
1550                         wl_tree_add(e, &ubi->scrub);
1551                         spin_unlock(&ubi->wl_lock);
1552
1553                         err = ensure_wear_leveling(ubi, 1);
1554                 } else if (in_wl_tree(e, &ubi->free)) {
1555                         rb_erase(&e->u.rb, &ubi->free);
1556                         ubi->free_count--;
1557                         spin_unlock(&ubi->wl_lock);
1558
1559                         /*
1560                          * This PEB is empty we can schedule it for
1561                          * erasure right away. No wear leveling needed.
1562                          */
1563                         err = schedule_erase(ubi, e, UBI_UNKNOWN, UBI_UNKNOWN,
1564                                              force ? 0 : 1, true);
1565                 } else {
1566                         spin_unlock(&ubi->wl_lock);
1567                         err = -EAGAIN;
1568                 }
1569
1570                 if (!err && !force)
1571                         err = -EUCLEAN;
1572         } else {
1573                 err = 0;
1574         }
1575
1576 out_resume:
1577         up_write(&ubi->work_sem);
1578 out:
1579
1580         return err;
1581 }
1582
1583 /**
1584  * tree_destroy - destroy an RB-tree.
1585  * @ubi: UBI device description object
1586  * @root: the root of the tree to destroy
1587  */
1588 static void tree_destroy(struct ubi_device *ubi, struct rb_root *root)
1589 {
1590         struct rb_node *rb;
1591         struct ubi_wl_entry *e;
1592
1593         rb = root->rb_node;
1594         while (rb) {
1595                 if (rb->rb_left)
1596                         rb = rb->rb_left;
1597                 else if (rb->rb_right)
1598                         rb = rb->rb_right;
1599                 else {
1600                         e = rb_entry(rb, struct ubi_wl_entry, u.rb);
1601
1602                         rb = rb_parent(rb);
1603                         if (rb) {
1604                                 if (rb->rb_left == &e->u.rb)
1605                                         rb->rb_left = NULL;
1606                                 else
1607                                         rb->rb_right = NULL;
1608                         }
1609
1610                         wl_entry_destroy(ubi, e);
1611                 }
1612         }
1613 }
1614
1615 /**
1616  * ubi_thread - UBI background thread.
1617  * @u: the UBI device description object pointer
1618  */
1619 int ubi_thread(void *u)
1620 {
1621         int failures = 0;
1622         struct ubi_device *ubi = u;
1623
1624         ubi_msg(ubi, "background thread \"%s\" started, PID %d",
1625                 ubi->bgt_name, task_pid_nr(current));
1626
1627         set_freezable();
1628         for (;;) {
1629                 int err;
1630
1631                 if (kthread_should_stop())
1632                         break;
1633
1634                 if (try_to_freeze())
1635                         continue;
1636
1637                 spin_lock(&ubi->wl_lock);
1638                 if (list_empty(&ubi->works) || ubi->ro_mode ||
1639                     !ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
1640                         set_current_state(TASK_INTERRUPTIBLE);
1641                         spin_unlock(&ubi->wl_lock);
1642
1643                         /*
1644                          * Check kthread_should_stop() after we set the task
1645                          * state to guarantee that we either see the stop bit
1646                          * and exit or the task state is reset to runnable such
1647                          * that it's not scheduled out indefinitely and detects
1648                          * the stop bit at kthread_should_stop().
1649                          */
1650                         if (kthread_should_stop()) {
1651                                 set_current_state(TASK_RUNNING);
1652                                 break;
1653                         }
1654
1655                         schedule();
1656                         continue;
1657                 }
1658                 spin_unlock(&ubi->wl_lock);
1659
1660                 err = do_work(ubi);
1661                 if (err) {
1662                         ubi_err(ubi, "%s: work failed with error code %d",
1663                                 ubi->bgt_name, err);
1664                         if (failures++ > WL_MAX_FAILURES) {
1665                                 /*
1666                                  * Too many failures, disable the thread and
1667                                  * switch to read-only mode.
