Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1923 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
new file mode 100644
index 000000000..ae5abe492
--- /dev/null
+++ b/drivers/mtd/ubi/attach.c
@@ -0,0 +1,1923 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * UBI attaching sub-system.
+ *
+ * This sub-system is responsible for attaching MTD devices and it also
+ * implements flash media scanning.
+ *
+ * The attaching information is represented by a &struct ubi_attach_info'
+ * object. Information about volumes is represented by &struct ubi_ainf_volume
+ * objects which are kept in volume RB-tree with root at the @volumes field.
+ * The RB-tree is indexed by the volume ID.
+ *
+ * Logical eraseblocks are represented by &struct ubi_ainf_peb objects. These
+ * objects are kept in per-volume RB-trees with the root at the corresponding
+ * &struct ubi_ainf_volume object. To put it differently, we keep an RB-tree of
+ * per-volume objects and each of these objects is the root of RB-tree of
+ * per-LEB objects.
+ *
+ * Corrupted physical eraseblocks are put to the @corr list, free physical
+ * eraseblocks are put to the @free list and the physical eraseblock to be
+ * erased are put to the @erase list.
+ *
+ * About corruptions
+ * ~~~~~~~~~~~~~~~~~
+ *
+ * UBI protects EC and VID headers with CRC-32 checksums, so it can detect
+ * whether the headers are corrupted or not. Sometimes UBI also protects the
+ * data with CRC-32, e.g., when it executes the atomic LEB change operation, or
+ * when it moves the contents of a PEB for wear-leveling purposes.
+ *
+ * UBI tries to distinguish between 2 types of corruptions.
+ *
+ * 1. Corruptions caused by power cuts. These are expected corruptions and UBI
+ * tries to handle them gracefully, without printing too many warnings and
+ * error messages. The idea is that we do not lose important data in these
+ * cases - we may lose only the data which were being written to the media just
+ * before the power cut happened, and the upper layers (e.g., UBIFS) are
+ * supposed to handle such data losses (e.g., by using the FS journal).
+ *
+ * When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like
+ * the reason is a power cut, UBI puts this PEB to the @erase list, and all
+ * PEBs in the @erase list are scheduled for erasure later.
+ *
+ * 2. Unexpected corruptions which are not caused by power cuts. During
+ * attaching, such PEBs are put to the @corr list and UBI preserves them.
+ * Obviously, this lessens the amount of available PEBs, and if at some  point
+ * UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs
+ * about such PEBs every time the MTD device is attached.
+ *
+ * However, it is difficult to reliably distinguish between these types of
+ * corruptions and UBI's strategy is as follows (in case of attaching by
+ * scanning). UBI assumes corruption type 2 if the VID header is corrupted and
+ * the data area does not contain all 0xFFs, and there were no bit-flips or
+ * integrity errors (e.g., ECC errors in case of NAND) while reading the data
+ * area.  Otherwise UBI assumes corruption type 1. So the decision criteria
+ * are as follows.
+ *   o If the data area contains only 0xFFs, there are no data, and it is safe
+ *     to just erase this PEB - this is corruption type 1.
+ *   o If the data area has bit-flips or data integrity errors (ECC errors on
+ *     NAND), it is probably a PEB which was being erased when power cut
+ *     happened, so this is corruption type 1. However, this is just a guess,
+ *     which might be wrong.
+ *   o Otherwise this is corruption type 2.
+ */
+
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/math64.h>
+#include <linux/random.h>
+#include "ubi.h"
+
+static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai);
+
+#define AV_FIND		BIT(0)
+#define AV_ADD		BIT(1)
+#define AV_FIND_OR_ADD	(AV_FIND | AV_ADD)
+
+/**
+ * find_or_add_av - internal function to find a volume, add a volume or do
+ *		    both (find and add if missing).
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ * @flags: a combination of the %AV_FIND and %AV_ADD flags describing the
+ *	   expected operation. If only %AV_ADD is set, -EEXIST is returned
+ *	   if the volume already exists. If only %AV_FIND is set, NULL is
+ *	   returned if the volume does not exist. And if both flags are
+ *	   set, the helper first tries to find an existing volume, and if
+ *	   it does not exist it creates a new one.
+ * @created: in value used to inform the caller whether it"s a newly created
+ *	     volume or not.
+ *
+ * This function returns a pointer to a volume description or an ERR_PTR if
+ * the operation failed. It can also return NULL if only %AV_FIND is set and
+ * the volume does not exist.
+ */
+static struct ubi_ainf_volume *find_or_add_av(struct ubi_attach_info *ai,
+					      int vol_id, unsigned int flags,
+					      bool *created)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+
+	/* Walk the volume RB-tree to look if this volume is already present */
+	while (*p) {
+		parent = *p;
+		av = rb_entry(parent, struct ubi_ainf_volume, rb);
+
+		if (vol_id == av->vol_id) {
+			*created = false;
+
+			if (!(flags & AV_FIND))
+				return ERR_PTR(-EEXIST);
+
+			return av;
+		}
+
+		if (vol_id > av->vol_id)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	if (!(flags & AV_ADD))
+		return NULL;
+
+	/* The volume is absent - add it */
+	av = kzalloc(sizeof(*av), GFP_KERNEL);
+	if (!av)
+		return ERR_PTR(-ENOMEM);
+
+	av->vol_id = vol_id;
+
+	if (vol_id > ai->highest_vol_id)
+		ai->highest_vol_id = vol_id;
+
+	rb_link_node(&av->rb, parent, p);
+	rb_insert_color(&av->rb, &ai->volumes);
+	ai->vols_found += 1;
+	*created = true;
+	dbg_bld("added volume %d", vol_id);
+	return av;
+}
+
+/**
+ * ubi_find_or_add_av - search for a volume in the attaching information and
+ *			add one if it does not exist.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ * @created: whether the volume has been created or not
+ *
+ * This function returns a pointer to the new volume description or an
+ * ERR_PTR if the operation failed.
+ */
+static struct ubi_ainf_volume *ubi_find_or_add_av(struct ubi_attach_info *ai,
+						  int vol_id, bool *created)
+{
+	return find_or_add_av(ai, vol_id, AV_FIND_OR_ADD, created);
+}
+
+/**
+ * ubi_alloc_aeb - allocate an aeb element
+ * @ai: attaching information
+ * @pnum: physical eraseblock number
+ * @ec: erase counter of the physical eraseblock
+ *
+ * Allocate an aeb object and initialize the pnum and ec information.
+ * vol_id and lnum are set to UBI_UNKNOWN, and the other fields are
+ * initialized to zero.
+ * Note that the element is not added in any list or RB tree.
