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
 125static int self_check_ec(struct ubi_device *ubi, int pnum, int ec);
 126static int self_check_in_wl_tree(const struct ubi_device *ubi,
 127				 struct ubi_wl_entry *e, struct rb_root *root);
 128static 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 */
 139static 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 */
 175static 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 */
 188static 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 */
 236static 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 */
 275static 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 */
 298static 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 */
 318static 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 */
 353static 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 */
 382static 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 */
 413static 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 */
 438static 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
 485out_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 */
 498static 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	 */
 507repeat:
 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 */
 542static 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 */
 561static 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
 568static 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 */
 583static 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
 610static 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 */
 620static 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
 635static 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 */
 647static 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	 */
 920out_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
 966out_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
 982out_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
 989out_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 */
1007static 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
1065out_cancel:
1066	spin_lock(&ubi->wl_lock);
1067	ubi->wl_scheduled = 0;
1068out_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 */
1083static 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
1199out_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
1209static 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 */
1241int 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
1253retry:
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 */
1333int 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
1339retry:
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 */
1398int 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
1449static 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 */
1482int 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
1586out_resume:
1587	up_write(&ubi->work_sem);
1588out:
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 */
1598static 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 */
1629int 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 */
1700static 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 */
1719static 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
1747out_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 */
1761int 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
1917out_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 */
1930static 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 */
1947void 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 */
1970static 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
1999out_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 */
2013static 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 */
2036static 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
2051static 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 */
2073static 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 */
2099int ubi_wl_get_peb(struct ubi_device *ubi)
2100{
2101	int err;
2102	struct ubi_wl_entry *e;
2103
2104retry:
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