1668                                  */
1669                                 ubi_msg(ubi, "%s: %d consecutive failures",
1670                                         ubi->bgt_name, WL_MAX_FAILURES);
1671                                 ubi_ro_mode(ubi);
1672                                 ubi->thread_enabled = 0;
1673                                 continue;
1674                         }
1675                 } else
1676                         failures = 0;
1677
1678                 cond_resched();
1679         }
1680
1681         dbg_wl("background thread \"%s\" is killed", ubi->bgt_name);
1682         ubi->thread_enabled = 0;
1683         return 0;
1684 }
1685
1686 /**
1687  * shutdown_work - shutdown all pending works.
1688  * @ubi: UBI device description object
1689  */
1690 static void shutdown_work(struct ubi_device *ubi)
1691 {
1692         while (!list_empty(&ubi->works)) {
1693                 struct ubi_work *wrk;
1694
1695                 wrk = list_entry(ubi->works.next, struct ubi_work, list);
1696                 list_del(&wrk->list);
1697                 wrk->func(ubi, wrk, 1);
1698                 ubi->works_count -= 1;
1699                 ubi_assert(ubi->works_count >= 0);
1700         }
1701 }
1702
1703 /**
1704  * erase_aeb - erase a PEB given in UBI attach info PEB
1705  * @ubi: UBI device description object
1706  * @aeb: UBI attach info PEB
1707  * @sync: If true, erase synchronously. Otherwise schedule for erasure
1708  */
1709 static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync)
1710 {
1711         struct ubi_wl_entry *e;
1712         int err;
1713
1714         e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1715         if (!e)
1716                 return -ENOMEM;
1717
1718         e->pnum = aeb->pnum;
1719         e->ec = aeb->ec;
1720         ubi->lookuptbl[e->pnum] = e;
1721
1722         if (sync) {
1723                 err = sync_erase(ubi, e, false);
1724                 if (err)
1725                         goto out_free;
1726
1727                 wl_tree_add(e, &ubi->free);
1728                 ubi->free_count++;
1729         } else {
1730                 err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false);
1731                 if (err)
1732                         goto out_free;
1733         }
1734
1735         return 0;
1736
1737 out_free:
1738         wl_entry_destroy(ubi, e);
1739
1740         return err;
1741 }
1742
1743 /**
1744  * ubi_wl_init - initialize the WL sub-system using attaching information.
1745  * @ubi: UBI device description object
1746  * @ai: attaching information
1747  *
1748  * This function returns zero in case of success, and a negative error code in
1749  * case of failure.
1750  */
1751 int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
1752 {
1753         int err, i, reserved_pebs, found_pebs = 0;
1754         struct rb_node *rb1, *rb2;
1755         struct ubi_ainf_volume *av;
1756         struct ubi_ainf_peb *aeb, *tmp;
1757         struct ubi_wl_entry *e;
1758
1759         ubi->used = ubi->erroneous = ubi->free = ubi->scrub = RB_ROOT;
1760         spin_lock_init(&ubi->wl_lock);
1761         mutex_init(&ubi->move_mutex);
1762         init_rwsem(&ubi->work_sem);
1763         ubi->max_ec = ai->max_ec;
1764         INIT_LIST_HEAD(&ubi->works);
1765
1766         sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num);
1767
1768         err = -ENOMEM;
1769         ubi->lookuptbl = kcalloc(ubi->peb_count, sizeof(void *), GFP_KERNEL);
1770         if (!ubi->lookuptbl)
1771                 return err;
1772
1773         for (i = 0; i < UBI_PROT_QUEUE_LEN; i++)
1774                 INIT_LIST_HEAD(&ubi->pq[i]);
1775         ubi->pq_head = 0;
1776
1777         ubi->free_count = 0;
1778         list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
1779                 cond_resched();
1780
1781                 err = erase_aeb(ubi, aeb, false);
1782                 if (err)
1783                         goto out_free;
1784
1785                 found_pebs++;
1786         }
1787
1788         list_for_each_entry(aeb, &ai->free, u.list) {
1789                 cond_resched();
1790
1791                 e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1792                 if (!e) {
1793                         err = -ENOMEM;
1794                         goto out_free;
1795                 }
1796
1797                 e->pnum = aeb->pnum;
1798                 e->ec = aeb->ec;
1799                 ubi_assert(e->ec >= 0);
1800
1801                 wl_tree_add(e, &ubi->free);
1802                 ubi->free_count++;
1803
1804                 ubi->lookuptbl[e->pnum] = e;
1805