+ */
+struct ubi_ainf_peb *ubi_alloc_aeb(struct ubi_attach_info *ai, int pnum,
+				   int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = kmem_cache_zalloc(ai->aeb_slab_cache, GFP_KERNEL);
+	if (!aeb)
+		return NULL;
+
+	aeb->pnum = pnum;
+	aeb->ec = ec;
+	aeb->vol_id = UBI_UNKNOWN;
+	aeb->lnum = UBI_UNKNOWN;
+
+	return aeb;
+}
+
+/**
+ * ubi_free_aeb - free an aeb element
+ * @ai: attaching information
+ * @aeb: the element to free
+ *
+ * Free an aeb object. The caller must have removed the element from any list
+ * or RB tree.
+ */
+void ubi_free_aeb(struct ubi_attach_info *ai, struct ubi_ainf_peb *aeb)
+{
+	kmem_cache_free(ai->aeb_slab_cache, aeb);
+}
+
+/**
+ * add_to_list - add physical eraseblock to a list.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to add
+ * @vol_id: the last used volume id for the PEB
+ * @lnum: the last used LEB number for the PEB
+ * @ec: erase counter of the physical eraseblock
+ * @to_head: if not zero, add to the head of the list
+ * @list: the list to add to
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for physical
+ * eraseblock @pnum and adds it to the "free", "erase", or "alien" lists.
+ * It stores the @lnum and @vol_id alongside, which can both be
+ * %UBI_UNKNOWN if they are not available, not readable, or not assigned.
+ * If @to_head is not zero, PEB will be added to the head of the list, which
+ * basically means it will be processed first later. E.g., we add corrupted
+ * PEBs (corrupted due to power cuts) to the head of the erase list to make
+ * sure we erase them first and get rid of corruptions ASAP. This function
+ * returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int add_to_list(struct ubi_attach_info *ai, int pnum, int vol_id,
+		       int lnum, int ec, int to_head, struct list_head *list)
+{
+	struct ubi_ainf_peb *aeb;
+
+	if (list == &ai->free) {
+		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
+	} else if (list == &ai->erase) {
+		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
+	} else if (list == &ai->alien) {
+		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
+		ai->alien_peb_count += 1;
+	} else
+		BUG();
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = vol_id;
+	aeb->lnum = lnum;
+	if (to_head)
+		list_add(&aeb->u.list, list);
+	else
+		list_add_tail(&aeb->u.list, list);
+	return 0;
+}
+
+/**
+ * add_corrupted - add a corrupted physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to add
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a corrupted
+ * physical eraseblock @pnum and adds it to the 'corr' list.  The corruption
+ * was presumably not caused by a power cut. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	ai->corr_peb_count += 1;
+	list_add(&aeb->u.list, &ai->corr);
+	return 0;
+}
+
+/**
+ * add_fastmap - add a Fastmap related physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number the VID header came from
+ * @vid_hdr: the volume identifier header
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a Fastamp
+ * physical eraseblock @pnum and adds it to the 'fastmap' list.
+ * Such blocks can be Fastmap super and data blocks from both the most
+ * recent Fastmap we're attaching from or from old Fastmaps which will
+ * be erased.
+ */
+static int add_fastmap(struct ubi_attach_info *ai, int pnum,
+		       struct ubi_vid_hdr *vid_hdr, int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = be32_to_cpu(vid_hdr->vol_id);
+	aeb->sqnum = be64_to_cpu(vid_hdr->sqnum);
+	list_add(&aeb->u.list, &ai->fastmap);
+
+	dbg_bld("add to fastmap list: PEB %d, vol_id %d, sqnum: %llu", pnum,
+		aeb->vol_id, aeb->sqnum);
+
+	return 0;
+}
+
+/**
+ * validate_vid_hdr - check volume identifier header.
+ * @ubi: UBI device description object
+ * @vid_hdr: the volume identifier header to check
+ * @av: information about the volume this logical eraseblock belongs to
+ * @pnum: physical eraseblock number the VID header came from
+ *
+ * This function checks that data stored in @vid_hdr is consistent. Returns
+ * non-zero if an inconsistency was found and zero if not.
+ *
+ * Note, UBI does sanity check of everything it reads from the flash media.
+ * Most of the checks are done in the I/O sub-system. Here we check that the
+ * information in the VID header is consistent to the information in other VID
+ * headers of the same volume.
+ */
+static int validate_vid_hdr(const struct ubi_device *ubi,
+			    const struct ubi_vid_hdr *vid_hdr,
+			    const struct ubi_ainf_volume *av, int pnum)
+{
+	int vol_type = vid_hdr->vol_type;
+	int vol_id = be32_to_cpu(vid_hdr->vol_id);
+	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
+	int data_pad = be32_to_cpu(vid_hdr->data_pad);
+
+	if (av->leb_count != 0) {
+		int av_vol_type;
+
+		/*
+		 * This is not the first logical eraseblock belonging to this
+		 * volume. Ensure that the data in its VID header is consistent
+		 * to the data in previous logical eraseblock headers.
+		 */
+
+		if (vol_id != av->vol_id) {
+			ubi_err(ubi, "inconsistent vol_id");
+			goto bad;
+		}
+
+		if (av->vol_type == UBI_STATIC_VOLUME)
+			av_vol_type = UBI_VID_STATIC;
+		else
+			av_vol_type = UBI_VID_DYNAMIC;
+
+		if (vol_type != av_vol_type) {
+			ubi_err(ubi, "inconsistent vol_type");
+			goto bad;
+		}
+
+		if (used_ebs != av->used_ebs) {
+			ubi_err(ubi, "inconsistent used_ebs");
+			goto bad;
+		}
+
+		if (data_pad != av->data_pad) {
+			ubi_err(ubi, "inconsistent data_pad");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "inconsistent VID header at PEB %d", pnum);
+	ubi_dump_vid_hdr(vid_hdr);
+	ubi_dump_av(av);
+	return -EINVAL;
+}
+
+/**
+ * add_volume - add volume to the attaching information.
+ * @ai: attaching information
+ * @vol_id: ID of the volume to add
+ * @pnum: physical eraseblock number
+ * @vid_hdr: volume identifier header
+ *
+ * If the volume corresponding to the @vid_hdr logical eraseblock is already
+ * present in the attaching information, this function does nothing. Otherwise
+ * it adds corresponding volume to the attaching information. Returns a pointer
+ * to the allocated "av" object in case of success and a negative error code in
+ * case of failure.
+ */
+static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
+					  int vol_id, int pnum,
+					  const struct ubi_vid_hdr *vid_hdr)
+{
+	struct ubi_ainf_volume *av;
+	bool created;
+
+	ubi_assert(vol_id == be32_to_cpu(vid_hdr->vol_id));
+
+	av = ubi_find_or_add_av(ai, vol_id, &created);
+	if (IS_ERR(av) || !created)
+		return av;
+
+	av->used_ebs = be32_to_cpu(vid_hdr->used_ebs);
+	av->data_pad = be32_to_cpu(vid_hdr->data_pad);
+	av->compat = vid_hdr->compat;
+	av->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
+							    : UBI_STATIC_VOLUME;
+
+	return av;
+}
+
+/**
+ * ubi_compare_lebs - find out which logical eraseblock is newer.
