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 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 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 #ifdef CONFIG_MTD_UBI_FASTMAP
 674         if (!next_peb_for_wl(ubi) ||
 675 #else
 676         if (!ubi->free.rb_node ||
 677 #endif
 678             (!ubi->used.rb_node && !ubi->scrub.rb_node)) {
 679                 /*
 680                  * No free physical eraseblocks? Well, they must be waiting in
 681                  * the queue to be erased. Cancel movement - it will be
 682                  * triggered again when a free physical eraseblock appears.
 683                  *
 684                  * No used physical eraseblocks? They must be temporarily
 685                  * protected from being moved. They will be moved to the
 686                  * @ubi->used tree later and the wear-leveling will be
 687                  * triggered again.
 688                  */
 689                 dbg_wl("cancel WL, a list is empty: free %d, used %d",
 690                        !ubi->free.rb_node, !ubi->used.rb_node);
 691                 goto out_cancel;
 692         }
 693
 694 #ifdef CONFIG_MTD_UBI_FASTMAP
 695         e1 = find_anchor_wl_entry(&ubi->used);
 696         if (e1 && ubi->fm_anchor &&
 697             (ubi->fm_anchor->ec - e1->ec >= UBI_WL_THRESHOLD)) {
 698                 ubi->fm_do_produce_anchor = 1;
 699                 /*
 700                  * fm_anchor is no longer considered a good anchor.
 701                  * NULL assignment also prevents multiple wear level checks
 702                  * of this PEB.
 703                  */
 704                 wl_tree_add(ubi->fm_anchor, &ubi->free);
 705                 ubi->fm_anchor = NULL;
 706                 ubi->free_count++;
 707         }
 708
 709         if (ubi->fm_do_produce_anchor) {
 710                 if (!e1)
 711                         goto out_cancel;
 712                 e2 = get_peb_for_wl(ubi);
 713                 if (!e2)
 714                         goto out_cancel;
 715
 716                 self_check_in_wl_tree(ubi, e1, &ubi->used);
 717                 rb_erase(&e1->u.rb, &ubi->used);
 718                 dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
 719                 ubi->fm_do_produce_anchor = 0;
 720         } else if (!ubi->scrub.rb_node) {
 721 #else
 722         if (!ubi->scrub.rb_node) {
 723 #endif
 724                 /*
 725                  * Now pick the least worn-out used physical eraseblock and a
 726                  * highly worn-out free physical eraseblock. If the erase
 727                  * counters differ much enough, start wear-leveling.
 728                  */
 729                 e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
 730                 e2 = get_peb_for_wl(ubi);
 731                 if (!e2)
 732                         goto out_cancel;
 733
 734                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) {
 735                         dbg_wl("no WL needed: min used EC %d, max free EC %d",
 736                                e1->ec, e2->ec);
 737
 738                         /* Give the unused PEB back */
 739                         wl_tree_add(e2, &ubi->free);
 740                         ubi->free_count++;
 741                         goto out_cancel;
 742                 }
 743                 self_check_in_wl_tree(ubi, e1, &ubi->used);
 744                 rb_erase(&e1->u.rb, &ubi->used);
 745                 dbg_wl("move PEB %d EC %d to PEB %d EC %d",
 746                        e1->pnum, e1->ec, e2->pnum, e2->ec);
 747         } else {
 748                 /* Perform scrubbing */
 749                 scrubbing = 1;
 750                 e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
 751                 e2 = get_peb_for_wl(ubi);
 752                 if (!e2)
 753                         goto out_cancel;
 754
 755                 self_check_in_wl_tree(ubi, e1, &ubi->scrub);
 756                 rb_erase(&e1->u.rb, &ubi->scrub);
 757                 dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
 758         }
 759
 760         ubi->move_from = e1;
 761         ubi->move_to = e2;
 762         spin_unlock(&ubi->wl_lock);
 763
 764         /*
 765          * Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum.
 766          * We so far do not know which logical eraseblock our physical
 767          * eraseblock (@e1) belongs to. We have to read the volume identifier
 768          * header first.
 769          *
 770          * Note, we are protected from this PEB being unmapped and erased. The
 771          * 'ubi_wl_put_peb()' would wait for moving to be finished if the PEB
 772          * which is being moved was unmapped.
 773          */
 774
 775         err = ubi_io_read_vid_hdr(ubi, e1->pnum, vidb, 0);
 776         if (err && err != UBI_IO_BITFLIPS) {
 777                 dst_leb_clean = 1;
 778                 if (err == UBI_IO_FF) {
 779                         /*
 780                          * We are trying to move PEB without a VID header. UBI
 781                          * always write VID headers shortly after the PEB was
 782                          * given, so we have a situation when it has not yet
 783                          * had a chance to write it, because it was preempted.
 784                          * So add this PEB to the protection queue so far,
 785                          * because presumably more data will be written there
 786                          * (including the missing VID header), and then we'll
 787                          * move it.
 788                          */
 789                         dbg_wl("PEB %d has no VID header", e1->pnum);
 790                         protect = 1;
 791                         goto out_not_moved;
 792                 } else if (err == UBI_IO_FF_BITFLIPS) {
 793                         /*
 794                          * The same situation as %UBI_IO_FF, but bit-flips were
 795                          * detected. It is better to schedule this PEB for
 796                          * scrubbing.
 797                          */
 798                         dbg_wl("PEB %d has no VID header but has bit-flips",
 799                                e1->pnum);
 800                         scrubbing = 1;
 801                         goto out_not_moved;
 802                 } else if (ubi->fast_attach && err == UBI_IO_BAD_HDR_EBADMSG) {
 803                         /*
 804                          * While a full scan would detect interrupted erasures
 805                          * at attach time we can face them here when attached from
 806                          * Fastmap.
 807                          */
 808                         dbg_wl("PEB %d has ECC errors, maybe from an interrupted erasure",
 809                                e1->pnum);
 810                         erase = 1;
 811                         goto out_not_moved;
 812                 }
 813
 814                 ubi_err(ubi, "error %d while reading VID header from PEB %d",
 815                         err, e1->pnum);
 816                 goto out_error;
 817         }
 818
 819         vol_id = be32_to_cpu(vid_hdr->vol_id);
 820         lnum = be32_to_cpu(vid_hdr->lnum);
 821
 822         err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vidb);
 823         if (err) {
 824                 if (err == MOVE_CANCEL_RACE) {
 825                         /*
 826                          * The LEB has not been moved because the volume is
 827                          * being deleted or the PEB has been put meanwhile. We
 828                          * should prevent this PEB from being selected for
 829                          * wear-leveling movement again, so put it to the
 830                          * protection queue.
