1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Copyright (c) International Business Machines Corp., 2006
   4 *
   5 * Author: Artem Bityutskiy (Битюцкий Артём)
   6 */
   7
   8/*
   9 * UBI attaching sub-system.
  10 *
  11 * This sub-system is responsible for attaching MTD devices and it also
  12 * implements flash media scanning.
  13 *
  14 * The attaching information is represented by a &struct ubi_attach_info'
  15 * object. Information about volumes is represented by &struct ubi_ainf_volume
  16 * objects which are kept in volume RB-tree with root at the @volumes field.
  17 * The RB-tree is indexed by the volume ID.
  18 *
  19 * Logical eraseblocks are represented by &struct ubi_ainf_peb objects. These
  20 * objects are kept in per-volume RB-trees with the root at the corresponding
  21 * &struct ubi_ainf_volume object. To put it differently, we keep an RB-tree of
  22 * per-volume objects and each of these objects is the root of RB-tree of
  23 * per-LEB objects.
  24 *
  25 * Corrupted physical eraseblocks are put to the @corr list, free physical
  26 * eraseblocks are put to the @free list and the physical eraseblock to be
  27 * erased are put to the @erase list.
  28 *
  29 * About corruptions
  30 * ~~~~~~~~~~~~~~~~~
  31 *
  32 * UBI protects EC and VID headers with CRC-32 checksums, so it can detect
  33 * whether the headers are corrupted or not. Sometimes UBI also protects the
  34 * data with CRC-32, e.g., when it executes the atomic LEB change operation, or
  35 * when it moves the contents of a PEB for wear-leveling purposes.
  36 *
  37 * UBI tries to distinguish between 2 types of corruptions.
  38 *
  39 * 1. Corruptions caused by power cuts. These are expected corruptions and UBI
  40 * tries to handle them gracefully, without printing too many warnings and
  41 * error messages. The idea is that we do not lose important data in these
  42 * cases - we may lose only the data which were being written to the media just
  43 * before the power cut happened, and the upper layers (e.g., UBIFS) are
  44 * supposed to handle such data losses (e.g., by using the FS journal).
  45 *
  46 * When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like
  47 * the reason is a power cut, UBI puts this PEB to the @erase list, and all
  48 * PEBs in the @erase list are scheduled for erasure later.
  49 *
  50 * 2. Unexpected corruptions which are not caused by power cuts. During
  51 * attaching, such PEBs are put to the @corr list and UBI preserves them.
  52 * Obviously, this lessens the amount of available PEBs, and if at some  point
  53 * UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs
  54 * about such PEBs every time the MTD device is attached.
  55 *
  56 * However, it is difficult to reliably distinguish between these types of
  57 * corruptions and UBI's strategy is as follows (in case of attaching by
  58 * scanning). UBI assumes corruption type 2 if the VID header is corrupted and
  59 * the data area does not contain all 0xFFs, and there were no bit-flips or
  60 * integrity errors (e.g., ECC errors in case of NAND) while reading the data
  61 * area.  Otherwise UBI assumes corruption type 1. So the decision criteria
  62 * are as follows.
  63 *   o If the data area contains only 0xFFs, there are no data, and it is safe
  64 *     to just erase this PEB - this is corruption type 1.
  65 *   o If the data area has bit-flips or data integrity errors (ECC errors on
  66 *     NAND), it is probably a PEB which was being erased when power cut
  67 *     happened, so this is corruption type 1. However, this is just a guess,
  68 *     which might be wrong.
  69 *   o Otherwise this is corruption type 2.
  70 */
  71
  72#include <linux/err.h>
  73#include <linux/slab.h>
  74#include <linux/crc32.h>
  75#include <linux/math64.h>
  76#include <linux/random.h>
  77#include "ubi.h"
  78
  79static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai);
  80
  81#define AV_FIND		BIT(0)
  82#define AV_ADD		BIT(1)
  83#define AV_FIND_OR_ADD	(AV_FIND | AV_ADD)
  84
  85/**
  86 * find_or_add_av - internal function to find a volume, add a volume or do
  87 *		    both (find and add if missing).
  88 * @ai: attaching information
  89 * @vol_id: the requested volume ID
  90 * @flags: a combination of the %AV_FIND and %AV_ADD flags describing the
  91 *	   expected operation. If only %AV_ADD is set, -EEXIST is returned
  92 *	   if the volume already exists. If only %AV_FIND is set, NULL is
  93 *	   returned if the volume does not exist. And if both flags are
  94 *	   set, the helper first tries to find an existing volume, and if
  95 *	   it does not exist it creates a new one.
  96 * @created: in value used to inform the caller whether it"s a newly created
  97 *	     volume or not.
  98 *
  99 * This function returns a pointer to a volume description or an ERR_PTR if
 100 * the operation failed. It can also return NULL if only %AV_FIND is set and
 101 * the volume does not exist.
 102 */
 103static struct ubi_ainf_volume *find_or_add_av(struct ubi_attach_info *ai,
 104					      int vol_id, unsigned int flags,
 105					      bool *created)
 106{
 107	struct ubi_ainf_volume *av;
 108	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
 109
 110	/* Walk the volume RB-tree to look if this volume is already present */
 111	while (*p) {
 112		parent = *p;
 113		av = rb_entry(parent, struct ubi_ainf_volume, rb);
 114
 115		if (vol_id == av->vol_id) {
 116			*created = false;
 117
 118			if (!(flags & AV_FIND))
 119				return ERR_PTR(-EEXIST);
 120
 121			return av;
 122		}
 123
 124		if (vol_id > av->vol_id)
 125			p = &(*p)->rb_left;
 126		else
 127			p = &(*p)->rb_right;
 128	}
 129
 130	if (!(flags & AV_ADD))
 131		return NULL;
 132
 133	/* The volume is absent - add it */
 134	av = kzalloc(sizeof(*av), GFP_KERNEL);
 135	if (!av)
 136		return ERR_PTR(-ENOMEM);
 137
 138	av->vol_id = vol_id;
 139
 140	if (vol_id > ai->highest_vol_id)
 141		ai->highest_vol_id = vol_id;
 142
 143	rb_link_node(&av->rb, parent, p);
 144	rb_insert_color(&av->rb, &ai->volumes);
 145	ai->vols_found += 1;
 146	*created = true;
 147	dbg_bld("added volume %d", vol_id);
 148	return av;
 149}
 150
 151/**
 152 * ubi_find_or_add_av - search for a volume in the attaching information and
 153 *			add one if it does not exist.
 154 * @ai: attaching information
 155 * @vol_id: the requested volume ID
 156 * @created: whether the volume has been created or not
 157 *
 158 * This function returns a pointer to the new volume description or an
 159 * ERR_PTR if the operation failed.
 160 */
 161static struct ubi_ainf_volume *ubi_find_or_add_av(struct ubi_attach_info *ai,
 162						  int vol_id, bool *created)
 163{
 164	return find_or_add_av(ai, vol_id, AV_FIND_OR_ADD, created);
 165}
 166
 167/**
 168 * ubi_alloc_aeb - allocate an aeb element
 169 * @ai: attaching information
 170 * @pnum: physical eraseblock number
 171 * @ec: erase counter of the physical eraseblock
 172 *
 173 * Allocate an aeb object and initialize the pnum and ec information.
 174 * vol_id and lnum are set to UBI_UNKNOWN, and the other fields are
 175 * initialized to zero.
 176 * Note that the element is not added in any list or RB tree.
 177 */
 178struct ubi_ainf_peb *ubi_alloc_aeb(struct ubi_attach_info *ai, int pnum,
 179				   int ec)
 180{
 181	struct ubi_ainf_peb *aeb;
 182
 183	aeb = kmem_cache_zalloc(ai->aeb_slab_cache, GFP_KERNEL);
 184	if (!aeb)
 185		return NULL;
 186
 187	aeb->pnum = pnum;
 188	aeb->ec = ec;
 189	aeb->vol_id = UBI_UNKNOWN;
 190	aeb->lnum = UBI_UNKNOWN;
 191
 192	return aeb;
 193}
 194
 195/**
 196 * ubi_free_aeb - free an aeb element
 197 * @ai: attaching information
 198 * @aeb: the element to free
 199 *
 200 * Free an aeb object. The caller must have removed the element from any list
 201 * or RB tree.
 202 */
 203void ubi_free_aeb(struct ubi_attach_info *ai, struct ubi_ainf_peb *aeb)
 204{
 205	kmem_cache_free(ai->aeb_slab_cache, aeb);
 206}
 207
 208/**
 209 * add_to_list - add physical eraseblock to a list.