+ * @ubi: UBI device description object
+ * @aeb: first logical eraseblock to compare
+ * @pnum: physical eraseblock number of the second logical eraseblock to
+ * compare
+ * @vid_hdr: volume identifier header of the second logical eraseblock
+ *
+ * This function compares 2 copies of a LEB and informs which one is newer. In
+ * case of success this function returns a positive value, in case of failure, a
+ * negative error code is returned. The success return codes use the following
+ * bits:
+ *     o bit 0 is cleared: the first PEB (described by @aeb) is newer than the
+ *       second PEB (described by @pnum and @vid_hdr);
+ *     o bit 0 is set: the second PEB is newer;
+ *     o bit 1 is cleared: no bit-flips were detected in the newer LEB;
+ *     o bit 1 is set: bit-flips were detected in the newer LEB;
+ *     o bit 2 is cleared: the older LEB is not corrupted;
+ *     o bit 2 is set: the older LEB is corrupted.
+ */
+int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
+			int pnum, const struct ubi_vid_hdr *vid_hdr)
+{
+	int len, err, second_is_newer, bitflips = 0, corrupted = 0;
+	uint32_t data_crc, crc;
+	struct ubi_vid_io_buf *vidb = NULL;
+	unsigned long long sqnum2 = be64_to_cpu(vid_hdr->sqnum);
+
+	if (sqnum2 == aeb->sqnum) {
+		/*
+		 * This must be a really ancient UBI image which has been
+		 * created before sequence numbers support has been added. At
+		 * that times we used 32-bit LEB versions stored in logical
+		 * eraseblocks. That was before UBI got into mainline. We do not
+		 * support these images anymore. Well, those images still work,
+		 * but only if no unclean reboots happened.
+		 */
+		ubi_err(ubi, "unsupported on-flash UBI format");
+		return -EINVAL;
+	}
+
+	/* Obviously the LEB with lower sequence counter is older */
+	second_is_newer = (sqnum2 > aeb->sqnum);
+
+	/*
+	 * Now we know which copy is newer. If the copy flag of the PEB with
+	 * newer version is not set, then we just return, otherwise we have to
+	 * check data CRC. For the second PEB we already have the VID header,
+	 * for the first one - we'll need to re-read it from flash.
+	 *
+	 * Note: this may be optimized so that we wouldn't read twice.
+	 */
+
+	if (second_is_newer) {
+		if (!vid_hdr->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("second PEB %d is newer, copy_flag is unset",
+				pnum);
+			return 1;
+		}
+	} else {
+		if (!aeb->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("first PEB %d is newer, copy_flag is unset",
+				pnum);
+			return bitflips << 1;
+		}
+
+		vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+		if (!vidb)
+			return -ENOMEM;
+
+		pnum = aeb->pnum;
+		err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
+		if (err) {
+			if (err == UBI_IO_BITFLIPS)
+				bitflips = 1;
+			else {
+				ubi_err(ubi, "VID of PEB %d header is bad, but it was OK earlier, err %d",
+					pnum, err);
+				if (err > 0)
+					err = -EIO;
+
+				goto out_free_vidh;
+			}
+		}
+
+		vid_hdr = ubi_get_vid_hdr(vidb);
+	}
+
+	/* Read the data of the copy and check the CRC */
+
+	len = be32_to_cpu(vid_hdr->data_size);
+
+	mutex_lock(&ubi->buf_mutex);
+	err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, len);
+	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
+		goto out_unlock;
+
+	data_crc = be32_to_cpu(vid_hdr->data_crc);
+	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, len);
+	if (crc != data_crc) {
+		dbg_bld("PEB %d CRC error: calculated %#08x, must be %#08x",
+			pnum, crc, data_crc);
+		corrupted = 1;
+		bitflips = 0;
+		second_is_newer = !second_is_newer;
+	} else {
+		dbg_bld("PEB %d CRC is OK", pnum);
+		bitflips |= !!err;
+	}
+	mutex_unlock(&ubi->buf_mutex);
+
+	ubi_free_vid_buf(vidb);
+
+	if (second_is_newer)
+		dbg_bld("second PEB %d is newer, copy_flag is set", pnum);
+	else
+		dbg_bld("first PEB %d is newer, copy_flag is set", pnum);
+
+	return second_is_newer | (bitflips << 1) | (corrupted << 2);
+
+out_unlock:
+	mutex_unlock(&ubi->buf_mutex);
+out_free_vidh:
+	ubi_free_vid_buf(vidb);
+	return err;
+}
+
+/**
+ * ubi_add_to_av - add used physical eraseblock to the attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: the physical eraseblock number
+ * @ec: erase counter
+ * @vid_hdr: the volume identifier header
+ * @bitflips: if bit-flips were detected when this physical eraseblock was read
+ *
+ * This function adds information about a used physical eraseblock to the
+ * 'used' tree of the corresponding volume. The function is rather complex
+ * because it has to handle cases when this is not the first physical
+ * eraseblock belonging to the same logical eraseblock, and the newer one has
+ * to be picked, while the older one has to be dropped. This function returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
+		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips)
+{
+	int err, vol_id, lnum;
+	unsigned long long sqnum;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb;
+	struct rb_node **p, *parent = NULL;
+
+	vol_id = be32_to_cpu(vid_hdr->vol_id);
+	lnum = be32_to_cpu(vid_hdr->lnum);
+	sqnum = be64_to_cpu(vid_hdr->sqnum);
+
+	dbg_bld("PEB %d, LEB %d:%d, EC %d, sqnum %llu, bitflips %d",
+		pnum, vol_id, lnum, ec, sqnum, bitflips);
+
+	av = add_volume(ai, vol_id, pnum, vid_hdr);
+	if (IS_ERR(av))
+		return PTR_ERR(av);
+
+	if (ai->max_sqnum < sqnum)
+		ai->max_sqnum = sqnum;
+
+	/*
+	 * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
+	 * if this is the first instance of this logical eraseblock or not.
+	 */
+	p = &av->root.rb_node;
+	while (*p) {
+		int cmp_res;
+
+		parent = *p;
+		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+		if (lnum != aeb->lnum) {
+			if (lnum < aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+			continue;
+		}
+
+		/*
+		 * There is already a physical eraseblock describing the same
+		 * logical eraseblock present.
+		 */
+
+		dbg_bld("this LEB already exists: PEB %d, sqnum %llu, EC %d",
+			aeb->pnum, aeb->sqnum, aeb->ec);
+
+		/*
+		 * Make sure that the logical eraseblocks have different
+		 * sequence numbers. Otherwise the image is bad.