 831                          */
 832                         protect = 1;
 833                         dst_leb_clean = 1;
 834                         goto out_not_moved;
 835                 }
 836                 if (err == MOVE_RETRY) {
 837                         scrubbing = 1;
 838                         dst_leb_clean = 1;
 839                         goto out_not_moved;
 840                 }
 841                 if (err == MOVE_TARGET_BITFLIPS || err == MOVE_TARGET_WR_ERR ||
 842                     err == MOVE_TARGET_RD_ERR) {
 843                         /*
 844                          * Target PEB had bit-flips or write error - torture it.
 845                          */
 846                         torture = 1;
 847                         keep = 1;
 848                         goto out_not_moved;
 849                 }
 850
 851                 if (err == MOVE_SOURCE_RD_ERR) {
 852                         /*
 853                          * An error happened while reading the source PEB. Do
 854                          * not switch to R/O mode in this case, and give the
 855                          * upper layers a possibility to recover from this,
 856                          * e.g. by unmapping corresponding LEB. Instead, just
 857                          * put this PEB to the @ubi->erroneous list to prevent
 858                          * UBI from trying to move it over and over again.
 859                          */
 860                         if (ubi->erroneous_peb_count > ubi->max_erroneous) {
 861                                 ubi_err(ubi, "too many erroneous eraseblocks (%d)",
 862                                         ubi->erroneous_peb_count);
 863                                 goto out_error;
 864                         }
 865                         dst_leb_clean = 1;
 866                         erroneous = 1;
 867                         goto out_not_moved;
 868                 }
 869
 870                 if (err < 0)
 871                         goto out_error;
 872
 873                 ubi_assert(0);
 874         }
 875
 876         /* The PEB has been successfully moved */
 877         if (scrubbing)
 878                 ubi_msg(ubi, "scrubbed PEB %d (LEB %d:%d), data moved to PEB %d",
 879                         e1->pnum, vol_id, lnum, e2->pnum);
 880         ubi_free_vid_buf(vidb);
 881
 882         spin_lock(&ubi->wl_lock);
 883         if (!ubi->move_to_put) {
 884                 wl_tree_add(e2, &ubi->used);
 885                 e2 = NULL;
 886         }
 887         ubi->move_from = ubi->move_to = NULL;
 888         ubi->move_to_put = ubi->wl_scheduled = 0;
 889         spin_unlock(&ubi->wl_lock);
 890
 891         err = do_sync_erase(ubi, e1, vol_id, lnum, 0);
 892         if (err) {
 893                 if (e2)
 894                         wl_entry_destroy(ubi, e2);
 895                 goto out_ro;
 896         }
 897
 898         if (e2) {
 899                 /*
 900                  * Well, the target PEB was put meanwhile, schedule it for
 901                  * erasure.
 902                  */
 903                 dbg_wl("PEB %d (LEB %d:%d) was put meanwhile, erase",
 904                        e2->pnum, vol_id, lnum);
 905                 err = do_sync_erase(ubi, e2, vol_id, lnum, 0);
 906                 if (err)
 907                         goto out_ro;
 908         }
 909
 910         dbg_wl("done");
 911         mutex_unlock(&ubi->move_mutex);
 912         up_read(&ubi->fm_eba_sem);
 913         return 0;
 914
 915         /*
 916          * For some reasons the LEB was not moved, might be an error, might be
 917          * something else. @e1 was not changed, so return it back. @e2 might
 918          * have been changed, schedule it for erasure.
 919          */
 920 out_not_moved:
 921         if (vol_id != -1)
 922                 dbg_wl("cancel moving PEB %d (LEB %d:%d) to PEB %d (%d)",
 923                        e1->pnum, vol_id, lnum, e2->pnum, err);
 924         else
 925                 dbg_wl("cancel moving PEB %d to PEB %d (%d)",
 926                        e1->pnum, e2->pnum, err);
 927         spin_lock(&ubi->wl_lock);
 928         if (protect)
 929                 prot_queue_add(ubi, e1);
 930         else if (erroneous) {
 931                 wl_tree_add(e1, &ubi->erroneous);
 932                 ubi->erroneous_peb_count += 1;
 933         } else if (scrubbing)
 934                 wl_tree_add(e1, &ubi->scrub);
 935         else if (keep)
 936                 wl_tree_add(e1, &ubi->used);
 937         if (dst_leb_clean) {
 938                 wl_tree_add(e2, &ubi->free);
 939                 ubi->free_count++;
 940         }
 941
 942         ubi_assert(!ubi->move_to_put);
 943         ubi->move_from = ubi->move_to = NULL;
 944         ubi->wl_scheduled = 0;
 945         spin_unlock(&ubi->wl_lock);
 946
 947         ubi_free_vid_buf(vidb);
 948         if (dst_leb_clean) {
 949                 ensure_wear_leveling(ubi, 1);
 950         } else {
 951                 err = do_sync_erase(ubi, e2, vol_id, lnum, torture);
 952                 if (err)
 953                         goto out_ro;
 954         }
 955
 956         if (erase) {
 957                 err = do_sync_erase(ubi, e1, vol_id, lnum, 1);
 958                 if (err)
 959                         goto out_ro;
 960         }
 961
 962         mutex_unlock(&ubi->move_mutex);
 963         up_read(&ubi->fm_eba_sem);
 964         return 0;
 965
 966 out_error:
 967         if (vol_id != -1)
 968                 ubi_err(ubi, "error %d while moving PEB %d to PEB %d",
 969                         err, e1->pnum, e2->pnum);
 970         else
 971                 ubi_err(ubi, "error %d while moving PEB %d (LEB %d:%d) to PEB %d",
 972                         err, e1->pnum, vol_id, lnum, e2->pnum);
 973         spin_lock(&ubi->wl_lock);
 974         ubi->move_from = ubi->move_to = NULL;
 975         ubi->move_to_put = ubi->wl_scheduled = 0;
 976         spin_unlock(&ubi->wl_lock);
 977
 978         ubi_free_vid_buf(vidb);
 979         wl_entry_destroy(ubi, e1);
 980         wl_entry_destroy(ubi, e2);
 981
 982 out_ro:
 983         ubi_ro_mode(ubi);
 984         mutex_unlock(&ubi->move_mutex);
 985         up_read(&ubi->fm_eba_sem);
 986         ubi_assert(err != 0);
 987         return err < 0 ? err : -EIO;
 988
 989 out_cancel:
 990         ubi->wl_scheduled = 0;
 991         spin_unlock(&ubi->wl_lock);
 992         mutex_unlock(&ubi->move_mutex);
 993         up_read(&ubi->fm_eba_sem);
 994         ubi_free_vid_buf(vidb);
 995         return 0;
 996 }
 997
 998 /**
 999  * ensure_wear_leveling - schedule wear-leveling if it is needed.
1000  * @ubi: UBI device description object
1001  * @nested: set to non-zero if this function is called from UBI worker
1002  *
1003  * This function checks if it is time to start wear-leveling and schedules it
1004  * if yes. This function returns zero in case of success and a negative error
1005  * code in case of failure.