 210 * @ai: attaching information
 211 * @pnum: physical eraseblock number to add
 212 * @vol_id: the last used volume id for the PEB
 213 * @lnum: the last used LEB number for the PEB
 214 * @ec: erase counter of the physical eraseblock
 215 * @to_head: if not zero, add to the head of the list
 216 * @list: the list to add to
 217 *
 218 * This function allocates a 'struct ubi_ainf_peb' object for physical
 219 * eraseblock @pnum and adds it to the "free", "erase", or "alien" lists.
 220 * It stores the @lnum and @vol_id alongside, which can both be
 221 * %UBI_UNKNOWN if they are not available, not readable, or not assigned.
 222 * If @to_head is not zero, PEB will be added to the head of the list, which
 223 * basically means it will be processed first later. E.g., we add corrupted
 224 * PEBs (corrupted due to power cuts) to the head of the erase list to make
 225 * sure we erase them first and get rid of corruptions ASAP. This function
 226 * returns zero in case of success and a negative error code in case of
 227 * failure.
 228 */
 229static int add_to_list(struct ubi_attach_info *ai, int pnum, int vol_id,
 230		       int lnum, int ec, int to_head, struct list_head *list)
 231{
 232	struct ubi_ainf_peb *aeb;
 233
 234	if (list == &ai->free) {
 235		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
 236	} else if (list == &ai->erase) {
 237		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
 238	} else if (list == &ai->alien) {
 239		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
 240		ai->alien_peb_count += 1;
 241	} else
 242		BUG();
 243
 244	aeb = ubi_alloc_aeb(ai, pnum, ec);
 245	if (!aeb)
 246		return -ENOMEM;
 247
 248	aeb->vol_id = vol_id;
 249	aeb->lnum = lnum;
 250	if (to_head)
 251		list_add(&aeb->u.list, list);
 252	else
 253		list_add_tail(&aeb->u.list, list);
 254	return 0;
 255}
 256
 257/**
 258 * add_corrupted - add a corrupted physical eraseblock.
 259 * @ai: attaching information
 260 * @pnum: physical eraseblock number to add
 261 * @ec: erase counter of the physical eraseblock
 262 *
 263 * This function allocates a 'struct ubi_ainf_peb' object for a corrupted
 264 * physical eraseblock @pnum and adds it to the 'corr' list.  The corruption
 265 * was presumably not caused by a power cut. Returns zero in case of success
 266 * and a negative error code in case of failure.
 267 */
 268static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
 269{
 270	struct ubi_ainf_peb *aeb;
 271
 272	dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
 273
 274	aeb = ubi_alloc_aeb(ai, pnum, ec);
 275	if (!aeb)
 276		return -ENOMEM;
 277
 278	ai->corr_peb_count += 1;
 279	list_add(&aeb->u.list, &ai->corr);
 280	return 0;
 281}
 282
 283/**
 284 * add_fastmap - add a Fastmap related physical eraseblock.
 285 * @ai: attaching information
 286 * @pnum: physical eraseblock number the VID header came from
 287 * @vid_hdr: the volume identifier header
 288 * @ec: erase counter of the physical eraseblock
 289 *
 290 * This function allocates a 'struct ubi_ainf_peb' object for a Fastamp
 291 * physical eraseblock @pnum and adds it to the 'fastmap' list.
 292 * Such blocks can be Fastmap super and data blocks from both the most
 293 * recent Fastmap we're attaching from or from old Fastmaps which will
 294 * be erased.
 295 */
 296static int add_fastmap(struct ubi_attach_info *ai, int pnum,
 297		       struct ubi_vid_hdr *vid_hdr, int ec)
 298{
 299	struct ubi_ainf_peb *aeb;
 300
 301	aeb = ubi_alloc_aeb(ai, pnum, ec);
 302	if (!aeb)
 303		return -ENOMEM;
 304
 305	aeb->vol_id = be32_to_cpu(vid_hdr->vol_id);
 306	aeb->sqnum = be64_to_cpu(vid_hdr->sqnum);
 307	list_add(&aeb->u.list, &ai->fastmap);
 308
 309	dbg_bld("add to fastmap list: PEB %d, vol_id %d, sqnum: %llu", pnum,
 310		aeb->vol_id, aeb->sqnum);
 311
 312	return 0;
 313}
 314
 315/**
 316 * validate_vid_hdr - check volume identifier header.
 317 * @ubi: UBI device description object
 318 * @vid_hdr: the volume identifier header to check
 319 * @av: information about the volume this logical eraseblock belongs to
 320 * @pnum: physical eraseblock number the VID header came from
 321 *
 322 * This function checks that data stored in @vid_hdr is consistent. Returns
 323 * non-zero if an inconsistency was found and zero if not.
 324 *
 325 * Note, UBI does sanity check of everything it reads from the flash media.
 326 * Most of the checks are done in the I/O sub-system. Here we check that the
 327 * information in the VID header is consistent to the information in other VID
 328 * headers of the same volume.
 329 */
 330static int validate_vid_hdr(const struct ubi_device *ubi,
 331			    const struct ubi_vid_hdr *vid_hdr,
 332			    const struct ubi_ainf_volume *av, int pnum)
 333{
 334	int vol_type = vid_hdr->vol_type;
 335	int vol_id = be32_to_cpu(vid_hdr->vol_id);
 336	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
 337	int data_pad = be32_to_cpu(vid_hdr->data_pad);
 338
 339	if (av->leb_count != 0) {
 340		int av_vol_type;
 341
 342		/*
 343		 * This is not the first logical eraseblock belonging to this
 344		 * volume. Ensure that the data in its VID header is consistent
 345		 * to the data in previous logical eraseblock headers.
 346		 */
 347
 348		if (vol_id != av->vol_id) {
 349			ubi_err(ubi, "inconsistent vol_id");
 350			goto bad;
 351		}
 352
 353		if (av->vol_type == UBI_STATIC_VOLUME)
 354			av_vol_type = UBI_VID_STATIC;
 355		else
 356			av_vol_type = UBI_VID_DYNAMIC;
 357
 358		if (vol_type != av_vol_type) {
 359			ubi_err(ubi, "inconsistent vol_type");
 360			goto bad;
 361		}
 362
 363		if (used_ebs != av->used_ebs) {
 364			ubi_err(ubi, "inconsistent used_ebs");
 365			goto bad;
 366		}
 367
 368		if (data_pad != av->data_pad) {
 369			ubi_err(ubi, "inconsistent data_pad");
 370			goto bad;
 371		}
 372	}
 373
 374	return 0;
 375
 376bad:
 377	ubi_err(ubi, "inconsistent VID header at PEB %d", pnum);
 378	ubi_dump_vid_hdr(vid_hdr);
 379	ubi_dump_av(av);
 380	return -EINVAL;
 381}
 382
 383/**
 384 * add_volume - add volume to the attaching information.
 385 * @ai: attaching information
 386 * @vol_id: ID of the volume to add
 387 * @pnum: physical eraseblock number
 388 * @vid_hdr: volume identifier header
 389 *
 390 * If the volume corresponding to the @vid_hdr logical eraseblock is already
 391 * present in the attaching information, this function does nothing. Otherwise
 392 * it adds corresponding volume to the attaching information. Returns a pointer
 393 * to the allocated "av" object in case of success and a negative error code in
 394 * case of failure.
 395 */
 396static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
 397					  int vol_id, int pnum,
 398					  const struct ubi_vid_hdr *vid_hdr)
 399{
 400	struct ubi_ainf_volume *av;
 401	bool created;
 402
 403	ubi_assert(vol_id == be32_to_cpu(vid_hdr->vol_id));
 404
 405	av = ubi_find_or_add_av(ai, vol_id, &created);
 406	if (IS_ERR(av) || !created)
 407		return av;
 408
 409	av->used_ebs = be32_to_cpu(vid_hdr->used_ebs);
 410	av->data_pad = be32_to_cpu(vid_hdr->data_pad);
 411	av->compat = vid_hdr->compat;
 412	av->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
 413							    : UBI_STATIC_VOLUME;
 414
 415	return av;
 416}
 417
 418/**
 419 * ubi_compare_lebs - find out which logical eraseblock is newer.
 420 * @ubi: UBI device description object
 421 * @aeb: first logical eraseblock to compare
 422 * @pnum: physical eraseblock number of the second logical eraseblock to
 423 * compare
 424 * @vid_hdr: volume identifier header of the second logical eraseblock
 425 *
 426 * This function compares 2 copies of a LEB and informs which one is newer. In
 427 * case of success this function returns a positive value, in case of failure, a
 428 * negative error code is returned. The success return codes use the following
 429 * bits:
 430 *     o bit 0 is cleared: the first PEB (described by @aeb) is newer than the
 431 *       second PEB (described by @pnum and @vid_hdr);
 432 *     o bit 0 is set: the second PEB is newer;
 433 *     o bit 1 is cleared: no bit-flips were detected in the newer LEB;
 434 *     o bit 1 is set: bit-flips were detected in the newer LEB;
 435 *     o bit 2 is cleared: the older LEB is not corrupted;
 436 *     o bit 2 is set: the older LEB is corrupted.