+		 *
+		 * However, if the sequence number is zero, we assume it must
+		 * be an ancient UBI image from the era when UBI did not have
+		 * sequence numbers. We still can attach these images, unless
+		 * there is a need to distinguish between old and new
+		 * eraseblocks, in which case we'll refuse the image in
+		 * 'ubi_compare_lebs()'. In other words, we attach old clean
+		 * images, but refuse attaching old images with duplicated
+		 * logical eraseblocks because there was an unclean reboot.
+		 */
+		if (aeb->sqnum == sqnum && sqnum != 0) {
+			ubi_err(ubi, "two LEBs with same sequence number %llu",
+				sqnum);
+			ubi_dump_aeb(aeb, 0);
+			ubi_dump_vid_hdr(vid_hdr);
+			return -EINVAL;
+		}
+
+		/*
+		 * Now we have to drop the older one and preserve the newer
+		 * one.
+		 */
+		cmp_res = ubi_compare_lebs(ubi, aeb, pnum, vid_hdr);
+		if (cmp_res < 0)
+			return cmp_res;
+
+		if (cmp_res & 1) {
+			/*
+			 * This logical eraseblock is newer than the one
+			 * found earlier.
+			 */
+			err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
+			if (err)
+				return err;
+
+			err = add_to_list(ai, aeb->pnum, aeb->vol_id,
+					  aeb->lnum, aeb->ec, cmp_res & 4,
+					  &ai->erase);
+			if (err)
+				return err;
+
+			aeb->ec = ec;
+			aeb->pnum = pnum;
+			aeb->vol_id = vol_id;
+			aeb->lnum = lnum;
+			aeb->scrub = ((cmp_res & 2) || bitflips);
+			aeb->copy_flag = vid_hdr->copy_flag;
+			aeb->sqnum = sqnum;
+
+			if (av->highest_lnum == lnum)
+				av->last_data_size =
+					be32_to_cpu(vid_hdr->data_size);
+
+			return 0;
+		} else {
+			/*
+			 * This logical eraseblock is older than the one found
+			 * previously.
+			 */
+			return add_to_list(ai, pnum, vol_id, lnum, ec,
+					   cmp_res & 4, &ai->erase);
+		}
+	}
+
+	/*
+	 * We've met this logical eraseblock for the first time, add it to the
+	 * attaching information.
+	 */
+
+	err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
+	if (err)
+		return err;
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = vol_id;
+	aeb->lnum = lnum;
+	aeb->scrub = bitflips;
+	aeb->copy_flag = vid_hdr->copy_flag;
+	aeb->sqnum = sqnum;
+
+	if (av->highest_lnum <= lnum) {
+		av->highest_lnum = lnum;
+		av->last_data_size = be32_to_cpu(vid_hdr->data_size);
+	}
+
+	av->leb_count += 1;
+	rb_link_node(&aeb->u.rb, parent, p);
+	rb_insert_color(&aeb->u.rb, &av->root);
+	return 0;
+}
+
+/**
+ * ubi_add_av - add volume to the attaching information.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ *
+ * This function returns a pointer to the new volume description or an
+ * ERR_PTR if the operation failed.
+ */
+struct ubi_ainf_volume *ubi_add_av(struct ubi_attach_info *ai, int vol_id)
+{
+	bool created;
+
+	return find_or_add_av(ai, vol_id, AV_ADD, &created);
+}
+
+/**
+ * ubi_find_av - find volume in the attaching information.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ *
+ * This function returns a pointer to the volume description or %NULL if there
+ * are no data about this volume in the attaching information.
+ */
+struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
+				    int vol_id)
+{
+	bool created;
+
+	return find_or_add_av((struct ubi_attach_info *)ai, vol_id, AV_FIND,
+			      &created);
+}
+
+static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
+		       struct list_head *list);
+
+/**
+ * ubi_remove_av - delete attaching information about a volume.
+ * @ai: attaching information
+ * @av: the volume attaching information to delete
+ */
+void ubi_remove_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
+{
+	dbg_bld("remove attaching information about volume %d", av->vol_id);
+
+	rb_erase(&av->rb, &ai->volumes);
+	destroy_av(ai, av, &ai->erase);
+	ai->vols_found -= 1;
+}
+
+/**
+ * early_erase_peb - erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to erase;
+ * @ec: erase counter value to write (%UBI_UNKNOWN if it is unknown)
+ *
+ * This function erases physical eraseblock 'pnum', and writes the erase
+ * counter header to it. This function should only be used on UBI device
+ * initialization stages, when the EBA sub-system had not been yet initialized.
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int early_erase_peb(struct ubi_device *ubi,
+			   const struct ubi_attach_info *ai, int pnum, int ec)
+{
+	int err;
+	struct ubi_ec_hdr *ec_hdr;
+
+	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
+		/*
+		 * Erase counter overflow. Upgrade UBI and use 64-bit
+		 * erase counters internally.
+		 */
+		ubi_err(ubi, "erase counter overflow at PEB %d, EC %d",
+			pnum, ec);
+		return -EINVAL;
+	}
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	ec_hdr->ec = cpu_to_be64(ec);
+
+	err = ubi_io_sync_erase(ubi, pnum, 0);
+	if (err < 0)
+		goto out_free;
+
+	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
+
+out_free:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * ubi_early_get_peb - get a free physical eraseblock.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns a free physical eraseblock. It is supposed to be
+ * called on the UBI initialization stages when the wear-leveling sub-system is
+ * not initialized yet. This function picks a physical eraseblocks from one of
+ * the lists, writes the EC header if it is needed, and removes it from the
+ * list.
+ *
+ * This function returns a pointer to the "aeb" of the found free PEB in case
+ * of success and an error code in case of failure.
+ */
+struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
+				       struct ubi_attach_info *ai)
+{
+	int err = 0;
+	struct ubi_ainf_peb *aeb, *tmp_aeb;
+
+	if (!list_empty(&ai->free)) {
+		aeb = list_entry(ai->free.next, struct ubi_ainf_peb, u.list);
+		list_del(&aeb->u.list);
+		dbg_bld("return free PEB %d, EC %d", aeb->pnum, aeb->ec);
+		return aeb;
+	}
+
+	/*
+	 * We try to erase the first physical eraseblock from the erase list
+	 * and pick it if we succeed, or try to erase the next one if not. And
+	 * so forth. We don't want to take care about bad eraseblocks here -
+	 * they'll be handled later.
+	 */
+	list_for_each_entry_safe(aeb, tmp_aeb, &ai->erase, u.list) {
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+		err = early_erase_peb(ubi, ai, aeb->pnum, aeb->ec+1);
+		if (err)
+			continue;
+
+		aeb->ec += 1;
+		list_del(&aeb->u.list);
+		dbg_bld("return PEB %d, EC %d", aeb->pnum, aeb->ec);
+		return aeb;
+	}
+
+	ubi_err(ubi, "no free eraseblocks");
+	return ERR_PTR(-ENOSPC);
+}
+
+/**
+ * check_corruption - check the data area of PEB.