1806                 found_pebs++;
1807         }
1808
1809         ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1810                 ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1811                         cond_resched();
1812
1813                         e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1814                         if (!e) {
1815                                 err = -ENOMEM;
1816                                 goto out_free;
1817                         }
1818
1819                         e->pnum = aeb->pnum;
1820                         e->ec = aeb->ec;
1821                         ubi->lookuptbl[e->pnum] = e;
1822
1823                         if (!aeb->scrub) {
1824                                 dbg_wl("add PEB %d EC %d to the used tree",
1825                                        e->pnum, e->ec);
1826                                 wl_tree_add(e, &ubi->used);
1827                         } else {
1828                                 dbg_wl("add PEB %d EC %d to the scrub tree",
1829                                        e->pnum, e->ec);
1830                                 wl_tree_add(e, &ubi->scrub);
1831                         }
1832
1833                         found_pebs++;
1834                 }
1835         }
1836
1837         list_for_each_entry(aeb, &ai->fastmap, u.list) {
1838                 cond_resched();
1839
1840                 e = ubi_find_fm_block(ubi, aeb->pnum);
1841
1842                 if (e) {
1843                         ubi_assert(!ubi->lookuptbl[e->pnum]);
1844                         ubi->lookuptbl[e->pnum] = e;
1845                 } else {
1846                         bool sync = false;
1847
1848                         /*
1849                          * Usually old Fastmap PEBs are scheduled for erasure
1850                          * and we don't have to care about them but if we face
1851                          * an power cut before scheduling them we need to
1852                          * take care of them here.
1853                          */
1854                         if (ubi->lookuptbl[aeb->pnum])
1855                                 continue;
1856
1857                         /*
1858                          * The fastmap update code might not find a free PEB for
1859                          * writing the fastmap anchor to and then reuses the
1860                          * current fastmap anchor PEB. When this PEB gets erased
1861                          * and a power cut happens before it is written again we
1862                          * must make sure that the fastmap attach code doesn't
1863                          * find any outdated fastmap anchors, hence we erase the
1864                          * outdated fastmap anchor PEBs synchronously here.
1865                          */
1866                         if (aeb->vol_id == UBI_FM_SB_VOLUME_ID)
1867                                 sync = true;
1868
1869                         err = erase_aeb(ubi, aeb, sync);
1870                         if (err)
1871                                 goto out_free;
1872                 }
1873
1874                 found_pebs++;
1875         }
1876
1877         dbg_wl("found %i PEBs", found_pebs);
1878
1879         ubi_assert(ubi->good_peb_count == found_pebs);
1880
1881         reserved_pebs = WL_RESERVED_PEBS;
1882         ubi_fastmap_init(ubi, &reserved_pebs);
1883
1884         if (ubi->avail_pebs < reserved_pebs) {
1885                 ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
1886                         ubi->avail_pebs, reserved_pebs);
1887                 if (ubi->corr_peb_count)
1888                         ubi_err(ubi, "%d PEBs are corrupted and not used",
1889                                 ubi->corr_peb_count);
1890                 err = -ENOSPC;
1891                 goto out_free;
1892         }
1893         ubi->avail_pebs -= reserved_pebs;
1894         ubi->rsvd_pebs += reserved_pebs;
1895
1896         /* Schedule wear-leveling if needed */
1897         err = ensure_wear_leveling(ubi, 0);
1898         if (err)
1899                 goto out_free;
1900
1901 #ifdef CONFIG_MTD_UBI_FASTMAP
1902         if (!ubi->ro_mode && !ubi->fm_disabled)
1903                 ubi_ensure_anchor_pebs(ubi);
1904 #endif
1905         return 0;
1906
1907 out_free:
1908         shutdown_work(ubi);
1909         tree_destroy(ubi, &ubi->used);
1910         tree_destroy(ubi, &ubi->free);
1911         tree_destroy(ubi, &ubi->scrub);
1912         kfree(ubi->lookuptbl);
1913         return err;
1914 }
1915
1916 /**
1917  * protection_queue_destroy - destroy the protection queue.