 437 */
 438int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
 439			int pnum, const struct ubi_vid_hdr *vid_hdr)
 440{
 441	int len, err, second_is_newer, bitflips = 0, corrupted = 0;
 442	uint32_t data_crc, crc;
 443	struct ubi_vid_io_buf *vidb = NULL;
 444	unsigned long long sqnum2 = be64_to_cpu(vid_hdr->sqnum);
 445
 446	if (sqnum2 == aeb->sqnum) {
 447		/*
 448		 * This must be a really ancient UBI image which has been
 449		 * created before sequence numbers support has been added. At
 450		 * that times we used 32-bit LEB versions stored in logical
 451		 * eraseblocks. That was before UBI got into mainline. We do not
 452		 * support these images anymore. Well, those images still work,
 453		 * but only if no unclean reboots happened.
 454		 */
 455		ubi_err(ubi, "unsupported on-flash UBI format");
 456		return -EINVAL;
 457	}
 458
 459	/* Obviously the LEB with lower sequence counter is older */
 460	second_is_newer = (sqnum2 > aeb->sqnum);
 461
 462	/*
 463	 * Now we know which copy is newer. If the copy flag of the PEB with
 464	 * newer version is not set, then we just return, otherwise we have to
 465	 * check data CRC. For the second PEB we already have the VID header,
 466	 * for the first one - we'll need to re-read it from flash.
 467	 *
 468	 * Note: this may be optimized so that we wouldn't read twice.
 469	 */
 470
 471	if (second_is_newer) {
 472		if (!vid_hdr->copy_flag) {
 473			/* It is not a copy, so it is newer */
 474			dbg_bld("second PEB %d is newer, copy_flag is unset",
 475				pnum);
 476			return 1;
 477		}
 478	} else {
 479		if (!aeb->copy_flag) {
 480			/* It is not a copy, so it is newer */
 481			dbg_bld("first PEB %d is newer, copy_flag is unset",
 482				pnum);
 483			return bitflips << 1;
 484		}
 485
 486		vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
 487		if (!vidb)
 488			return -ENOMEM;
 489
 490		pnum = aeb->pnum;
 491		err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
 492		if (err) {
 493			if (err == UBI_IO_BITFLIPS)
 494				bitflips = 1;
 495			else {
 496				ubi_err(ubi, "VID of PEB %d header is bad, but it was OK earlier, err %d",
 497					pnum, err);
 498				if (err > 0)
 499					err = -EIO;
 500
 501				goto out_free_vidh;
 502			}
 503		}
 504
 505		vid_hdr = ubi_get_vid_hdr(vidb);
 506	}
 507
 508	/* Read the data of the copy and check the CRC */
 509
 510	len = be32_to_cpu(vid_hdr->data_size);
 511
 512	mutex_lock(&ubi->buf_mutex);
 513	err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, len);
 514	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
 515		goto out_unlock;
 516
 517	data_crc = be32_to_cpu(vid_hdr->data_crc);
 518	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, len);
 519	if (crc != data_crc) {
 520		dbg_bld("PEB %d CRC error: calculated %#08x, must be %#08x",
 521			pnum, crc, data_crc);
 522		corrupted = 1;
 523		bitflips = 0;
 524		second_is_newer = !second_is_newer;
 525	} else {
 526		dbg_bld("PEB %d CRC is OK", pnum);
 527		bitflips |= !!err;
 528	}
 529	mutex_unlock(&ubi->buf_mutex);
 530
 531	ubi_free_vid_buf(vidb);
 532
 533	if (second_is_newer)
 534		dbg_bld("second PEB %d is newer, copy_flag is set", pnum);
 535	else
 536		dbg_bld("first PEB %d is newer, copy_flag is set", pnum);
 537
 538	return second_is_newer | (bitflips << 1) | (corrupted << 2);
 539
 540out_unlock:
 541	mutex_unlock(&ubi->buf_mutex);
 542out_free_vidh:
 543	ubi_free_vid_buf(vidb);
 544	return err;
 545}
 546
 547/**
 548 * ubi_add_to_av - add used physical eraseblock to the attaching information.
 549 * @ubi: UBI device description object
 550 * @ai: attaching information
 551 * @pnum: the physical eraseblock number
 552 * @ec: erase counter
 553 * @vid_hdr: the volume identifier header
 554 * @bitflips: if bit-flips were detected when this physical eraseblock was read
 555 *
 556 * This function adds information about a used physical eraseblock to the
 557 * 'used' tree of the corresponding volume. The function is rather complex
 558 * because it has to handle cases when this is not the first physical
 559 * eraseblock belonging to the same logical eraseblock, and the newer one has
 560 * to be picked, while the older one has to be dropped. This function returns
 561 * zero in case of success and a negative error code in case of failure.
 562 */
 563int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
 564		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips)
 565{
 566	int err, vol_id, lnum;
 567	unsigned long long sqnum;
 568	struct ubi_ainf_volume *av;
 569	struct ubi_ainf_peb *aeb;
 570	struct rb_node **p, *parent = NULL;
 571
 572	vol_id = be32_to_cpu(vid_hdr->vol_id);
 573	lnum = be32_to_cpu(vid_hdr->lnum);
 574	sqnum = be64_to_cpu(vid_hdr->sqnum);
 575
 576	dbg_bld("PEB %d, LEB %d:%d, EC %d, sqnum %llu, bitflips %d",
 577		pnum, vol_id, lnum, ec, sqnum, bitflips);
 578
 579	av = add_volume(ai, vol_id, pnum, vid_hdr);
 580	if (IS_ERR(av))
 581		return PTR_ERR(av);
 582
 583	if (ai->max_sqnum < sqnum)
 584		ai->max_sqnum = sqnum;
 585
 586	/*
 587	 * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
 588	 * if this is the first instance of this logical eraseblock or not.
 589	 */
 590	p = &av->root.rb_node;
 591	while (*p) {
 592		int cmp_res;
 593
 594		parent = *p;
 595		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
 596		if (lnum != aeb->lnum) {
 597			if (lnum < aeb->lnum)
 598				p = &(*p)->rb_left;
 599			else
 600				p = &(*p)->rb_right;
 601			continue;
 602		}
 603
 604		/*
 605		 * There is already a physical eraseblock describing the same
 606		 * logical eraseblock present.
 607		 */
 608
 609		dbg_bld("this LEB already exists: PEB %d, sqnum %llu, EC %d",
 610			aeb->pnum, aeb->sqnum, aeb->ec);
 611
 612		/*
 613		 * Make sure that the logical eraseblocks have different
 614		 * sequence numbers. Otherwise the image is bad.
 615		 *
 616		 * However, if the sequence number is zero, we assume it must
 617		 * be an ancient UBI image from the era when UBI did not have
 618		 * sequence numbers. We still can attach these images, unless
 619		 * there is a need to distinguish between old and new
 620		 * eraseblocks, in which case we'll refuse the image in
 621		 * 'ubi_compare_lebs()'. In other words, we attach old clean
 622		 * images, but refuse attaching old images with duplicated
 623		 * logical eraseblocks because there was an unclean reboot.
 624		 */
 625		if (aeb->sqnum == sqnum && sqnum != 0) {
 626			ubi_err(ubi, "two LEBs with same sequence number %llu",
 627				sqnum);
 628			ubi_dump_aeb(aeb, 0);
 629			ubi_dump_vid_hdr(vid_hdr);
 630			return -EINVAL;
 631		}
 632
 633		/*
 634		 * Now we have to drop the older one and preserve the newer
 635		 * one.
 636		 */
 637		cmp_res = ubi_compare_lebs(ubi, aeb, pnum, vid_hdr);
 638		if (cmp_res < 0)
 639			return cmp_res;
 640
 641		if (cmp_res & 1) {
 642			/*
 643			 * This logical eraseblock is newer than the one
 644			 * found earlier.
 645			 */
 646			err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
 647			if (err)
 648				return err;
 649
 650			err = add_to_list(ai, aeb->pnum, aeb->vol_id,
 651					  aeb->lnum, aeb->ec, cmp_res & 4,
 652					  &ai->erase);
 653			if (err)
 654				return err;
 655
 656			aeb->ec = ec;
 657			aeb->pnum = pnum;
 658			aeb->vol_id = vol_id;
 659			aeb->lnum = lnum;
 660			aeb->scrub = ((cmp_res & 2) || bitflips);
 661			aeb->copy_flag = vid_hdr->copy_flag;
 662			aeb->sqnum = sqnum;
 663
 664			if (av->highest_lnum == lnum)
 665				av->last_data_size =
 666					be32_to_cpu(vid_hdr->data_size);
 667
 668			return 0;
 669		} else {
 670			/*
 671			 * This logical eraseblock is older than the one found
 672			 * previously.