+ * @ubi: UBI device description object
+ * @vid_hdr: the (corrupted) VID header of this PEB
+ * @pnum: the physical eraseblock number to check
+ *
+ * This is a helper function which is used to distinguish between VID header
+ * corruptions caused by power cuts and other reasons. If the PEB contains only
+ * 0xFF bytes in the data area, the VID header is most probably corrupted
+ * because of a power cut (%0 is returned in this case). Otherwise, it was
+ * probably corrupted for some other reasons (%1 is returned in this case). A
+ * negative error code is returned if a read error occurred.
+ *
+ * If the corruption reason was a power cut, UBI can safely erase this PEB.
+ * Otherwise, it should preserve it to avoid possibly destroying important
+ * information.
+ */
+static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
+			    int pnum)
+{
+	int err;
+
+	mutex_lock(&ubi->buf_mutex);
+	memset(ubi->peb_buf, 0x00, ubi->leb_size);
+
+	err = ubi_io_read(ubi, ubi->peb_buf, pnum, ubi->leb_start,
+			  ubi->leb_size);
+	if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err)) {
+		/*
+		 * Bit-flips or integrity errors while reading the data area.
+		 * It is difficult to say for sure what type of corruption is
+		 * this, but presumably a power cut happened while this PEB was
+		 * erased, so it became unstable and corrupted, and should be
+		 * erased.
+		 */
+		err = 0;
+		goto out_unlock;
+	}
+
+	if (err)
+		goto out_unlock;
+
+	if (ubi_check_pattern(ubi->peb_buf, 0xFF, ubi->leb_size))
+		goto out_unlock;
+
+	ubi_err(ubi, "PEB %d contains corrupted VID header, and the data does not contain all 0xFF",
+		pnum);
+	ubi_err(ubi, "this may be a non-UBI PEB or a severe VID header corruption which requires manual inspection");
+	ubi_dump_vid_hdr(vid_hdr);
+	pr_err("hexdump of PEB %d offset %d, length %d",
+	       pnum, ubi->leb_start, ubi->leb_size);
+	ubi_dbg_print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+			       ubi->peb_buf, ubi->leb_size, 1);
+	err = 1;
+
+out_unlock:
+	mutex_unlock(&ubi->buf_mutex);
+	return err;
+}
+
+static bool vol_ignored(int vol_id)
+{
+	switch (vol_id) {
+		case UBI_LAYOUT_VOLUME_ID:
+		return true;
+	}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	return ubi_is_fm_vol(vol_id);
+#else
+	return false;
+#endif
+}
+
+/**
+ * scan_peb - scan and process UBI headers of a PEB.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: the physical eraseblock number
+ * @fast: true if we're scanning for a Fastmap
+ *
+ * This function reads UBI headers of PEB @pnum, checks them, and adds
+ * information about this PEB to the corresponding list or RB-tree in the
+ * "attaching info" structure. Returns zero if the physical eraseblock was
+ * successfully handled and a negative error code in case of failure.
+ */
+static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		    int pnum, bool fast)
+{
+	struct ubi_ec_hdr *ech = ai->ech;
+	struct ubi_vid_io_buf *vidb = ai->vidb;
+	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
+	long long ec;
+	int err, bitflips = 0, vol_id = -1, ec_err = 0;
+
+	dbg_bld("scan PEB %d", pnum);
+
+	/* Skip bad physical eraseblocks */
+	err = ubi_io_is_bad(ubi, pnum);
+	if (err < 0)
+		return err;
+	else if (err) {
+		ai->bad_peb_count += 1;
+		return 0;
+	}
+
+	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+	if (err < 0)
+		return err;
+	switch (err) {
+	case 0:
+		break;
+	case UBI_IO_BITFLIPS:
+		bitflips = 1;
+		break;
+	case UBI_IO_FF:
+		ai->empty_peb_count += 1;
+		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				   UBI_UNKNOWN, 0, &ai->erase);
+	case UBI_IO_FF_BITFLIPS:
+		ai->empty_peb_count += 1;
+		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				   UBI_UNKNOWN, 1, &ai->erase);
+	case UBI_IO_BAD_HDR_EBADMSG:
+	case UBI_IO_BAD_HDR:
+		/*
+		 * We have to also look at the VID header, possibly it is not
+		 * corrupted. Set %bitflips flag in order to make this PEB be
+		 * moved and EC be re-created.
+		 */
+		ec_err = err;
+		ec = UBI_UNKNOWN;
+		bitflips = 1;
+		break;
+	default:
+		ubi_err(ubi, "'ubi_io_read_ec_hdr()' returned unknown code %d",
+			err);
+		return -EINVAL;
+	}
+
+	if (!ec_err) {
+		int image_seq;
+
+		/* Make sure UBI version is OK */
+		if (ech->version != UBI_VERSION) {
+			ubi_err(ubi, "this UBI version is %d, image version is %d",
+				UBI_VERSION, (int)ech->version);
+			return -EINVAL;
+		}
+
+		ec = be64_to_cpu(ech->ec);
+		if (ec > UBI_MAX_ERASECOUNTER) {
+			/*
+			 * Erase counter overflow. The EC headers have 64 bits
+			 * reserved, but we anyway make use of only 31 bit
+			 * values, as this seems to be enough for any existing
+			 * flash. Upgrade UBI and use 64-bit erase counters
+			 * internally.
+			 */
+			ubi_err(ubi, "erase counter overflow, max is %d",
+				UBI_MAX_ERASECOUNTER);
+			ubi_dump_ec_hdr(ech);
+			return -EINVAL;
+		}
+
+		/*
+		 * Make sure that all PEBs have the same image sequence number.
+		 * This allows us to detect situations when users flash UBI
+		 * images incorrectly, so that the flash has the new UBI image
+		 * and leftovers from the old one. This feature was added
+		 * relatively recently, and the sequence number was always
+		 * zero, because old UBI implementations always set it to zero.
+		 * For this reasons, we do not panic if some PEBs have zero
+		 * sequence number, while other PEBs have non-zero sequence
+		 * number.
+		 */
+		image_seq = be32_to_cpu(ech->image_seq);
+		if (!ubi->image_seq)
+			ubi->image_seq = image_seq;
+		if (image_seq && ubi->image_seq != image_seq) {
+			ubi_err(ubi, "bad image sequence number %d in PEB %d, expected %d",
+				image_seq, pnum, ubi->image_seq);
+			ubi_dump_ec_hdr(ech);
+			return -EINVAL;
+		}
+	}
+
+	/* OK, we've done with the EC header, let's look at the VID header */
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
+	if (err < 0)
+		return err;
+	switch (err) {
+	case 0:
+		break;
+	case UBI_IO_BITFLIPS:
+		bitflips = 1;
+		break;
+	case UBI_IO_BAD_HDR_EBADMSG:
+		if (ec_err == UBI_IO_BAD_HDR_EBADMSG)
+			/*
+			 * Both EC and VID headers are corrupted and were read
+			 * with data integrity error, probably this is a bad
+			 * PEB, bit it is not marked as bad yet. This may also
+			 * be a result of power cut during erasure.