1006  */
1007 static int ensure_wear_leveling(struct ubi_device *ubi, int nested)
1008 {
1009         int err = 0;
1010         struct ubi_work *wrk;
1011
1012         spin_lock(&ubi->wl_lock);
1013         if (ubi->wl_scheduled)
1014                 /* Wear-leveling is already in the work queue */
1015                 goto out_unlock;
1016
1017         /*
1018          * If the ubi->scrub tree is not empty, scrubbing is needed, and the
1019          * WL worker has to be scheduled anyway.
1020          */
1021         if (!ubi->scrub.rb_node) {
1022 #ifdef CONFIG_MTD_UBI_FASTMAP
1023                 if (!need_wear_leveling(ubi))
1024                         goto out_unlock;
1025 #else
1026                 struct ubi_wl_entry *e1;
1027                 struct ubi_wl_entry *e2;
1028
1029                 if (!ubi->used.rb_node || !ubi->free.rb_node)
1030                         /* No physical eraseblocks - no deal */
1031                         goto out_unlock;
1032
1033                 /*
1034                  * We schedule wear-leveling only if the difference between the
1035                  * lowest erase counter of used physical eraseblocks and a high
1036                  * erase counter of free physical eraseblocks is greater than
1037                  * %UBI_WL_THRESHOLD.
1038                  */
1039                 e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
1040                 e2 = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
1041
1042                 if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD))
1043                         goto out_unlock;
1044 #endif
1045                 dbg_wl("schedule wear-leveling");
1046         } else
1047                 dbg_wl("schedule scrubbing");
1048
1049         ubi->wl_scheduled = 1;
1050         spin_unlock(&ubi->wl_lock);
1051
1052         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
1053         if (!wrk) {
1054                 err = -ENOMEM;
1055                 goto out_cancel;
1056         }
1057
1058         wrk->func = &wear_leveling_worker;
1059         if (nested)
1060                 __schedule_ubi_work(ubi, wrk);
1061         else
1062                 schedule_ubi_work(ubi, wrk);
1063         return err;
1064
1065 out_cancel:
1066         spin_lock(&ubi->wl_lock);
1067         ubi->wl_scheduled = 0;
1068 out_unlock:
1069         spin_unlock(&ubi->wl_lock);
1070         return err;
1071 }
1072
1073 /**
1074  * __erase_worker - physical eraseblock erase worker function.
1075  * @ubi: UBI device description object
1076  * @wl_wrk: the work object
1077  *
1078  * This function erases a physical eraseblock and perform torture testing if
1079  * needed. It also takes care about marking the physical eraseblock bad if
1080  * needed. Returns zero in case of success and a negative error code in case of
1081  * failure.
1082  */
1083 static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
1084 {
1085         struct ubi_wl_entry *e = wl_wrk->e;
1086         int pnum = e->pnum;
1087         int vol_id = wl_wrk->vol_id;
1088         int lnum = wl_wrk->lnum;
1089         int err, available_consumed = 0;
1090
1091         dbg_wl("erase PEB %d EC %d LEB %d:%d",
1092                pnum, e->ec, wl_wrk->vol_id, wl_wrk->lnum);
1093
1094         err = sync_erase(ubi, e, wl_wrk->torture);
1095         if (!err) {
1096                 spin_lock(&ubi->wl_lock);
1097
1098                 if (!ubi->fm_disabled && !ubi->fm_anchor &&
1099                     e->pnum < UBI_FM_MAX_START) {
1100                         /*
1101                          * Abort anchor production, if needed it will be
1102                          * enabled again in the wear leveling started below.
1103                          */
1104                         ubi->fm_anchor = e;
1105                         ubi->fm_do_produce_anchor = 0;
1106                 } else {
1107                         wl_tree_add(e, &ubi->free);
1108                         ubi->free_count++;
1109                 }
1110
1111                 spin_unlock(&ubi->wl_lock);
1112
1113                 /*
1114                  * One more erase operation has happened, take care about
1115                  * protected physical eraseblocks.
1116                  */
1117                 serve_prot_queue(ubi);
1118
1119                 /* And take care about wear-leveling */
1120                 err = ensure_wear_leveling(ubi, 1);
1121                 return err;
1122         }
1123
1124         ubi_err(ubi, "failed to erase PEB %d, error %d", pnum, err);
1125
1126         if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
1127             err == -EBUSY) {
1128                 int err1;
1129
1130                 /* Re-schedule the LEB for erasure */
1131                 err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false);
1132                 if (err1) {
1133                         wl_entry_destroy(ubi, e);
1134                         err = err1;
1135                         goto out_ro;
1136                 }
1137                 return err;
1138         }
1139
1140         wl_entry_destroy(ubi, e);
1141         if (err != -EIO)
1142                 /*
1143                  * If this is not %-EIO, we have no idea what to do. Scheduling
1144                  * this physical eraseblock for erasure again would cause
1145                  * errors again and again. Well, lets switch to R/O mode.
1146                  */
1147                 goto out_ro;
1148
1149         /* It is %-EIO, the PEB went bad */
1150
1151         if (!ubi->bad_allowed) {
1152                 ubi_err(ubi, "bad physical eraseblock %d detected", pnum);
1153                 goto out_ro;
1154         }
1155
1156         spin_lock(&ubi->volumes_lock);
1157         if (ubi->beb_rsvd_pebs == 0) {
1158                 if (ubi->avail_pebs == 0) {
1159                         spin_unlock(&ubi->volumes_lock);
1160                         ubi_err(ubi, "no reserved/available physical eraseblocks");
1161                         goto out_ro;
1162                 }
1163                 ubi->avail_pebs -= 1;
1164                 available_consumed = 1;
1165         }
1166         spin_unlock(&ubi->volumes_lock);
1167
1168         ubi_msg(ubi, "mark PEB %d as bad", pnum);
1169         err = ubi_io_mark_bad(ubi, pnum);
1170         if (err)
1171                 goto out_ro;
1172
1173         spin_lock(&ubi->volumes_lock);
1174         if (ubi->beb_rsvd_pebs > 0) {
1175                 if (available_consumed) {
1176                         /*
1177                          * The amount of reserved PEBs increased since we last
1178                          * checked.