 673			 */
 674			return add_to_list(ai, pnum, vol_id, lnum, ec,
 675					   cmp_res & 4, &ai->erase);
 676		}
 677	}
 678
 679	/*
 680	 * We've met this logical eraseblock for the first time, add it to the
 681	 * attaching information.
 682	 */
 683
 684	err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
 685	if (err)
 686		return err;
 687
 688	aeb = ubi_alloc_aeb(ai, pnum, ec);
 689	if (!aeb)
 690		return -ENOMEM;
 691
 692	aeb->vol_id = vol_id;
 693	aeb->lnum = lnum;
 694	aeb->scrub = bitflips;
 695	aeb->copy_flag = vid_hdr->copy_flag;
 696	aeb->sqnum = sqnum;
 697
 698	if (av->highest_lnum <= lnum) {
 699		av->highest_lnum = lnum;
 700		av->last_data_size = be32_to_cpu(vid_hdr->data_size);
 701	}
 702
 703	av->leb_count += 1;
 704	rb_link_node(&aeb->u.rb, parent, p);
 705	rb_insert_color(&aeb->u.rb, &av->root);
 706	return 0;
 707}
 708
 709/**
 710 * ubi_add_av - add volume to the attaching information.
 711 * @ai: attaching information
 712 * @vol_id: the requested volume ID
 713 *
 714 * This function returns a pointer to the new volume description or an
 715 * ERR_PTR if the operation failed.
 716 */
 717struct ubi_ainf_volume *ubi_add_av(struct ubi_attach_info *ai, int vol_id)
 718{
 719	bool created;
 720
 721	return find_or_add_av(ai, vol_id, AV_ADD, &created);
 722}
 723
 724/**
 725 * ubi_find_av - find volume in the attaching information.
 726 * @ai: attaching information
 727 * @vol_id: the requested volume ID
 728 *
 729 * This function returns a pointer to the volume description or %NULL if there
 730 * are no data about this volume in the attaching information.
 731 */
 732struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
 733				    int vol_id)
 734{
 735	bool created;
 736
 737	return find_or_add_av((struct ubi_attach_info *)ai, vol_id, AV_FIND,
 738			      &created);
 739}
 740
 741static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
 742		       struct list_head *list);
 743
 744/**
 745 * ubi_remove_av - delete attaching information about a volume.
 746 * @ai: attaching information
 747 * @av: the volume attaching information to delete
 748 */
 749void ubi_remove_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
 750{
 751	dbg_bld("remove attaching information about volume %d", av->vol_id);
 752
 753	rb_erase(&av->rb, &ai->volumes);
 754	destroy_av(ai, av, &ai->erase);
 755	ai->vols_found -= 1;
 756}
 757
 758/**
 759 * early_erase_peb - erase a physical eraseblock.
 760 * @ubi: UBI device description object
 761 * @ai: attaching information
 762 * @pnum: physical eraseblock number to erase;
 763 * @ec: erase counter value to write (%UBI_UNKNOWN if it is unknown)
 764 *
 765 * This function erases physical eraseblock 'pnum', and writes the erase
 766 * counter header to it. This function should only be used on UBI device
 767 * initialization stages, when the EBA sub-system had not been yet initialized.
 768 * This function returns zero in case of success and a negative error code in
 769 * case of failure.
 770 */
 771static int early_erase_peb(struct ubi_device *ubi,
 772			   const struct ubi_attach_info *ai, int pnum, int ec)
 773{
 774	int err;
 775	struct ubi_ec_hdr *ec_hdr;
 776
 777	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
 778		/*
 779		 * Erase counter overflow. Upgrade UBI and use 64-bit
 780		 * erase counters internally.
 781		 */
 782		ubi_err(ubi, "erase counter overflow at PEB %d, EC %d",
 783			pnum, ec);
 784		return -EINVAL;
 785	}
 786
 787	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
 788	if (!ec_hdr)
 789		return -ENOMEM;
 790
 791	ec_hdr->ec = cpu_to_be64(ec);
 792
 793	err = ubi_io_sync_erase(ubi, pnum, 0);
 794	if (err < 0)
 795		goto out_free;
 796
 797	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
 798
 799out_free:
 800	kfree(ec_hdr);
 801	return err;
 802}
 803
 804/**
 805 * ubi_early_get_peb - get a free physical eraseblock.
 806 * @ubi: UBI device description object
 807 * @ai: attaching information
 808 *
 809 * This function returns a free physical eraseblock. It is supposed to be
 810 * called on the UBI initialization stages when the wear-leveling sub-system is
 811 * not initialized yet. This function picks a physical eraseblocks from one of
 812 * the lists, writes the EC header if it is needed, and removes it from the
 813 * list.
 814 *
 815 * This function returns a pointer to the "aeb" of the found free PEB in case
 816 * of success and an error code in case of failure.
 817 */
 818struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
 819				       struct ubi_attach_info *ai)
 820{
 821	int err = 0;
 822	struct ubi_ainf_peb *aeb, *tmp_aeb;
 823
 824	if (!list_empty(&ai->free)) {
 825		aeb = list_entry(ai->free.next, struct ubi_ainf_peb, u.list);
 826		list_del(&aeb->u.list);
 827		dbg_bld("return free PEB %d, EC %d", aeb->pnum, aeb->ec);
 828		return aeb;
 829	}
 830
 831	/*
 832	 * We try to erase the first physical eraseblock from the erase list
 833	 * and pick it if we succeed, or try to erase the next one if not. And
 834	 * so forth. We don't want to take care about bad eraseblocks here -
 835	 * they'll be handled later.
 836	 */
 837	list_for_each_entry_safe(aeb, tmp_aeb, &ai->erase, u.list) {
 838		if (aeb->ec == UBI_UNKNOWN)
 839			aeb->ec = ai->mean_ec;
 840
 841		err = early_erase_peb(ubi, ai, aeb->pnum, aeb->ec+1);
 842		if (err)
 843			continue;
 844
 845		aeb->ec += 1;
 846		list_del(&aeb->u.list);
 847		dbg_bld("return PEB %d, EC %d", aeb->pnum, aeb->ec);
 848		return aeb;
 849	}
 850
 851	ubi_err(ubi, "no free eraseblocks");
 852	return ERR_PTR(-ENOSPC);
 853}
 854
 855/**
 856 * check_corruption - check the data area of PEB.
 857 * @ubi: UBI device description object
 858 * @vid_hdr: the (corrupted) VID header of this PEB
 859 * @pnum: the physical eraseblock number to check
 860 *
 861 * This is a helper function which is used to distinguish between VID header
 862 * corruptions caused by power cuts and other reasons. If the PEB contains only
 863 * 0xFF bytes in the data area, the VID header is most probably corrupted
 864 * because of a power cut (%0 is returned in this case). Otherwise, it was
 865 * probably corrupted for some other reasons (%1 is returned in this case). A
 866 * negative error code is returned if a read error occurred.
 867 *
 868 * If the corruption reason was a power cut, UBI can safely erase this PEB.
 869 * Otherwise, it should preserve it to avoid possibly destroying important
 870 * information.
 871 */
 872static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
 873			    int pnum)
 874{
 875	int err;
 876
 877	mutex_lock(&ubi->buf_mutex);
 878	memset(ubi->peb_buf, 0x00, ubi->leb_size);
 879
 880	err = ubi_io_read(ubi, ubi->peb_buf, pnum, ubi->leb_start,
 881			  ubi->leb_size);
 882	if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err)) {
 883		/*
 884		 * Bit-flips or integrity errors while reading the data area.
 885		 * It is difficult to say for sure what type of corruption is
 886		 * this, but presumably a power cut happened while this PEB was
 887		 * erased, so it became unstable and corrupted, and should be
 888		 * erased.
 889		 */
 890		err = 0;
 891		goto out_unlock;
 892	}
 893
 894	if (err)
 895		goto out_unlock;
 896
 897	if (ubi_check_pattern(ubi->peb_buf, 0xFF, ubi->leb_size))
 898		goto out_unlock;
 899
 900	ubi_err(ubi, "PEB %d contains corrupted VID header, and the data does not contain all 0xFF",
 901		pnum);
 902	ubi_err(ubi, "this may be a non-UBI PEB or a severe VID header corruption which requires manual inspection");
 903	ubi_dump_vid_hdr(vid_hdr);
 904	pr_err("hexdump of PEB %d offset %d, length %d",
 905	       pnum, ubi->leb_start, ubi->leb_size);
 906	ubi_dbg_print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
 907			       ubi->peb_buf, ubi->leb_size, 1);
 908	err = 1;
 909
 910out_unlock:
 911	mutex_unlock(&ubi->buf_mutex);
 912	return err;
 913}
 914
 915static bool vol_ignored(int vol_id)
 916{
 917	switch (vol_id) {
 918		case UBI_LAYOUT_VOLUME_ID:
 919		return true;
 920	}
 921
 922#ifdef CONFIG_MTD_UBI_FASTMAP
 923	return ubi_is_fm_vol(vol_id);
 924#else
 925	return false;
 926#endif
 927}
 928
 929/**
 930 * scan_peb - scan and process UBI headers of a PEB.