1918  * @ubi: UBI device description object
1919  */
1920 static void protection_queue_destroy(struct ubi_device *ubi)
1921 {
1922         int i;
1923         struct ubi_wl_entry *e, *tmp;
1924
1925         for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {
1926                 list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {
1927                         list_del(&e->u.list);
1928                         wl_entry_destroy(ubi, e);
1929                 }
1930         }
1931 }
1932
1933 /**
1934  * ubi_wl_close - close the wear-leveling sub-system.
1935  * @ubi: UBI device description object
1936  */
1937 void ubi_wl_close(struct ubi_device *ubi)
1938 {
1939         dbg_wl("close the WL sub-system");
1940         ubi_fastmap_close(ubi);
1941         shutdown_work(ubi);
1942         protection_queue_destroy(ubi);
1943         tree_destroy(ubi, &ubi->used);
1944         tree_destroy(ubi, &ubi->erroneous);
1945         tree_destroy(ubi, &ubi->free);
1946         tree_destroy(ubi, &ubi->scrub);
1947         kfree(ubi->lookuptbl);
1948 }
1949
1950 /**
1951  * self_check_ec - make sure that the erase counter of a PEB is correct.
1952  * @ubi: UBI device description object
1953  * @pnum: the physical eraseblock number to check
1954  * @ec: the erase counter to check
1955  *
1956  * This function returns zero if the erase counter of physical eraseblock @pnum
1957  * is equivalent to @ec, and a negative error code if not or if an error
1958  * occurred.
1959  */
1960 static int self_check_ec(struct ubi_device *ubi, int pnum, int ec)
1961 {
1962         int err;
1963         long long read_ec;
1964         struct ubi_ec_hdr *ec_hdr;
1965
1966         if (!ubi_dbg_chk_gen(ubi))
1967                 return 0;
1968
1969         ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
1970         if (!ec_hdr)
1971                 return -ENOMEM;
1972
1973         err = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
1974         if (err && err != UBI_IO_BITFLIPS) {
1975                 /* The header does not have to exist */
1976                 err = 0;
1977                 goto out_free;
1978         }
1979
1980         read_ec = be64_to_cpu(ec_hdr->ec);
1981         if (ec != read_ec && read_ec - ec > 1) {
1982                 ubi_err(ubi, "self-check failed for PEB %d", pnum);
1983                 ubi_err(ubi, "read EC is %lld, should be %d", read_ec, ec);
1984                 dump_stack();
1985                 err = 1;
1986         } else
1987                 err = 0;
1988
1989 out_free:
1990         kfree(ec_hdr);
1991         return err;
1992 }
1993
1994 /**
1995  * self_check_in_wl_tree - check that wear-leveling entry is in WL RB-tree.
1996  * @ubi: UBI device description object
1997  * @e: the wear-leveling entry to check
1998  * @root: the root of the tree
1999  *
2000  * This function returns zero if @e is in the @root RB-tree and %-EINVAL if it
2001  * is not.
2002  */
2003 static int self_check_in_wl_tree(const struct ubi_device *ubi,
2004                                  struct ubi_wl_entry *e, struct rb_root *root)
2005 {
2006         if (!ubi_dbg_chk_gen(ubi))
2007                 return 0;
2008
2009         if (in_wl_tree(e, root))
2010                 return 0;
2011
2012         ubi_err(ubi, "self-check failed for PEB %d, EC %d, RB-tree %p ",
2013                 e->pnum, e->ec, root);
2014         dump_stack();
2015         return -EINVAL;
2016 }
2017
2018 /**
2019  * self_check_in_pq - check if wear-leveling entry is in the protection
2020  *                        queue.