1179                          */
1180                         ubi->avail_pebs += 1;
1181                         available_consumed = 0;
1182                 }
1183                 ubi->beb_rsvd_pebs -= 1;
1184         }
1185         ubi->bad_peb_count += 1;
1186         ubi->good_peb_count -= 1;
1187         ubi_calculate_reserved(ubi);
1188         if (available_consumed)
1189                 ubi_warn(ubi, "no PEBs in the reserved pool, used an available PEB");
1190         else if (ubi->beb_rsvd_pebs)
1191                 ubi_msg(ubi, "%d PEBs left in the reserve",
1192                         ubi->beb_rsvd_pebs);
1193         else
1194                 ubi_warn(ubi, "last PEB from the reserve was used");
1195         spin_unlock(&ubi->volumes_lock);
1196
1197         return err;
1198
1199 out_ro:
1200         if (available_consumed) {
1201                 spin_lock(&ubi->volumes_lock);
1202                 ubi->avail_pebs += 1;
1203                 spin_unlock(&ubi->volumes_lock);
1204         }
1205         ubi_ro_mode(ubi);
1206         return err;
1207 }
1208
1209 static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
1210                           int shutdown)
1211 {
1212         int ret;
1213
1214         if (shutdown) {
1215                 struct ubi_wl_entry *e = wl_wrk->e;
1216
1217                 dbg_wl("cancel erasure of PEB %d EC %d", e->pnum, e->ec);
1218                 kfree(wl_wrk);
1219                 wl_entry_destroy(ubi, e);
1220                 return 0;
1221         }
1222
1223         ret = __erase_worker(ubi, wl_wrk);
1224         kfree(wl_wrk);
1225         return ret;
1226 }
1227
1228 /**
1229  * ubi_wl_put_peb - return a PEB to the wear-leveling sub-system.
1230  * @ubi: UBI device description object
1231  * @vol_id: the volume ID that last used this PEB
1232  * @lnum: the last used logical eraseblock number for the PEB
1233  * @pnum: physical eraseblock to return
1234  * @torture: if this physical eraseblock has to be tortured
1235  *
1236  * This function is called to return physical eraseblock @pnum to the pool of
1237  * free physical eraseblocks. The @torture flag has to be set if an I/O error
1238  * occurred to this @pnum and it has to be tested. This function returns zero
1239  * in case of success, and a negative error code in case of failure.
1240  */
1241 int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum,
1242                    int pnum, int torture)
1243 {
1244         int err;
1245         struct ubi_wl_entry *e;
1246
1247         dbg_wl("PEB %d", pnum);
1248         ubi_assert(pnum >= 0);
1249         ubi_assert(pnum < ubi->peb_count);
1250
1251         down_read(&ubi->fm_protect);
1252
1253 retry:
1254         spin_lock(&ubi->wl_lock);
1255         e = ubi->lookuptbl[pnum];
1256         if (e == ubi->move_from) {
1257                 /*
1258                  * User is putting the physical eraseblock which was selected to
1259                  * be moved. It will be scheduled for erasure in the
1260                  * wear-leveling worker.
1261                  */
1262                 dbg_wl("PEB %d is being moved, wait", pnum);
1263                 spin_unlock(&ubi->wl_lock);
1264
1265                 /* Wait for the WL worker by taking the @ubi->move_mutex */
1266                 mutex_lock(&ubi->move_mutex);
1267                 mutex_unlock(&ubi->move_mutex);
1268                 goto retry;
1269         } else if (e == ubi->move_to) {
1270                 /*
1271                  * User is putting the physical eraseblock which was selected
1272                  * as the target the data is moved to. It may happen if the EBA
1273                  * sub-system already re-mapped the LEB in 'ubi_eba_copy_leb()'
1274                  * but the WL sub-system has not put the PEB to the "used" tree
1275                  * yet, but it is about to do this. So we just set a flag which
1276                  * will tell the WL worker that the PEB is not needed anymore
1277                  * and should be scheduled for erasure.
1278                  */
1279                 dbg_wl("PEB %d is the target of data moving", pnum);
1280                 ubi_assert(!ubi->move_to_put);
1281                 ubi->move_to_put = 1;
1282                 spin_unlock(&ubi->wl_lock);
1283                 up_read(&ubi->fm_protect);
1284                 return 0;
1285         } else {
1286                 if (in_wl_tree(e, &ubi->used)) {
1287                         self_check_in_wl_tree(ubi, e, &ubi->used);
1288                         rb_erase(&e->u.rb, &ubi->used);
1289                 } else if (in_wl_tree(e, &ubi->scrub)) {
1290                         self_check_in_wl_tree(ubi, e, &ubi->scrub);
1291                         rb_erase(&e->u.rb, &ubi->scrub);
1292                 } else if (in_wl_tree(e, &ubi->erroneous)) {
1293                         self_check_in_wl_tree(ubi, e, &ubi->erroneous);
1294                         rb_erase(&e->u.rb, &ubi->erroneous);
1295                         ubi->erroneous_peb_count -= 1;
1296                         ubi_assert(ubi->erroneous_peb_count >= 0);
1297                         /* Erroneous PEBs should be tortured */
1298                         torture = 1;
1299                 } else {
1300                         err = prot_queue_del(ubi, e->pnum);
1301                         if (err) {
1302                                 ubi_err(ubi, "PEB %d not found", pnum);
1303                                 ubi_ro_mode(ubi);
1304                                 spin_unlock(&ubi->wl_lock);
1305                                 up_read(&ubi->fm_protect);
1306                                 return err;
1307                         }
1308                 }
1309         }
1310         spin_unlock(&ubi->wl_lock);
1311
1312         err = schedule_erase(ubi, e, vol_id, lnum, torture, false);
1313         if (err) {
1314                 spin_lock(&ubi->wl_lock);
1315                 wl_tree_add(e, &ubi->used);
1316                 spin_unlock(&ubi->wl_lock);
1317         }
1318
1319         up_read(&ubi->fm_protect);
1320         return err;
1321 }
1322
1323 /**
1324  * ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing.
1325  * @ubi: UBI device description object
1326  * @pnum: the physical eraseblock to schedule
1327  *
1328  * If a bit-flip in a physical eraseblock is detected, this physical eraseblock
1329  * needs scrubbing. This function schedules a physical eraseblock for
1330  * scrubbing which is done in background. This function returns zero in case of
1331  * success and a negative error code in case of failure.
1332  */
1333 int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum)
1334 {
1335         struct ubi_wl_entry *e;
1336
1337         ubi_msg(ubi, "schedule PEB %d for scrubbing", pnum);
1338
1339 retry:
1340         spin_lock(&ubi->wl_lock);
1341         e = ubi->lookuptbl[pnum];
1342         if (e == ubi->move_from || in_wl_tree(e, &ubi->scrub) ||
1343                                    in_wl_tree(e, &ubi->erroneous)) {
1344                 spin_unlock(&ubi->wl_lock);
1345                 return 0;
1346         }
1347
1348         if (e == ubi->move_to) {
1349                 /*
1350                  * This physical eraseblock was used to move data to. The data
1351                  * was moved but the PEB was not yet inserted to the proper
1352                  * tree. We should just wait a little and let the WL worker
1353                  * proceed.