+			 */
+			ai->maybe_bad_peb_count += 1;
+		fallthrough;
+	case UBI_IO_BAD_HDR:
+			/*
+			 * If we're facing a bad VID header we have to drop *all*
+			 * Fastmap data structures we find. The most recent Fastmap
+			 * could be bad and therefore there is a chance that we attach
+			 * from an old one. On a fine MTD stack a PEB must not render
+			 * bad all of a sudden, but the reality is different.
+			 * So, let's be paranoid and help finding the root cause by
+			 * falling back to scanning mode instead of attaching with a
+			 * bad EBA table and cause data corruption which is hard to
+			 * analyze.
+			 */
+			if (fast)
+				ai->force_full_scan = 1;
+
+		if (ec_err)
+			/*
+			 * Both headers are corrupted. There is a possibility
+			 * that this a valid UBI PEB which has corresponding
+			 * LEB, but the headers are corrupted. However, it is
+			 * impossible to distinguish it from a PEB which just
+			 * contains garbage because of a power cut during erase
+			 * operation. So we just schedule this PEB for erasure.
+			 *
+			 * Besides, in case of NOR flash, we deliberately
+			 * corrupt both headers because NOR flash erasure is
+			 * slow and can start from the end.
+			 */
+			err = 0;
+		else
+			/*
+			 * The EC was OK, but the VID header is corrupted. We
+			 * have to check what is in the data area.
+			 */
+			err = check_corruption(ubi, vidh, pnum);
+
+		if (err < 0)
+			return err;
+		else if (!err)
+			/* This corruption is caused by a power cut */
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 1, &ai->erase);
+		else
+			/* This is an unexpected corruption */
+			err = add_corrupted(ai, pnum, ec);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	case UBI_IO_FF_BITFLIPS:
+		err = add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				  ec, 1, &ai->erase);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	case UBI_IO_FF:
+		if (ec_err || bitflips)
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 1, &ai->erase);
+		else
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 0, &ai->free);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	default:
+		ubi_err(ubi, "'ubi_io_read_vid_hdr()' returned unknown code %d",
+			err);
+		return -EINVAL;
+	}
+
+	vol_id = be32_to_cpu(vidh->vol_id);
+	if (vol_id > UBI_MAX_VOLUMES && !vol_ignored(vol_id)) {
+		int lnum = be32_to_cpu(vidh->lnum);
+
+		/* Unsupported internal volume */
+		switch (vidh->compat) {
+		case UBI_COMPAT_DELETE:
+			ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
+				vol_id, lnum);
+
+			err = add_to_list(ai, pnum, vol_id, lnum,
+					  ec, 1, &ai->erase);
+			if (err)
+				return err;
+			return 0;
+
+		case UBI_COMPAT_RO:
+			ubi_msg(ubi, "read-only compatible internal volume %d:%d found, switch to read-only mode",
+				vol_id, lnum);
+			ubi->ro_mode = 1;
+			break;
+
+		case UBI_COMPAT_PRESERVE:
+			ubi_msg(ubi, "\"preserve\" compatible internal volume %d:%d found",
+				vol_id, lnum);
+			err = add_to_list(ai, pnum, vol_id, lnum,
+					  ec, 0, &ai->alien);
+			if (err)
+				return err;
+			return 0;
+
+		case UBI_COMPAT_REJECT:
+			ubi_err(ubi, "incompatible internal volume %d:%d found",
+				vol_id, lnum);
+			return -EINVAL;
+		}
+	}
+
+	if (ec_err)
+		ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
+			 pnum);
+
+	if (ubi_is_fm_vol(vol_id))
+		err = add_fastmap(ai, pnum, vidh, ec);
+	else
+		err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
+	if (err)
+		return err;
+
+adjust_mean_ec:
+	if (!ec_err) {
+		ai->ec_sum += ec;
+		ai->ec_count += 1;
+		if (ec > ai->max_ec)
+			ai->max_ec = ec;
+		if (ec < ai->min_ec)
+			ai->min_ec = ec;
+	}
+
+	return 0;
+}
+
+/**
+ * late_analysis - analyze the overall situation with PEB.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This is a helper function which takes a look what PEBs we have after we
+ * gather information about all of them ("ai" is compete). It decides whether
+ * the flash is empty and should be formatted of whether there are too many
+ * corrupted PEBs and we should not attach this MTD device. Returns zero if we
+ * should proceed with attaching the MTD device, and %-EINVAL if we should not.
+ */
+static int late_analysis(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb;
+	int max_corr, peb_count;
+
+	peb_count = ubi->peb_count - ai->bad_peb_count - ai->alien_peb_count;
+	max_corr = peb_count / 20 ?: 8;
+
+	/*
+	 * Few corrupted PEBs is not a problem and may be just a result of
+	 * unclean reboots. However, many of them may indicate some problems
+	 * with the flash HW or driver.
+	 */
+	if (ai->corr_peb_count) {
+		ubi_err(ubi, "%d PEBs are corrupted and preserved",
+			ai->corr_peb_count);
+		pr_err("Corrupted PEBs are:");
+		list_for_each_entry(aeb, &ai->corr, u.list)
+			pr_cont(" %d", aeb->pnum);
+		pr_cont("\n");
+
+		/*
+		 * If too many PEBs are corrupted, we refuse attaching,
+		 * otherwise, only print a warning.
+		 */
+		if (ai->corr_peb_count >= max_corr) {
+			ubi_err(ubi, "too many corrupted PEBs, refusing");
+			return -EINVAL;
+		}
+	}
+
+	if (ai->empty_peb_count + ai->maybe_bad_peb_count == peb_count) {
+		/*
+		 * All PEBs are empty, or almost all - a couple PEBs look like
+		 * they may be bad PEBs which were not marked as bad yet.
+		 *
+		 * This piece of code basically tries to distinguish between
+		 * the following situations:
+		 *
+		 * 1. Flash is empty, but there are few bad PEBs, which are not
+		 *    marked as bad so far, and which were read with error. We
+		 *    want to go ahead and format this flash. While formatting,
+		 *    the faulty PEBs will probably be marked as bad.
+		 *
+		 * 2. Flash contains non-UBI data and we do not want to format
+		 *    it and destroy possibly important information.
+		 */
+		if (ai->maybe_bad_peb_count <= 2) {
+			ai->is_empty = 1;
+			ubi_msg(ubi, "empty MTD device detected");
+			get_random_bytes(&ubi->image_seq,
+					 sizeof(ubi->image_seq));
+		} else {
+			ubi_err(ubi, "MTD device is not UBI-formatted and possibly contains non-UBI data - refusing it");
+			return -EINVAL;
+		}
+
+	}
+
+	return 0;
+}
+
+/**
+ * destroy_av - free volume attaching information.