2021  * @ubi: UBI device description object
2022  * @e: the wear-leveling entry to check
2023  *
2024  * This function returns zero if @e is in @ubi->pq and %-EINVAL if it is not.
2025  */
2026 static int self_check_in_pq(const struct ubi_device *ubi,
2027                             struct ubi_wl_entry *e)
2028 {
2029         if (!ubi_dbg_chk_gen(ubi))
2030                 return 0;
2031
2032         if (in_pq(ubi, e))
2033                 return 0;
2034
2035         ubi_err(ubi, "self-check failed for PEB %d, EC %d, Protect queue",
2036                 e->pnum, e->ec);
2037         dump_stack();
2038         return -EINVAL;
2039 }
2040 #ifndef CONFIG_MTD_UBI_FASTMAP
2041 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
2042 {
2043         struct ubi_wl_entry *e;
2044
2045         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
2046         self_check_in_wl_tree(ubi, e, &ubi->free);
2047         ubi->free_count--;
2048         ubi_assert(ubi->free_count >= 0);
2049         rb_erase(&e->u.rb, &ubi->free);
2050
2051         return e;
2052 }
2053
2054 /**
2055  * produce_free_peb - produce a free physical eraseblock.
2056  * @ubi: UBI device description object
2057  *
2058  * This function tries to make a free PEB by means of synchronous execution of
2059  * pending works. This may be needed if, for example the background thread is
2060  * disabled. Returns zero in case of success and a negative error code in case
2061  * of failure.
2062  */
2063 static int produce_free_peb(struct ubi_device *ubi)
2064 {
2065         int err;
2066
2067         while (!ubi->free.rb_node && ubi->works_count) {
2068                 spin_unlock(&ubi->wl_lock);
2069
2070                 dbg_wl("do one work synchronously");
2071                 err = do_work(ubi);
2072
2073                 spin_lock(&ubi->wl_lock);
2074                 if (err)
2075                         return err;
2076         }
2077
2078         return 0;
2079 }
2080
2081 /**
2082  * ubi_wl_get_peb - get a physical eraseblock.
2083  * @ubi: UBI device description object
2084  *
2085  * This function returns a physical eraseblock in case of success and a
2086  * negative error code in case of failure.
2087  * Returns with ubi->fm_eba_sem held in read mode!
2088  */
2089 int ubi_wl_get_peb(struct ubi_device *ubi)
2090 {
2091         int err;
2092         struct ubi_wl_entry *e;
2093
2094 retry:
2095         down_read(&ubi->fm_eba_sem);
2096         spin_lock(&ubi->wl_lock);
2097         if (!ubi->free.rb_node) {
2098                 if (ubi->works_count == 0) {
2099                         ubi_err(ubi, "no free eraseblocks");
2100                         ubi_assert(list_empty(&ubi->works));
2101                         spin_unlock(&ubi->wl_lock);
2102                         return -ENOSPC;
2103                 }
2104
2105                 err = produce_free_peb(ubi);
2106                 if (err < 0) {
2107                         spin_unlock(&ubi->wl_lock);
2108                         return err;
2109                 }
2110                 spin_unlock(&ubi->wl_lock);
2111                 up_read(&ubi->fm_eba_sem);
2112                 goto retry;
2113
2114         }
2115         e = wl_get_wle(ubi);
2116         prot_queue_add(ubi, e);
2117         spin_unlock(&ubi->wl_lock);
2118
2119         err = ubi_self_check_all_ff(ubi, e->pnum, ubi->vid_hdr_aloffset,
2120                                     ubi->peb_size - ubi->vid_hdr_aloffset);
2121         if (err) {
2122                 ubi_err(ubi, "new PEB %d does not contain all 0xFF bytes", e->pnum);
2123                 return err;
2124         }
2125
2126         return e->pnum;
2127 }
2128 #else
2129 #include "fastmap-wl.c"
2130 #endif