1354                  */
1355                 spin_unlock(&ubi->wl_lock);
1356                 dbg_wl("the PEB %d is not in proper tree, retry", pnum);
1357                 yield();
1358                 goto retry;
1359         }
1360
1361         if (in_wl_tree(e, &ubi->used)) {
1362                 self_check_in_wl_tree(ubi, e, &ubi->used);
1363                 rb_erase(&e->u.rb, &ubi->used);
1364         } else {
1365                 int err;
1366
1367                 err = prot_queue_del(ubi, e->pnum);
1368                 if (err) {
1369                         ubi_err(ubi, "PEB %d not found", pnum);
1370                         ubi_ro_mode(ubi);
1371                         spin_unlock(&ubi->wl_lock);
1372                         return err;
1373                 }
1374         }
1375
1376         wl_tree_add(e, &ubi->scrub);
1377         spin_unlock(&ubi->wl_lock);
1378
1379         /*
1380          * Technically scrubbing is the same as wear-leveling, so it is done
1381          * by the WL worker.
1382          */
1383         return ensure_wear_leveling(ubi, 0);
1384 }
1385
1386 /**
1387  * ubi_wl_flush - flush all pending works.
1388  * @ubi: UBI device description object
1389  * @vol_id: the volume id to flush for
1390  * @lnum: the logical eraseblock number to flush for
1391  *
1392  * This function executes all pending works for a particular volume id /
1393  * logical eraseblock number pair. If either value is set to %UBI_ALL, then it
1394  * acts as a wildcard for all of the corresponding volume numbers or logical
1395  * eraseblock numbers. It returns zero in case of success and a negative error
1396  * code in case of failure.
1397  */
1398 int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum)
1399 {
1400         int err = 0;
1401         int found = 1;
1402
1403         /*
1404          * Erase while the pending works queue is not empty, but not more than
1405          * the number of currently pending works.
1406          */
1407         dbg_wl("flush pending work for LEB %d:%d (%d pending works)",
1408                vol_id, lnum, ubi->works_count);
1409
1410         while (found) {
1411                 struct ubi_work *wrk, *tmp;
1412                 found = 0;
1413
1414                 down_read(&ubi->work_sem);
1415                 spin_lock(&ubi->wl_lock);
1416                 list_for_each_entry_safe(wrk, tmp, &ubi->works, list) {
1417                         if ((vol_id == UBI_ALL || wrk->vol_id == vol_id) &&
1418                             (lnum == UBI_ALL || wrk->lnum == lnum)) {
1419                                 list_del(&wrk->list);
1420                                 ubi->works_count -= 1;
1421                                 ubi_assert(ubi->works_count >= 0);
1422                                 spin_unlock(&ubi->wl_lock);
1423
1424                                 err = wrk->func(ubi, wrk, 0);
1425                                 if (err) {
1426                                         up_read(&ubi->work_sem);
1427                                         return err;
1428                                 }
1429
1430                                 spin_lock(&ubi->wl_lock);
1431                                 found = 1;
1432                                 break;
1433                         }
1434                 }
1435                 spin_unlock(&ubi->wl_lock);
1436                 up_read(&ubi->work_sem);
1437         }
1438
1439         /*
1440          * Make sure all the works which have been done in parallel are
1441          * finished.
1442          */
1443         down_write(&ubi->work_sem);
1444         up_write(&ubi->work_sem);
1445
1446         return err;
1447 }
1448
1449 static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e)
1450 {
1451         if (in_wl_tree(e, &ubi->scrub))
1452                 return false;
1453         else if (in_wl_tree(e, &ubi->erroneous))
1454                 return false;
1455         else if (ubi->move_from == e)
1456                 return false;
1457         else if (ubi->move_to == e)
1458                 return false;
1459
1460         return true;
1461 }
1462
1463 /**
1464  * ubi_bitflip_check - Check an eraseblock for bitflips and scrub it if needed.
1465  * @ubi: UBI device description object
1466  * @pnum: the physical eraseblock to schedule
1467  * @force: don't read the block, assume bitflips happened and take action.
1468  *
1469  * This function reads the given eraseblock and checks if bitflips occured.
1470  * In case of bitflips, the eraseblock is scheduled for scrubbing.
1471  * If scrubbing is forced with @force, the eraseblock is not read,
1472  * but scheduled for scrubbing right away.
1473  *
1474  * Returns:
1475  * %EINVAL, PEB is out of range
1476  * %ENOENT, PEB is no longer used by UBI
1477  * %EBUSY, PEB cannot be checked now or a check is currently running on it
1478  * %EAGAIN, bit flips happened but scrubbing is currently not possible
1479  * %EUCLEAN, bit flips happened and PEB is scheduled for scrubbing
1480  * %0, no bit flips detected
1481  */
1482 int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force)
1483 {
1484         int err = 0;
1485         struct ubi_wl_entry *e;
1486
1487         if (pnum < 0 || pnum >= ubi->peb_count) {
1488                 err = -EINVAL;
1489                 goto out;
1490         }
1491
1492         /*
1493          * Pause all parallel work, otherwise it can happen that the
1494          * erase worker frees a wl entry under us.
1495          */
1496         down_write(&ubi->work_sem);
1497
1498         /*
1499          * Make sure that the wl entry does not change state while
1500          * inspecting it.
1501          */
1502         spin_lock(&ubi->wl_lock);
1503         e = ubi->lookuptbl[pnum];
1504         if (!e) {
1505                 spin_unlock(&ubi->wl_lock);
1506                 err = -ENOENT;
1507                 goto out_resume;
1508         }
1509
1510         /*
1511          * Does it make sense to check this PEB?
1512          */
1513         if (!scrub_possible(ubi, e)) {
1514                 spin_unlock(&ubi->wl_lock);
1515                 err = -EBUSY;
1516                 goto out_resume;
1517         }
1518         spin_unlock(&ubi->wl_lock);
1519
1520         if (!force) {
1521                 mutex_lock(&ubi->buf_mutex);
1522                 err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
1523                 mutex_unlock(&ubi->buf_mutex);
1524         }
1525
1526         if (force || err == UBI_IO_BITFLIPS) {
1527                 /*
1528                  * Okay, bit flip happened, let's figure out what we can do.
1529                  */
1530                 spin_lock(&ubi->wl_lock);
1531
1532                 /*
1533                  * Recheck. We released wl_lock, UBI might have killed the
1534                  * wl entry under us.