+ * @av: volume attaching information
+ * @ai: attaching information
+ * @list: put the aeb elements in there if !NULL, otherwise free them
+ *
+ * This function destroys the volume attaching information.
+ */
+static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
+		       struct list_head *list)
+{
+	struct ubi_ainf_peb *aeb;
+	struct rb_node *this = av->root.rb_node;
+
+	while (this) {
+		if (this->rb_left)
+			this = this->rb_left;
+		else if (this->rb_right)
+			this = this->rb_right;
+		else {
+			aeb = rb_entry(this, struct ubi_ainf_peb, u.rb);
+			this = rb_parent(this);
+			if (this) {
+				if (this->rb_left == &aeb->u.rb)
+					this->rb_left = NULL;
+				else
+					this->rb_right = NULL;
+			}
+
+			if (list)
+				list_add_tail(&aeb->u.list, list);
+			else
+				ubi_free_aeb(ai, aeb);
+		}
+	}
+	kfree(av);
+}
+
+/**
+ * destroy_ai - destroy attaching information.
+ * @ai: attaching information
+ */
+static void destroy_ai(struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb, *aeb_tmp;
+	struct ubi_ainf_volume *av;
+	struct rb_node *rb;
+
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->alien, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->erase, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->corr, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->free, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->fastmap, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+
+	/* Destroy the volume RB-tree */
+	rb = ai->volumes.rb_node;
+	while (rb) {
+		if (rb->rb_left)
+			rb = rb->rb_left;
+		else if (rb->rb_right)
+			rb = rb->rb_right;
+		else {
+			av = rb_entry(rb, struct ubi_ainf_volume, rb);
+
+			rb = rb_parent(rb);
+			if (rb) {
+				if (rb->rb_left == &av->rb)
+					rb->rb_left = NULL;
+				else
+					rb->rb_right = NULL;
+			}
+
+			destroy_av(ai, av, NULL);
+		}
+	}
+
+	kmem_cache_destroy(ai->aeb_slab_cache);
+	kfree(ai);
+}
+
+/**
+ * scan_all - scan entire MTD device.
+ * @ubi: UBI device description object
+ * @ai: attach info object
+ * @start: start scanning at this PEB
+ *
+ * This function does full scanning of an MTD device and returns complete
+ * information about it in form of a "struct ubi_attach_info" object. In case
+ * of failure, an error code is returned.
+ */
+static int scan_all(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		    int start)
+{
+	int err, pnum;
+	struct rb_node *rb1, *rb2;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb;
+
+	err = -ENOMEM;
+
+	ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ai->ech)
+		return err;
+
+	ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!ai->vidb)
+		goto out_ech;
+
+	for (pnum = start; pnum < ubi->peb_count; pnum++) {
+		cond_resched();
+
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, ai, pnum, false);
+		if (err < 0)
+			goto out_vidh;
+	}
+
+	ubi_msg(ubi, "scanning is finished");
+
+	/* Calculate mean erase counter */
+	if (ai->ec_count)
+		ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
+
+	err = late_analysis(ubi, ai);
+	if (err)
+		goto out_vidh;
+
+	/*
+	 * In case of unknown erase counter we use the mean erase counter
+	 * value.
+	 */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			if (aeb->ec == UBI_UNKNOWN)
+				aeb->ec = ai->mean_ec;
+	}
+
+	list_for_each_entry(aeb, &ai->free, u.list) {
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+	}
+
+	list_for_each_entry(aeb, &ai->corr, u.list)
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+	err = self_check_ai(ubi, ai);
+	if (err)
+		goto out_vidh;
+
+	ubi_free_vid_buf(ai->vidb);
+	kfree(ai->ech);
+
+	return 0;
+
+out_vidh:
+	ubi_free_vid_buf(ai->vidb);
+out_ech:
+	kfree(ai->ech);
+	return err;
+}
+
+static struct ubi_attach_info *alloc_ai(void)
+{
+	struct ubi_attach_info *ai;
+
+	ai = kzalloc(sizeof(struct ubi_attach_info), GFP_KERNEL);
+	if (!ai)
+		return ai;
+
+	INIT_LIST_HEAD(&ai->corr);
+	INIT_LIST_HEAD(&ai->free);
+	INIT_LIST_HEAD(&ai->erase);
+	INIT_LIST_HEAD(&ai->alien);
+	INIT_LIST_HEAD(&ai->fastmap);
+	ai->volumes = RB_ROOT;
+	ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
+					       sizeof(struct ubi_ainf_peb),
+					       0, 0, NULL);
+	if (!ai->aeb_slab_cache) {
+		kfree(ai);
+		ai = NULL;
+	}
+
+	return ai;
+}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+
+/**
+ * scan_fast - try to find a fastmap and attach from it.
+ * @ubi: UBI device description object
+ * @ai: attach info object
+ *
+ * Returns 0 on success, negative return values indicate an internal
+ * error.
+ * UBI_NO_FASTMAP denotes that no fastmap was found.
+ * UBI_BAD_FASTMAP denotes that the found fastmap was invalid.
+ */
+static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
+{
+	int err, pnum;
+	struct ubi_attach_info *scan_ai;
+
+	err = -ENOMEM;
+
+	scan_ai = alloc_ai();
+	if (!scan_ai)
+		goto out;
+
+	scan_ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!scan_ai->ech)
+		goto out_ai;
+
+	scan_ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!scan_ai->vidb)
+		goto out_ech;
+
+	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
+		cond_resched();
+
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, scan_ai, pnum, true);
+		if (err < 0)
+			goto out_vidh;
+	}
+
+	ubi_free_vid_buf(scan_ai->vidb);
+	kfree(scan_ai->ech);
+
+	if (scan_ai->force_full_scan)
+		err = UBI_NO_FASTMAP;
+	else
+		err = ubi_scan_fastmap(ubi, *ai, scan_ai);
+
+	if (err) {
+		/*
+		 * Didn't attach via fastmap, do a full scan but reuse what
+		 * we've aready scanned.
+		 */
+		destroy_ai(*ai);
+		*ai = scan_ai;
+	} else
+		destroy_ai(scan_ai);
+
+	return err;
+
+out_vidh:
+	ubi_free_vid_buf(scan_ai->vidb);
+out_ech:
+	kfree(scan_ai->ech);
+out_ai:
+	destroy_ai(scan_ai);
+out:
+	return err;
+}
+
+#endif
+
+/**
+ * ubi_attach - attach an MTD device.