 931 * @ubi: UBI device description object
 932 * @ai: attaching information
 933 * @pnum: the physical eraseblock number
 934 * @fast: true if we're scanning for a Fastmap
 935 *
 936 * This function reads UBI headers of PEB @pnum, checks them, and adds
 937 * information about this PEB to the corresponding list or RB-tree in the
 938 * "attaching info" structure. Returns zero if the physical eraseblock was
 939 * successfully handled and a negative error code in case of failure.
 940 */
 941static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 942		    int pnum, bool fast)
 943{
 944	struct ubi_ec_hdr *ech = ai->ech;
 945	struct ubi_vid_io_buf *vidb = ai->vidb;
 946	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
 947	long long ec;
 948	int err, bitflips = 0, vol_id = -1, ec_err = 0;
 949
 950	dbg_bld("scan PEB %d", pnum);
 951
 952	/* Skip bad physical eraseblocks */
 953	err = ubi_io_is_bad(ubi, pnum);
 954	if (err < 0)
 955		return err;
 956	else if (err) {
 957		ai->bad_peb_count += 1;
 958		return 0;
 959	}
 960
 961	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
 962	if (err < 0)
 963		return err;
 964	switch (err) {
 965	case 0:
 966		break;
 967	case UBI_IO_BITFLIPS:
 968		bitflips = 1;
 969		break;
 970	case UBI_IO_FF:
 971		ai->empty_peb_count += 1;
 972		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
 973				   UBI_UNKNOWN, 0, &ai->erase);
 974	case UBI_IO_FF_BITFLIPS:
 975		ai->empty_peb_count += 1;
 976		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
 977				   UBI_UNKNOWN, 1, &ai->erase);
 978	case UBI_IO_BAD_HDR_EBADMSG:
 979	case UBI_IO_BAD_HDR:
 980		/*
 981		 * We have to also look at the VID header, possibly it is not
 982		 * corrupted. Set %bitflips flag in order to make this PEB be
 983		 * moved and EC be re-created.
 984		 */
 985		ec_err = err;
 986		ec = UBI_UNKNOWN;
 987		bitflips = 1;
 988		break;
 989	default:
 990		ubi_err(ubi, "'ubi_io_read_ec_hdr()' returned unknown code %d",
 991			err);
 992		return -EINVAL;
 993	}
 994
 995	if (!ec_err) {
 996		int image_seq;
 997
 998		/* Make sure UBI version is OK */
 999		if (ech->version != UBI_VERSION) {
1000			ubi_err(ubi, "this UBI version is %d, image version is %d",
1001				UBI_VERSION, (int)ech->version);
1002			return -EINVAL;
1003		}
1004
1005		ec = be64_to_cpu(ech->ec);
1006		if (ec > UBI_MAX_ERASECOUNTER) {
1007			/*
1008			 * Erase counter overflow. The EC headers have 64 bits
1009			 * reserved, but we anyway make use of only 31 bit
1010			 * values, as this seems to be enough for any existing
1011			 * flash. Upgrade UBI and use 64-bit erase counters
1012			 * internally.
1013			 */
1014			ubi_err(ubi, "erase counter overflow, max is %d",
1015				UBI_MAX_ERASECOUNTER);
1016			ubi_dump_ec_hdr(ech);
1017			return -EINVAL;
1018		}
1019
1020		/*
1021		 * Make sure that all PEBs have the same image sequence number.
1022		 * This allows us to detect situations when users flash UBI
1023		 * images incorrectly, so that the flash has the new UBI image
1024		 * and leftovers from the old one. This feature was added
1025		 * relatively recently, and the sequence number was always
1026		 * zero, because old UBI implementations always set it to zero.
1027		 * For this reasons, we do not panic if some PEBs have zero
1028		 * sequence number, while other PEBs have non-zero sequence
1029		 * number.
1030		 */
1031		image_seq = be32_to_cpu(ech->image_seq);
1032		if (!ubi->image_seq)
1033			ubi->image_seq = image_seq;
1034		if (image_seq && ubi->image_seq != image_seq) {
1035			ubi_err(ubi, "bad image sequence number %d in PEB %d, expected %d",
1036				image_seq, pnum, ubi->image_seq);
1037			ubi_dump_ec_hdr(ech);
1038			return -EINVAL;
1039		}
1040	}
1041
1042	/* OK, we've done with the EC header, let's look at the VID header */
1043
1044	err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
1045	if (err < 0)
1046		return err;
1047	switch (err) {
1048	case 0:
1049		break;
1050	case UBI_IO_BITFLIPS:
1051		bitflips = 1;
1052		break;
1053	case UBI_IO_BAD_HDR_EBADMSG:
1054		if (ec_err == UBI_IO_BAD_HDR_EBADMSG)
1055			/*
1056			 * Both EC and VID headers are corrupted and were read
1057			 * with data integrity error, probably this is a bad
1058			 * PEB, bit it is not marked as bad yet. This may also
1059			 * be a result of power cut during erasure.
1060			 */
1061			ai->maybe_bad_peb_count += 1;
1062		fallthrough;
1063	case UBI_IO_BAD_HDR:
1064			/*
1065			 * If we're facing a bad VID header we have to drop *all*
1066			 * Fastmap data structures we find. The most recent Fastmap
1067			 * could be bad and therefore there is a chance that we attach
1068			 * from an old one. On a fine MTD stack a PEB must not render
1069			 * bad all of a sudden, but the reality is different.
1070			 * So, let's be paranoid and help finding the root cause by
1071			 * falling back to scanning mode instead of attaching with a
1072			 * bad EBA table and cause data corruption which is hard to
1073			 * analyze.
1074			 */
1075			if (fast)
1076				ai->force_full_scan = 1;
1077
1078		if (ec_err)
1079			/*
1080			 * Both headers are corrupted. There is a possibility
1081			 * that this a valid UBI PEB which has corresponding
1082			 * LEB, but the headers are corrupted. However, it is
1083			 * impossible to distinguish it from a PEB which just
1084			 * contains garbage because of a power cut during erase
1085			 * operation. So we just schedule this PEB for erasure.
1086			 *
1087			 * Besides, in case of NOR flash, we deliberately
1088			 * corrupt both headers because NOR flash erasure is
1089			 * slow and can start from the end.
1090			 */
1091			err = 0;
1092		else
1093			/*
1094			 * The EC was OK, but the VID header is corrupted. We
1095			 * have to check what is in the data area.