1535                  */
1536                 e = ubi->lookuptbl[pnum];
1537                 if (!e) {
1538                         spin_unlock(&ubi->wl_lock);
1539                         err = -ENOENT;
1540                         goto out_resume;
1541                 }
1542
1543                 /*
1544                  * Need to re-check state
1545                  */
1546                 if (!scrub_possible(ubi, e)) {
1547                         spin_unlock(&ubi->wl_lock);
1548                         err = -EBUSY;
1549                         goto out_resume;
1550                 }
1551
1552                 if (in_pq(ubi, e)) {
1553                         prot_queue_del(ubi, e->pnum);
1554                         wl_tree_add(e, &ubi->scrub);
1555                         spin_unlock(&ubi->wl_lock);
1556
1557                         err = ensure_wear_leveling(ubi, 1);
1558                 } else if (in_wl_tree(e, &ubi->used)) {
1559                         rb_erase(&e->u.rb, &ubi->used);
1560                         wl_tree_add(e, &ubi->scrub);
1561                         spin_unlock(&ubi->wl_lock);
1562
1563                         err = ensure_wear_leveling(ubi, 1);
1564                 } else if (in_wl_tree(e, &ubi->free)) {
1565                         rb_erase(&e->u.rb, &ubi->free);
1566                         ubi->free_count--;
1567                         spin_unlock(&ubi->wl_lock);
1568
1569                         /*
1570                          * This PEB is empty we can schedule it for
1571                          * erasure right away. No wear leveling needed.
1572                          */
1573                         err = schedule_erase(ubi, e, UBI_UNKNOWN, UBI_UNKNOWN,
1574                                              force ? 0 : 1, true);
1575                 } else {
1576                         spin_unlock(&ubi->wl_lock);
1577                         err = -EAGAIN;
1578                 }
1579
1580                 if (!err && !force)
1581                         err = -EUCLEAN;
1582         } else {
1583                 err = 0;
1584         }
1585
1586 out_resume:
1587         up_write(&ubi->work_sem);
1588 out:
1589
1590         return err;
1591 }
1592
1593 /**
1594  * tree_destroy - destroy an RB-tree.
1595  * @ubi: UBI device description object
1596  * @root: the root of the tree to destroy
1597  */
1598 static void tree_destroy(struct ubi_device *ubi, struct rb_root *root)
1599 {
1600         struct rb_node *rb;
1601         struct ubi_wl_entry *e;
1602
1603         rb = root->rb_node;
1604         while (rb) {
1605                 if (rb->rb_left)
1606                         rb = rb->rb_left;
1607                 else if (rb->rb_right)
1608                         rb = rb->rb_right;
1609                 else {
1610                         e = rb_entry(rb, struct ubi_wl_entry, u.rb);
1611
1612                         rb = rb_parent(rb);
1613                         if (rb) {
1614                                 if (rb->rb_left == &e->u.rb)
1615                                         rb->rb_left = NULL;
1616                                 else
1617                                         rb->rb_right = NULL;
1618                         }
1619
1620                         wl_entry_destroy(ubi, e);
1621                 }
1622         }
1623 }
1624
1625 /**
1626  * ubi_thread - UBI background thread.
1627  * @u: the UBI device description object pointer
1628  */
1629 int ubi_thread(void *u)
1630 {
1631         int failures = 0;
1632         struct ubi_device *ubi = u;
1633
1634         ubi_msg(ubi, "background thread \"%s\" started, PID %d",
1635                 ubi->bgt_name, task_pid_nr(current));
1636
1637         set_freezable();
1638         for (;;) {
1639                 int err;
1640
1641                 if (kthread_should_stop())
1642                         break;
1643
1644                 if (try_to_freeze())
1645                         continue;
1646
1647                 spin_lock(&ubi->wl_lock);
1648                 if (list_empty(&ubi->works) || ubi->ro_mode ||
1649                     !ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
1650                         set_current_state(TASK_INTERRUPTIBLE);
1651                         spin_unlock(&ubi->wl_lock);
1652
1653                         /*
1654                          * Check kthread_should_stop() after we set the task
1655                          * state to guarantee that we either see the stop bit
1656                          * and exit or the task state is reset to runnable such
1657                          * that it's not scheduled out indefinitely and detects
1658                          * the stop bit at kthread_should_stop().
1659                          */
1660                         if (kthread_should_stop()) {
1661                                 set_current_state(TASK_RUNNING);
1662                                 break;
1663                         }
1664
1665                         schedule();
1666                         continue;
1667                 }
1668                 spin_unlock(&ubi->wl_lock);
1669
1670                 err = do_work(ubi);
1671                 if (err) {
1672                         ubi_err(ubi, "%s: work failed with error code %d",
1673                                 ubi->bgt_name, err);
1674                         if (failures++ > WL_MAX_FAILURES) {
1675                                 /*
1676                                  * Too many failures, disable the thread and
1677                                  * switch to read-only mode.
1678                                  */
1679                                 ubi_msg(ubi, "%s: %d consecutive failures",
1680                                         ubi->bgt_name, WL_MAX_FAILURES);
1681                                 ubi_ro_mode(ubi);
1682                                 ubi->thread_enabled = 0;
1683                                 continue;
1684                         }
1685                 } else
1686                         failures = 0;
1687
1688                 cond_resched();
1689         }
1690
1691         dbg_wl("background thread \"%s\" is killed", ubi->bgt_name);
1692         ubi->thread_enabled = 0;
1693         return 0;
1694 }
1695
1696 /**
1697  * shutdown_work - shutdown all pending works.
1698  * @ubi: UBI device description object
1699  */
1700 static void shutdown_work(struct ubi_device *ubi)
1701 {
1702         while (!list_empty(&ubi->works)) {
1703                 struct ubi_work *wrk;
1704
1705                 wrk = list_entry(ubi->works.next, struct ubi_work, list);
1706                 list_del(&wrk->list);
1707                 wrk->func(ubi, wrk, 1);
1708                 ubi->works_count -= 1;
1709                 ubi_assert(ubi->works_count >= 0);
1710         }
1711 }
1712
1713 /**
1714  * erase_aeb - erase a PEB given in UBI attach info PEB
1715  * @ubi: UBI device description object
1716  * @aeb: UBI attach info PEB
1717  * @sync: If true, erase synchronously. Otherwise schedule for erasure
1718  */
1719 static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync)
1720 {
1721         struct ubi_wl_entry *e;
1722         int err;
1723
1724         e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1725         if (!e)
1726                 return -ENOMEM;
1727
1728         e->pnum = aeb->pnum;
1729         e->ec = aeb->ec;
1730         ubi->lookuptbl[e->pnum] = e;
1731
1732         if (sync) {
1733                 err = sync_erase(ubi, e, false);
1734                 if (err)
1735                         goto out_free;
1736
1737                 wl_tree_add(e, &ubi->free);
1738                 ubi->free_count++;
1739         } else {
1740                 err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false);
1741                 if (err)
1742                         goto out_free;
1743         }
1744
1745         return 0;
1746
1747 out_free:
1748         wl_entry_destroy(ubi, e);
1749
1750         return err;
1751 }
1752
1753 /**
1754  * ubi_wl_init - initialize the WL sub-system using attaching information.
1755  * @ubi: UBI device description object
1756  * @ai: attaching information
1757  *
1758  * This function returns zero in case of success, and a negative error code in
1759  * case of failure.
1760  */
1761 int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
1762 {
1763         int err, i, reserved_pebs, found_pebs = 0;
1764         struct rb_node *rb1, *rb2;
1765         struct ubi_ainf_volume *av;
1766         struct ubi_ainf_peb *aeb, *tmp;
1767         struct ubi_wl_entry *e;
1768
1769         ubi->used = ubi->erroneous = ubi->free = ubi->scrub = RB_ROOT;
1770         spin_lock_init(&ubi->wl_lock);
1771         mutex_init(&ubi->move_mutex);
1772         init_rwsem(&ubi->work_sem);
1773         ubi->max_ec = ai->max_ec;
1774         INIT_LIST_HEAD(&ubi->works);
1775
1776         sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num);
1777
1778         err = -ENOMEM;
1779         ubi->lookuptbl = kcalloc(ubi->peb_count, sizeof(void *), GFP_KERNEL);
1780         if (!ubi->lookuptbl)
1781                 return err;
1782
1783         for (i = 0; i < UBI_PROT_QUEUE_LEN; i++)
1784                 INIT_LIST_HEAD(&ubi->pq[i]);
1785         ubi->pq_head = 0;
1786
1787         ubi->free_count = 0;
1788         list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
1789                 cond_resched();
1790
1791                 err = erase_aeb(ubi, aeb, false);
1792                 if (err)
1793                         goto out_free;
1794
1795                 found_pebs++;
1796         }
1797
1798         list_for_each_entry(aeb, &ai->free, u.list) {
1799                 cond_resched();
1800
1801                 e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1802                 if (!e) {
1803                         err = -ENOMEM;
1804                         goto out_free;
1805                 }
1806
1807                 e->pnum = aeb->pnum;
1808                 e->ec = aeb->ec;
1809                 ubi_assert(e->ec >= 0);
1810
1811                 wl_tree_add(e, &ubi->free);
1812                 ubi->free_count++;
1813
1814                 ubi->lookuptbl[e->pnum] = e;
1815
1816                 found_pebs++;
1817         }
1818
1819         ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1820                 ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1821                         cond_resched();
1822
1823                         e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
1824                         if (!e) {
1825                                 err = -ENOMEM;
1826                                 goto out_free;
1827                         }
1828
1829                         e->pnum = aeb->pnum;
1830                         e->ec = aeb->ec;
1831                         ubi->lookuptbl[e->pnum] = e;
1832
1833                         if (!aeb->scrub) {
1834                                 dbg_wl("add PEB %d EC %d to the used tree",
1835                                        e->pnum, e->ec);
1836                                 wl_tree_add(e, &ubi->used);
1837                         } else {
1838                                 dbg_wl("add PEB %d EC %d to the scrub tree",
1839                                        e->pnum, e->ec);
1840                                 wl_tree_add(e, &ubi->scrub);
1841                         }
1842
1843                         found_pebs++;
1844                 }
1845         }
1846
1847         list_for_each_entry(aeb, &ai->fastmap, u.list) {
1848                 cond_resched();
1849
1850                 e = ubi_find_fm_block(ubi, aeb->pnum);
1851
1852                 if (e) {
1853                         ubi_assert(!ubi->lookuptbl[e->pnum]);
1854                         ubi->lookuptbl[e->pnum] = e;
1855                 } else {
1856                         bool sync = false;
1857
1858                         /*
1859                          * Usually old Fastmap PEBs are scheduled for erasure
1860                          * and we don't have to care about them but if we face
1861                          * an power cut before scheduling them we need to
1862                          * take care of them here.
1863                          */
1864                         if (ubi->lookuptbl[aeb->pnum])
1865                                 continue;
1866
1867                         /*
1868                          * The fastmap update code might not find a free PEB for
1869                          * writing the fastmap anchor to and then reuses the
1870                          * current fastmap anchor PEB. When this PEB gets erased
1871                          * and a power cut happens before it is written again we
1872                          * must make sure that the fastmap attach code doesn't
1873                          * find any outdated fastmap anchors, hence we erase the
1874                          * outdated fastmap anchor PEBs synchronously here.
1875                          */
1876                         if (aeb->vol_id == UBI_FM_SB_VOLUME_ID)
1877                                 sync = true;
1878
1879                         err = erase_aeb(ubi, aeb, sync);
1880                         if (err)
1881                                 goto out_free;
1882                 }
1883
1884                 found_pebs++;
1885         }
1886
1887         dbg_wl("found %i PEBs", found_pebs);
1888
1889         ubi_assert(ubi->good_peb_count == found_pebs);
1890
1891         reserved_pebs = WL_RESERVED_PEBS;
1892         ubi_fastmap_init(ubi, &reserved_pebs);
1893
1894         if (ubi->avail_pebs < reserved_pebs) {
1895                 ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
1896                         ubi->avail_pebs, reserved_pebs);
1897                 if (ubi->corr_peb_count)
1898                         ubi_err(ubi, "%d PEBs are corrupted and not used",
1899                                 ubi->corr_peb_count);
1900                 err = -ENOSPC;
1901                 goto out_free;
1902         }
1903         ubi->avail_pebs -= reserved_pebs;
1904         ubi->rsvd_pebs += reserved_pebs;
1905
1906         /* Schedule wear-leveling if needed */
1907         err = ensure_wear_leveling(ubi, 0);
1908         if (err)
1909                 goto out_free;
1910
1911 #ifdef CONFIG_MTD_UBI_FASTMAP
1912         if (!ubi->ro_mode && !ubi->fm_disabled)
1913                 ubi_ensure_anchor_pebs(ubi);
1914 #endif
1915         return 0;
1916
1917 out_free:
1918         shutdown_work(ubi);
1919         tree_destroy(ubi, &ubi->used);
1920         tree_destroy(ubi, &ubi->free);
1921         tree_destroy(ubi, &ubi->scrub);
1922         kfree(ubi->lookuptbl);
1923         return err;
1924 }
1925
1926 /**
1927  * protection_queue_destroy - destroy the protection queue.
1928  * @ubi: UBI device description object
1929  */
1930 static void protection_queue_destroy(struct ubi_device *ubi)
1931 {
1932         int i;
1933         struct ubi_wl_entry *e, *tmp;
1934
1935         for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {
1936                 list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {
1937                         list_del(&e->u.list);
1938                         wl_entry_destroy(ubi, e);
1939                 }
1940         }
1941 }
1942
1943 /**
1944  * ubi_wl_close - close the wear-leveling sub-system.