1096			 */
1097			err = check_corruption(ubi, vidh, pnum);
1098
1099		if (err < 0)
1100			return err;
1101		else if (!err)
1102			/* This corruption is caused by a power cut */
1103			err = add_to_list(ai, pnum, UBI_UNKNOWN,
1104					  UBI_UNKNOWN, ec, 1, &ai->erase);
1105		else
1106			/* This is an unexpected corruption */
1107			err = add_corrupted(ai, pnum, ec);
1108		if (err)
1109			return err;
1110		goto adjust_mean_ec;
1111	case UBI_IO_FF_BITFLIPS:
1112		err = add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
1113				  ec, 1, &ai->erase);
1114		if (err)
1115			return err;
1116		goto adjust_mean_ec;
1117	case UBI_IO_FF:
1118		if (ec_err || bitflips)
1119			err = add_to_list(ai, pnum, UBI_UNKNOWN,
1120					  UBI_UNKNOWN, ec, 1, &ai->erase);
1121		else
1122			err = add_to_list(ai, pnum, UBI_UNKNOWN,
1123					  UBI_UNKNOWN, ec, 0, &ai->free);
1124		if (err)
1125			return err;
1126		goto adjust_mean_ec;
1127	default:
1128		ubi_err(ubi, "'ubi_io_read_vid_hdr()' returned unknown code %d",
1129			err);
1130		return -EINVAL;
1131	}
1132
1133	vol_id = be32_to_cpu(vidh->vol_id);
1134	if (vol_id > UBI_MAX_VOLUMES && !vol_ignored(vol_id)) {
1135		int lnum = be32_to_cpu(vidh->lnum);
1136
1137		/* Unsupported internal volume */
1138		switch (vidh->compat) {
1139		case UBI_COMPAT_DELETE:
1140			ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
1141				vol_id, lnum);
1142
1143			err = add_to_list(ai, pnum, vol_id, lnum,
1144					  ec, 1, &ai->erase);
1145			if (err)
1146				return err;
1147			return 0;
1148
1149		case UBI_COMPAT_RO:
1150			ubi_msg(ubi, "read-only compatible internal volume %d:%d found, switch to read-only mode",
1151				vol_id, lnum);
1152			ubi->ro_mode = 1;
1153			break;
1154
1155		case UBI_COMPAT_PRESERVE:
1156			ubi_msg(ubi, "\"preserve\" compatible internal volume %d:%d found",
1157				vol_id, lnum);
1158			err = add_to_list(ai, pnum, vol_id, lnum,
1159					  ec, 0, &ai->alien);
1160			if (err)
1161				return err;
1162			return 0;
1163
1164		case UBI_COMPAT_REJECT:
1165			ubi_err(ubi, "incompatible internal volume %d:%d found",
1166				vol_id, lnum);
1167			return -EINVAL;
1168		}
1169	}
1170
1171	if (ec_err)
1172		ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
1173			 pnum);
1174
1175	if (ubi_is_fm_vol(vol_id))
1176		err = add_fastmap(ai, pnum, vidh, ec);
1177	else
1178		err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
1179
1180	if (err)
1181		return err;
1182
1183adjust_mean_ec:
1184	if (!ec_err) {
1185		ai->ec_sum += ec;
1186		ai->ec_count += 1;
1187		if (ec > ai->max_ec)
1188			ai->max_ec = ec;
1189		if (ec < ai->min_ec)
1190			ai->min_ec = ec;
1191	}
1192
1193	return 0;
1194}
1195
1196/**
1197 * late_analysis - analyze the overall situation with PEB.
1198 * @ubi: UBI device description object
1199 * @ai: attaching information
1200 *
1201 * This is a helper function which takes a look what PEBs we have after we
1202 * gather information about all of them ("ai" is compete). It decides whether
1203 * the flash is empty and should be formatted of whether there are too many
1204 * corrupted PEBs and we should not attach this MTD device. Returns zero if we
1205 * should proceed with attaching the MTD device, and %-EINVAL if we should not.
1206 */
1207static int late_analysis(struct ubi_device *ubi, struct ubi_attach_info *ai)
1208{
1209	struct ubi_ainf_peb *aeb;
1210	int max_corr, peb_count;
1211
1212	peb_count = ubi->peb_count - ai->bad_peb_count - ai->alien_peb_count;
1213	max_corr = peb_count / 20 ?: 8;
1214
1215	/*
1216	 * Few corrupted PEBs is not a problem and may be just a result of
1217	 * unclean reboots. However, many of them may indicate some problems
1218	 * with the flash HW or driver.
1219	 */
1220	if (ai->corr_peb_count) {
1221		ubi_err(ubi, "%d PEBs are corrupted and preserved",
1222			ai->corr_peb_count);
1223		pr_err("Corrupted PEBs are:");
1224		list_for_each_entry(aeb, &ai->corr, u.list)
1225			pr_cont(" %d", aeb->pnum);
1226		pr_cont("\n");
1227
1228		/*
1229		 * If too many PEBs are corrupted, we refuse attaching,
1230		 * otherwise, only print a warning.
1231		 */
1232		if (ai->corr_peb_count >= max_corr) {
1233			ubi_err(ubi, "too many corrupted PEBs, refusing");
1234			return -EINVAL;
1235		}
1236	}
1237
1238	if (ai->empty_peb_count + ai->maybe_bad_peb_count == peb_count) {
1239		/*
1240		 * All PEBs are empty, or almost all - a couple PEBs look like
1241		 * they may be bad PEBs which were not marked as bad yet.
1242		 *
1243		 * This piece of code basically tries to distinguish between
1244		 * the following situations:
1245		 *
1246		 * 1. Flash is empty, but there are few bad PEBs, which are not
1247		 *    marked as bad so far, and which were read with error. We
1248		 *    want to go ahead and format this flash. While formatting,
1249		 *    the faulty PEBs will probably be marked as bad.
1250		 *
1251		 * 2. Flash contains non-UBI data and we do not want to format
1252		 *    it and destroy possibly important information.
1253		 */
1254		if (ai->maybe_bad_peb_count <= 2) {
1255			ai->is_empty = 1;
1256			ubi_msg(ubi, "empty MTD device detected");
1257			get_random_bytes(&ubi->image_seq,
1258					 sizeof(ubi->image_seq));
1259		} else {
1260			ubi_err(ubi, "MTD device is not UBI-formatted and possibly contains non-UBI data - refusing it");
1261			return -EINVAL;
1262		}
1263
1264	}
1265
1266	return 0;
1267}
1268
1269/**
1270 * destroy_av - free volume attaching information.
1271 * @av: volume attaching information
1272 * @ai: attaching information
1273 * @list: put the aeb elements in there if !NULL, otherwise free them
1274 *
1275 * This function destroys the volume attaching information.
1276 */
1277static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
1278		       struct list_head *list)
1279{
1280	struct ubi_ainf_peb *aeb;
1281	struct rb_node *this = av->root.rb_node;
1282
1283	while (this) {
1284		if (this->rb_left)
1285			this = this->rb_left;
1286		else if (this->rb_right)
1287			this = this->rb_right;
1288		else {
1289			aeb = rb_entry(this, struct ubi_ainf_peb, u.rb);
1290			this = rb_parent(this);
1291			if (this) {
1292				if (this->rb_left == &aeb->u.rb)
1293					this->rb_left = NULL;
1294				else
1295					this->rb_right = NULL;
1296			}
1297
1298			if (list)
1299				list_add_tail(&aeb->u.list, list);
1300			else
1301				ubi_free_aeb(ai, aeb);
1302		}
1303	}
1304	kfree(av);
1305}
1306
1307/**
1308 * destroy_ai - destroy attaching information.
1309 * @ai: attaching information
1310 */
1311static void destroy_ai(struct ubi_attach_info *ai)
1312{
1313	struct ubi_ainf_peb *aeb, *aeb_tmp;
1314	struct ubi_ainf_volume *av;
1315	struct rb_node *rb;
1316
1317	list_for_each_entry_safe(aeb, aeb_tmp, &ai->alien, u.list) {
1318		list_del(&aeb->u.list);
1319		ubi_free_aeb(ai, aeb);
1320	}
1321	list_for_each_entry_safe(aeb, aeb_tmp, &ai->erase, u.list) {
1322		list_del(&aeb->u.list);
1323		ubi_free_aeb(ai, aeb);
1324	}
1325	list_for_each_entry_safe(aeb, aeb_tmp, &ai->corr, u.list) {
1326		list_del(&aeb->u.list);
1327		ubi_free_aeb(ai, aeb);
1328	}
1329	list_for_each_entry_safe(aeb, aeb_tmp, &ai->free, u.list) {
1330		list_del(&aeb->u.list);
1331		ubi_free_aeb(ai, aeb);
1332	}
1333	list_for_each_entry_safe(aeb, aeb_tmp, &ai->fastmap, u.list) {
1334		list_del(&aeb->u.list);
1335		ubi_free_aeb(ai, aeb);
1336	}
1337
1338	/* Destroy the volume RB-tree */
1339	rb = ai->volumes.rb_node;
1340	while (rb) {
1341		if (rb->rb_left)
1342			rb = rb->rb_left;
1343		else if (rb->rb_right)
1344			rb = rb->rb_right;
1345		else {
1346			av = rb_entry(rb, struct ubi_ainf_volume, rb);
1347
1348			rb = rb_parent(rb);
1349			if (rb) {
1350				if (rb->rb_left == &av->rb)
1351					rb->rb_left = NULL;
1352				else
1353					rb->rb_right = NULL;
1354			}
1355
1356			destroy_av(ai, av, NULL);
1357		}
1358	}
1359
1360	kmem_cache_destroy(ai->aeb_slab_cache);
1361	kfree(ai);
1362}
1363
1364/**
1365 * scan_all - scan entire MTD device.
1366 * @ubi: UBI device description object
1367 * @ai: attach info object
1368 * @start: start scanning at this PEB
1369 *
1370 * This function does full scanning of an MTD device and returns complete
1371 * information about it in form of a "struct ubi_attach_info" object. In case
1372 * of failure, an error code is returned.