1945  * @ubi: UBI device description object
1946  */
1947 void ubi_wl_close(struct ubi_device *ubi)
1948 {
1949         dbg_wl("close the WL sub-system");
1950         ubi_fastmap_close(ubi);
1951         shutdown_work(ubi);
1952         protection_queue_destroy(ubi);
1953         tree_destroy(ubi, &ubi->used);
1954         tree_destroy(ubi, &ubi->erroneous);
1955         tree_destroy(ubi, &ubi->free);
1956         tree_destroy(ubi, &ubi->scrub);
1957         kfree(ubi->lookuptbl);
1958 }
1959
1960 /**
1961  * self_check_ec - make sure that the erase counter of a PEB is correct.
1962  * @ubi: UBI device description object
1963  * @pnum: the physical eraseblock number to check
1964  * @ec: the erase counter to check
1965  *
1966  * This function returns zero if the erase counter of physical eraseblock @pnum
1967  * is equivalent to @ec, and a negative error code if not or if an error
1968  * occurred.
1969  */
1970 static int self_check_ec(struct ubi_device *ubi, int pnum, int ec)
1971 {
1972         int err;
1973         long long read_ec;
1974         struct ubi_ec_hdr *ec_hdr;
1975
1976         if (!ubi_dbg_chk_gen(ubi))
1977                 return 0;
1978
1979         ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
1980         if (!ec_hdr)
1981                 return -ENOMEM;
1982
1983         err = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
1984         if (err && err != UBI_IO_BITFLIPS) {
1985                 /* The header does not have to exist */
1986                 err = 0;
1987                 goto out_free;
1988         }
1989
1990         read_ec = be64_to_cpu(ec_hdr->ec);
1991         if (ec != read_ec && read_ec - ec > 1) {
1992                 ubi_err(ubi, "self-check failed for PEB %d", pnum);
1993                 ubi_err(ubi, "read EC is %lld, should be %d", read_ec, ec);
1994                 dump_stack();
1995                 err = 1;
1996         } else
1997                 err = 0;
1998
1999 out_free:
2000         kfree(ec_hdr);
2001         return err;
2002 }
2003
2004 /**
2005  * self_check_in_wl_tree - check that wear-leveling entry is in WL RB-tree.
2006  * @ubi: UBI device description object
2007  * @e: the wear-leveling entry to check
2008  * @root: the root of the tree
2009  *
2010  * This function returns zero if @e is in the @root RB-tree and %-EINVAL if it
2011  * is not.
2012  */
2013 static int self_check_in_wl_tree(const struct ubi_device *ubi,
2014                                  struct ubi_wl_entry *e, struct rb_root *root)
2015 {
2016         if (!ubi_dbg_chk_gen(ubi))
2017                 return 0;
2018
2019         if (in_wl_tree(e, root))
2020                 return 0;
2021
2022         ubi_err(ubi, "self-check failed for PEB %d, EC %d, RB-tree %p ",
2023                 e->pnum, e->ec, root);
2024         dump_stack();
2025         return -EINVAL;
2026 }
2027
2028 /**
2029  * self_check_in_pq - check if wear-leveling entry is in the protection
2030  *                        queue.
2031  * @ubi: UBI device description object
2032  * @e: the wear-leveling entry to check
2033  *
2034  * This function returns zero if @e is in @ubi->pq and %-EINVAL if it is not.
2035  */
2036 static int self_check_in_pq(const struct ubi_device *ubi,
2037                             struct ubi_wl_entry *e)
2038 {
2039         if (!ubi_dbg_chk_gen(ubi))
2040                 return 0;
2041
2042         if (in_pq(ubi, e))
2043                 return 0;
2044
2045         ubi_err(ubi, "self-check failed for PEB %d, EC %d, Protect queue",
2046                 e->pnum, e->ec);
2047         dump_stack();
2048         return -EINVAL;
2049 }
2050 #ifndef CONFIG_MTD_UBI_FASTMAP
2051 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
2052 {
2053         struct ubi_wl_entry *e;
2054
2055         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
2056         self_check_in_wl_tree(ubi, e, &ubi->free);
2057         ubi->free_count--;
2058         ubi_assert(ubi->free_count >= 0);
2059         rb_erase(&e->u.rb, &ubi->free);
2060
2061         return e;
2062 }
2063
2064 /**
2065  * produce_free_peb - produce a free physical eraseblock.
2066  * @ubi: UBI device description object
2067  *
2068  * This function tries to make a free PEB by means of synchronous execution of
2069  * pending works. This may be needed if, for example the background thread is
2070  * disabled. Returns zero in case of success and a negative error code in case
2071  * of failure.
2072  */
2073 static int produce_free_peb(struct ubi_device *ubi)
2074 {
2075         int err;
2076
2077         while (!ubi->free.rb_node && ubi->works_count) {
2078                 spin_unlock(&ubi->wl_lock);
2079
2080                 dbg_wl("do one work synchronously");
2081                 err = do_work(ubi);
2082
2083                 spin_lock(&ubi->wl_lock);
2084                 if (err)
2085                         return err;
2086         }
2087
2088         return 0;
2089 }
2090
2091 /**
2092  * ubi_wl_get_peb - get a physical eraseblock.
2093  * @ubi: UBI device description object
2094  *
2095  * This function returns a physical eraseblock in case of success and a
2096  * negative error code in case of failure.
2097  * Returns with ubi->fm_eba_sem held in read mode!
2098  */
2099 int ubi_wl_get_peb(struct ubi_device *ubi)
2100 {
2101         int err;
2102         struct ubi_wl_entry *e;
2103
2104 retry:
2105         down_read(&ubi->fm_eba_sem);
2106         spin_lock(&ubi->wl_lock);
2107         if (!ubi->free.rb_node) {
2108                 if (ubi->works_count == 0) {
2109                         ubi_err(ubi, "no free eraseblocks");
2110                         ubi_assert(list_empty(&ubi->works));
2111                         spin_unlock(&ubi->wl_lock);
2112                         return -ENOSPC;
2113                 }
2114
2115                 err = produce_free_peb(ubi);
2116                 if (err < 0) {
2117                         spin_unlock(&ubi->wl_lock);
2118                         return err;
2119                 }
2120                 spin_unlock(&ubi->wl_lock);
2121                 up_read(&ubi->fm_eba_sem);
2122                 goto retry;
2123
2124         }
2125         e = wl_get_wle(ubi);
2126         prot_queue_add(ubi, e);
2127         spin_unlock(&ubi->wl_lock);
2128
2129         err = ubi_self_check_all_ff(ubi, e->pnum, ubi->vid_hdr_aloffset,
2130                                     ubi->peb_size - ubi->vid_hdr_aloffset);
2131         if (err) {
2132                 ubi_err(ubi, "new PEB %d does not contain all 0xFF bytes", e->pnum);
2133                 return err;
2134         }
2135
2136         return e->pnum;
2137 }
2138 #else
2139 #include "fastmap-wl.c"
2140 #endif