1373 */
1374static int scan_all(struct ubi_device *ubi, struct ubi_attach_info *ai,
1375		    int start)
1376{
1377	int err, pnum;
1378	struct rb_node *rb1, *rb2;
1379	struct ubi_ainf_volume *av;
1380	struct ubi_ainf_peb *aeb;
1381
1382	err = -ENOMEM;
1383
1384	ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
1385	if (!ai->ech)
1386		return err;
1387
1388	ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
1389	if (!ai->vidb)
1390		goto out_ech;
1391
1392	for (pnum = start; pnum < ubi->peb_count; pnum++) {
1393		cond_resched();
1394
1395		dbg_gen("process PEB %d", pnum);
1396		err = scan_peb(ubi, ai, pnum, false);
1397		if (err < 0)
1398			goto out_vidh;
1399	}
1400
1401	ubi_msg(ubi, "scanning is finished");
1402
1403	/* Calculate mean erase counter */
1404	if (ai->ec_count)
1405		ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
1406
1407	err = late_analysis(ubi, ai);
1408	if (err)
1409		goto out_vidh;
1410
1411	/*
1412	 * In case of unknown erase counter we use the mean erase counter
1413	 * value.
1414	 */
1415	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1416		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
1417			if (aeb->ec == UBI_UNKNOWN)
1418				aeb->ec = ai->mean_ec;
1419	}
1420
1421	list_for_each_entry(aeb, &ai->free, u.list) {
1422		if (aeb->ec == UBI_UNKNOWN)
1423			aeb->ec = ai->mean_ec;
1424	}
1425
1426	list_for_each_entry(aeb, &ai->corr, u.list)
1427		if (aeb->ec == UBI_UNKNOWN)
1428			aeb->ec = ai->mean_ec;
1429
1430	list_for_each_entry(aeb, &ai->erase, u.list)
1431		if (aeb->ec == UBI_UNKNOWN)
1432			aeb->ec = ai->mean_ec;
1433
1434	err = self_check_ai(ubi, ai);
1435	if (err)
1436		goto out_vidh;
1437
1438	ubi_free_vid_buf(ai->vidb);
1439	kfree(ai->ech);
1440
1441	return 0;
1442
1443out_vidh:
1444	ubi_free_vid_buf(ai->vidb);
1445out_ech:
1446	kfree(ai->ech);
1447	return err;
1448}
1449
1450static struct ubi_attach_info *alloc_ai(void)
1451{
1452	struct ubi_attach_info *ai;
1453
1454	ai = kzalloc(sizeof(struct ubi_attach_info), GFP_KERNEL);
1455	if (!ai)
1456		return ai;
1457
1458	INIT_LIST_HEAD(&ai->corr);
1459	INIT_LIST_HEAD(&ai->free);
1460	INIT_LIST_HEAD(&ai->erase);
1461	INIT_LIST_HEAD(&ai->alien);
1462	INIT_LIST_HEAD(&ai->fastmap);
1463	ai->volumes = RB_ROOT;
1464	ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
1465					       sizeof(struct ubi_ainf_peb),
1466					       0, 0, NULL);
1467	if (!ai->aeb_slab_cache) {
1468		kfree(ai);
1469		ai = NULL;
1470	}
1471
1472	return ai;
1473}
1474
1475#ifdef CONFIG_MTD_UBI_FASTMAP
1476
1477/**
1478 * scan_fast - try to find a fastmap and attach from it.
1479 * @ubi: UBI device description object
1480 * @ai: attach info object
1481 *
1482 * Returns 0 on success, negative return values indicate an internal
1483 * error.
1484 * UBI_NO_FASTMAP denotes that no fastmap was found.
1485 * UBI_BAD_FASTMAP denotes that the found fastmap was invalid.
1486 */
1487static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
1488{
1489	int err, pnum;
1490	struct ubi_attach_info *scan_ai;
1491
1492	err = -ENOMEM;
1493
1494	scan_ai = alloc_ai();
1495	if (!scan_ai)
1496		goto out;
1497
1498	scan_ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
1499	if (!scan_ai->ech)
1500		goto out_ai;
1501
1502	scan_ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
1503	if (!scan_ai->vidb)
1504		goto out_ech;
1505
1506	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
1507		cond_resched();
1508
1509		dbg_gen("process PEB %d", pnum);
1510		err = scan_peb(ubi, scan_ai, pnum, true);
1511		if (err < 0)
1512			goto out_vidh;
1513	}
1514
1515	ubi_free_vid_buf(scan_ai->vidb);
1516	kfree(scan_ai->ech);
1517
1518	if (scan_ai->force_full_scan)
1519		err = UBI_NO_FASTMAP;
1520	else
1521		err = ubi_scan_fastmap(ubi, *ai, scan_ai);
1522
1523	if (err) {
1524		/*
1525		 * Didn't attach via fastmap, do a full scan but reuse what
1526		 * we've aready scanned.
1527		 */
1528		destroy_ai(*ai);
1529		*ai = scan_ai;
1530	} else
1531		destroy_ai(scan_ai);
1532
1533	return err;
1534
1535out_vidh:
1536	ubi_free_vid_buf(scan_ai->vidb);
1537out_ech:
1538	kfree(scan_ai->ech);
1539out_ai:
1540	destroy_ai(scan_ai);
1541out:
1542	return err;
1543}
1544
1545#endif
1546
1547/**
1548 * ubi_attach - attach an MTD device.
1549 * @ubi: UBI device descriptor
1550 * @force_scan: if set to non-zero attach by scanning
1551 *
1552 * This function returns zero in case of success and a negative error code in
1553 * case of failure.
1554 */
1555int ubi_attach(struct ubi_device *ubi, int force_scan)
1556{
1557	int err;
1558	struct ubi_attach_info *ai;
1559
1560	ai = alloc_ai();
1561	if (!ai)
1562		return -ENOMEM;
1563
1564#ifdef CONFIG_MTD_UBI_FASTMAP
1565	/* On small flash devices we disable fastmap in any case. */
1566	if ((int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd) <= UBI_FM_MAX_START) {
1567		ubi->fm_disabled = 1;
1568		force_scan = 1;
1569	}
1570
1571	if (force_scan)
1572		err = scan_all(ubi, ai, 0);
1573	else {
1574		err = scan_fast(ubi, &ai);
1575		if (err > 0 || mtd_is_eccerr(err)) {
1576			if (err != UBI_NO_FASTMAP) {
1577				destroy_ai(ai);
1578				ai = alloc_ai();
1579				if (!ai)
1580					return -ENOMEM;
1581
1582				err = scan_all(ubi, ai, 0);
1583			} else {
1584				err = scan_all(ubi, ai, UBI_FM_MAX_START);
1585			}
1586		}
1587	}
1588#else
1589	err = scan_all(ubi, ai, 0);
1590#endif
1591	if (err)
1592		goto out_ai;
1593
1594	ubi->bad_peb_count = ai->bad_peb_count;
1595	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
1596	ubi->corr_peb_count = ai->corr_peb_count;
1597	ubi->max_ec = ai->max_ec;
1598	ubi->mean_ec = ai->mean_ec;
1599	dbg_gen("max. sequence number:       %llu", ai->max_sqnum);
1600
1601	err = ubi_read_volume_table(ubi, ai);
1602	if (err)
1603		goto out_ai;
1604
1605	err = ubi_wl_init(ubi, ai);
1606	if (err)
1607		goto out_vtbl;
1608
1609	err = ubi_eba_init(ubi, ai);
1610	if (err)
1611		goto out_wl;
1612
1613#ifdef CONFIG_MTD_UBI_FASTMAP
1614	if (ubi->fm && ubi_dbg_chk_fastmap(ubi)) {
1615		struct ubi_attach_info *scan_ai;
1616
1617		scan_ai = alloc_ai();
1618		if (!scan_ai) {
1619			err = -ENOMEM;
1620			goto out_wl;
1621		}
1622
1623		err = scan_all(ubi, scan_ai, 0);
1624		if (err) {
1625			destroy_ai(scan_ai);
1626			goto out_wl;
1627		}
1628
1629		err = self_check_eba(ubi, ai, scan_ai);
1630		destroy_ai(scan_ai);
1631
1632		if (err)
1633			goto out_wl;
1634	}
1635#endif
1636
1637	destroy_ai(ai);
1638	return 0;
1639
1640out_wl:
1641	ubi_wl_close(ubi);
1642out_vtbl:
1643	ubi_free_all_volumes(ubi);
1644	vfree(ubi->vtbl);
1645out_ai:
1646	destroy_ai(ai);
1647	return err;
1648}
1649
1650/**
1651 * self_check_ai - check the attaching information.
1652 * @ubi: UBI device description object
1653 * @ai: attaching information
1654 *
1655 * This function returns zero if the attaching information is all right, and a
1656 * negative error code if not or if an error occurred.
1657 */
1658static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai)
1659{
1660	struct ubi_vid_io_buf *vidb = ai->vidb;
1661	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
1662	int pnum, err, vols_found = 0;
1663	struct rb_node *rb1, *rb2;
1664	struct ubi_ainf_volume *av;
1665	struct ubi_ainf_peb *aeb, *last_aeb;
1666	uint8_t *buf;
1667
1668	if (!ubi_dbg_chk_gen(ubi))
1669		return 0;
1670
1671	/*
1672	 * At first, check that attaching information is OK.
1673	 */
1674	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1675		int leb_count = 0;
1676
1677		cond_resched();
1678
1679		vols_found += 1;
1680
1681		if (ai->is_empty) {
1682			ubi_err(ubi, "bad is_empty flag");
1683			goto bad_av;
1684		}
1685
1686		if (av->vol_id < 0 || av->highest_lnum < 0 ||
1687		    av->leb_count < 0 || av->vol_type < 0 || av->used_ebs < 0 ||
1688		    av->data_pad < 0 || av->last_data_size < 0) {
1689			ubi_err(ubi, "negative values");
1690			goto bad_av;
1691		}
1692
1693		if (av->vol_id >= UBI_MAX_VOLUMES &&
1694		    av->vol_id < UBI_INTERNAL_VOL_START) {
1695			ubi_err(ubi, "bad vol_id");
1696			goto bad_av;
1697		}
1698
1699		if (av->vol_id > ai->highest_vol_id) {
1700			ubi_err(ubi, "highest_vol_id is %d, but vol_id %d is there",
1701				ai->highest_vol_id, av->vol_id);
1702			goto out;
1703		}
1704
1705		if (av->vol_type != UBI_DYNAMIC_VOLUME &&
1706		    av->vol_type != UBI_STATIC_VOLUME) {
1707			ubi_err(ubi, "bad vol_type");
1708			goto bad_av;
1709		}
1710
1711		if (av->data_pad > ubi->leb_size / 2) {
1712			ubi_err(ubi, "bad data_pad");
1713			goto bad_av;
1714		}
1715
1716		last_aeb = NULL;
1717		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1718			cond_resched();
1719
1720			last_aeb = aeb;
1721			leb_count += 1;
1722
1723			if (aeb->pnum < 0 || aeb->ec < 0) {
1724				ubi_err(ubi, "negative values");
1725				goto bad_aeb;
1726			}
1727
1728			if (aeb->ec < ai->min_ec) {
1729				ubi_err(ubi, "bad ai->min_ec (%d), %d found",
1730					ai->min_ec, aeb->ec);
1731				goto bad_aeb;
1732			}
1733
1734			if (aeb->ec > ai->max_ec) {
1735				ubi_err(ubi, "bad ai->max_ec (%d), %d found",
1736					ai->max_ec, aeb->ec);
1737				goto bad_aeb;
1738			}
1739
1740			if (aeb->pnum >= ubi->peb_count) {
1741				ubi_err(ubi, "too high PEB number %d, total PEBs %d",
1742					aeb->pnum, ubi->peb_count);
1743				goto bad_aeb;
1744			}
1745
1746			if (av->vol_type == UBI_STATIC_VOLUME) {
1747				if (aeb->lnum >= av->used_ebs) {
1748					ubi_err(ubi, "bad lnum or used_ebs");
1749					goto bad_aeb;
1750				}
1751			} else {
1752				if (av->used_ebs != 0) {
1753					ubi_err(ubi, "non-zero used_ebs");
1754					goto bad_aeb;
1755				}
1756			}
1757
1758			if (aeb->lnum > av->highest_lnum) {
1759				ubi_err(ubi, "incorrect highest_lnum or lnum");
1760				goto bad_aeb;
1761			}
1762		}
1763
1764		if (av->leb_count != leb_count) {
1765			ubi_err(ubi, "bad leb_count, %d objects in the tree",
1766				leb_count);
1767			goto bad_av;
1768		}
1769
1770		if (!last_aeb)
1771			continue;
1772
1773		aeb = last_aeb;
1774
1775		if (aeb->lnum != av->highest_lnum) {
1776			ubi_err(ubi, "bad highest_lnum");
1777			goto bad_aeb;
1778		}
1779	}
1780
1781	if (vols_found != ai->vols_found) {
1782		ubi_err(ubi, "bad ai->vols_found %d, should be %d",
1783			ai->vols_found, vols_found);
1784		goto out;
1785	}
1786
1787	/* Check that attaching information is correct */
1788	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1789		last_aeb = NULL;
1790		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1791			int vol_type;
1792
1793			cond_resched();
1794
1795			last_aeb = aeb;
1796
1797			err = ubi_io_read_vid_hdr(ubi, aeb->pnum, vidb, 1);
1798			if (err && err != UBI_IO_BITFLIPS) {
1799				ubi_err(ubi, "VID header is not OK (%d)",
1800					err);
1801				if (err > 0)
1802					err = -EIO;
1803				return err;
1804			}
1805
1806			vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
1807				   UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
1808			if (av->vol_type != vol_type) {
1809				ubi_err(ubi, "bad vol_type");
1810				goto bad_vid_hdr;
1811			}
1812
1813			if (aeb->sqnum != be64_to_cpu(vidh->sqnum)) {
1814				ubi_err(ubi, "bad sqnum %llu", aeb->sqnum);
1815				goto bad_vid_hdr;
1816			}
1817
1818			if (av->vol_id != be32_to_cpu(vidh->vol_id)) {
1819				ubi_err(ubi, "bad vol_id %d", av->vol_id);
1820				goto bad_vid_hdr;
1821			}
1822
1823			if (av->compat != vidh->compat) {
1824				ubi_err(ubi, "bad compat %d", vidh->compat);
1825				goto bad_vid_hdr;
1826			}
1827
1828			if (aeb->lnum != be32_to_cpu(vidh->lnum)) {
1829				ubi_err(ubi, "bad lnum %d", aeb->lnum);
1830				goto bad_vid_hdr;
1831			}
1832
1833			if (av->used_ebs != be32_to_cpu(vidh->used_ebs)) {
1834				ubi_err(ubi, "bad used_ebs %d", av->used_ebs);
1835				goto bad_vid_hdr;
1836			}
1837
1838			if (av->data_pad != be32_to_cpu(vidh->data_pad)) {
1839				ubi_err(ubi, "bad data_pad %d", av->data_pad);
1840				goto bad_vid_hdr;
1841			}
1842		}
1843
1844		if (!last_aeb)
1845			continue;
1846
1847		if (av->highest_lnum != be32_to_cpu(vidh->lnum)) {
1848			ubi_err(ubi, "bad highest_lnum %d", av->highest_lnum);
1849			goto bad_vid_hdr;
1850		}
1851
1852		if (av->last_data_size != be32_to_cpu(vidh->data_size)) {
1853			ubi_err(ubi, "bad last_data_size %d",
1854				av->last_data_size);
1855			goto bad_vid_hdr;
1856		}
1857	}
1858
1859	/*
1860	 * Make sure that all the physical eraseblocks are in one of the lists
1861	 * or trees.
1862	 */
1863	buf = kzalloc(ubi->peb_count, GFP_KERNEL);
1864	if (!buf)
1865		return -ENOMEM;
1866
1867	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
1868		err = ubi_io_is_bad(ubi, pnum);
1869		if (err < 0) {
1870			kfree(buf);
1871			return err;
1872		} else if (err)
1873			buf[pnum] = 1;
1874	}
1875
1876	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
1877		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
1878			buf[aeb->pnum] = 1;
1879
1880	list_for_each_entry(aeb, &ai->free, u.list)
1881		buf[aeb->pnum] = 1;
1882
1883	list_for_each_entry(aeb, &ai->corr, u.list)
1884		buf[aeb->pnum] = 1;
1885
1886	list_for_each_entry(aeb, &ai->erase, u.list)
1887		buf[aeb->pnum] = 1;
1888
1889	list_for_each_entry(aeb, &ai->alien, u.list)
1890		buf[aeb->pnum] = 1;
1891
1892	err = 0;
1893	for (pnum = 0; pnum < ubi->peb_count; pnum++)
1894		if (!buf[pnum]) {
1895			ubi_err(ubi, "PEB %d is not referred", pnum);
1896			err = 1;
1897		}
1898
1899	kfree(buf);
1900	if (err)
1901		goto out;
1902	return 0;
1903
1904bad_aeb:
1905	ubi_err(ubi, "bad attaching information about LEB %d", aeb->lnum);
1906	ubi_dump_aeb(aeb, 0);
1907	ubi_dump_av(av);
1908	goto out;
1909
1910bad_av:
1911	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
1912	ubi_dump_av(av);
1913	goto out;
1914
1915bad_vid_hdr:
1916	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
1917	ubi_dump_av(av);
1918	ubi_dump_vid_hdr(vidh);
1919
1920out:
1921	dump_stack();
1922	return -EINVAL;
1923}