+ * @ubi: UBI device descriptor
+ * @force_scan: if set to non-zero attach by scanning
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_attach(struct ubi_device *ubi, int force_scan)
+{
+	int err;
+	struct ubi_attach_info *ai;
+
+	ai = alloc_ai();
+	if (!ai)
+		return -ENOMEM;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	/* On small flash devices we disable fastmap in any case. */
+	if ((int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd) <= UBI_FM_MAX_START) {
+		ubi->fm_disabled = 1;
+		force_scan = 1;
+	}
+
+	if (force_scan)
+		err = scan_all(ubi, ai, 0);
+	else {
+		err = scan_fast(ubi, &ai);
+		if (err > 0 || mtd_is_eccerr(err)) {
+			if (err != UBI_NO_FASTMAP) {
+				destroy_ai(ai);
+				ai = alloc_ai();
+				if (!ai)
+					return -ENOMEM;
+
+				err = scan_all(ubi, ai, 0);
+			} else {
+				err = scan_all(ubi, ai, UBI_FM_MAX_START);
+			}
+		}
+	}
+#else
+	err = scan_all(ubi, ai, 0);
+#endif
+	if (err)
+		goto out_ai;
+
+	ubi->bad_peb_count = ai->bad_peb_count;
+	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
+	ubi->corr_peb_count = ai->corr_peb_count;
+	ubi->max_ec = ai->max_ec;
+	ubi->mean_ec = ai->mean_ec;
+	dbg_gen("max. sequence number:       %llu", ai->max_sqnum);
+
+	err = ubi_read_volume_table(ubi, ai);
+	if (err)
+		goto out_ai;
+
+	err = ubi_wl_init(ubi, ai);
+	if (err)
+		goto out_vtbl;
+
+	err = ubi_eba_init(ubi, ai);
+	if (err)
+		goto out_wl;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	if (ubi->fm && ubi_dbg_chk_fastmap(ubi)) {
+		struct ubi_attach_info *scan_ai;
+
+		scan_ai = alloc_ai();
+		if (!scan_ai) {
+			err = -ENOMEM;
+			goto out_wl;
+		}
+
+		err = scan_all(ubi, scan_ai, 0);
+		if (err) {
+			destroy_ai(scan_ai);
+			goto out_wl;
+		}
+
+		err = self_check_eba(ubi, ai, scan_ai);
+		destroy_ai(scan_ai);
+
+		if (err)
+			goto out_wl;
+	}
+#endif
+
+	destroy_ai(ai);
+	return 0;
+
+out_wl:
+	ubi_wl_close(ubi);
+out_vtbl:
+	ubi_free_all_volumes(ubi);
+	vfree(ubi->vtbl);
+out_ai:
+	destroy_ai(ai);
+	return err;
+}
+
+/**
+ * self_check_ai - check the attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns zero if the attaching information is all right, and a
+ * negative error code if not or if an error occurred.
+ */
+static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	struct ubi_vid_io_buf *vidb = ai->vidb;
+	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
+	int pnum, err, vols_found = 0;
+	struct rb_node *rb1, *rb2;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *last_aeb;
+	uint8_t *buf;
+
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	/*
+	 * At first, check that attaching information is OK.
+	 */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		int leb_count = 0;
+
+		cond_resched();
+
+		vols_found += 1;
+
+		if (ai->is_empty) {
+			ubi_err(ubi, "bad is_empty flag");
+			goto bad_av;
+		}
+
+		if (av->vol_id < 0 || av->highest_lnum < 0 ||
+		    av->leb_count < 0 || av->vol_type < 0 || av->used_ebs < 0 ||
+		    av->data_pad < 0 || av->last_data_size < 0) {
+			ubi_err(ubi, "negative values");
+			goto bad_av;
+		}
+
+		if (av->vol_id >= UBI_MAX_VOLUMES &&
+		    av->vol_id < UBI_INTERNAL_VOL_START) {
+			ubi_err(ubi, "bad vol_id");
+			goto bad_av;
+		}
+
+		if (av->vol_id > ai->highest_vol_id) {
+			ubi_err(ubi, "highest_vol_id is %d, but vol_id %d is there",
+				ai->highest_vol_id, av->vol_id);
+			goto out;
+		}
+
+		if (av->vol_type != UBI_DYNAMIC_VOLUME &&
+		    av->vol_type != UBI_STATIC_VOLUME) {
+			ubi_err(ubi, "bad vol_type");
+			goto bad_av;
+		}
+
+		if (av->data_pad > ubi->leb_size / 2) {
+			ubi_err(ubi, "bad data_pad");
+			goto bad_av;
+		}
+
+		last_aeb = NULL;
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			cond_resched();
+
+			last_aeb = aeb;
+			leb_count += 1;
+
+			if (aeb->pnum < 0 || aeb->ec < 0) {
+				ubi_err(ubi, "negative values");
+				goto bad_aeb;
+			}
+
+			if (aeb->ec < ai->min_ec) {
+				ubi_err(ubi, "bad ai->min_ec (%d), %d found",
+					ai->min_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->ec > ai->max_ec) {
+				ubi_err(ubi, "bad ai->max_ec (%d), %d found",
+					ai->max_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->pnum >= ubi->peb_count) {
+				ubi_err(ubi, "too high PEB number %d, total PEBs %d",
+					aeb->pnum, ubi->peb_count);
+				goto bad_aeb;
+			}
+
+			if (av->vol_type == UBI_STATIC_VOLUME) {
+				if (aeb->lnum >= av->used_ebs) {
+					ubi_err(ubi, "bad lnum or used_ebs");
+					goto bad_aeb;
+				}
+			} else {
+				if (av->used_ebs != 0) {
+					ubi_err(ubi, "non-zero used_ebs");
+					goto bad_aeb;
+				}
+			}
+
+			if (aeb->lnum > av->highest_lnum) {
+				ubi_err(ubi, "incorrect highest_lnum or lnum");
+				goto bad_aeb;
+			}
+		}
+
+		if (av->leb_count != leb_count) {
+			ubi_err(ubi, "bad leb_count, %d objects in the tree",
+				leb_count);
+			goto bad_av;
+		}
+
+		if (!last_aeb)
+			continue;
+
+		aeb = last_aeb;
+
+		if (aeb->lnum != av->highest_lnum) {
+			ubi_err(ubi, "bad highest_lnum");
+			goto bad_aeb;
+		}
+	}
+
+	if (vols_found != ai->vols_found) {
+		ubi_err(ubi, "bad ai->vols_found %d, should be %d",
+			ai->vols_found, vols_found);
+		goto out;
+	}
+
+	/* Check that attaching information is correct */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		last_aeb = NULL;
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			int vol_type;
+
+			cond_resched();
+
+			last_aeb = aeb;
+
+			err = ubi_io_read_vid_hdr(ubi, aeb->pnum, vidb, 1);
+			if (err && err != UBI_IO_BITFLIPS) {
+				ubi_err(ubi, "VID header is not OK (%d)",
+					err);
+				if (err > 0)
+					err = -EIO;
+				return err;
+			}
+
+			vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
+				   UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
+			if (av->vol_type != vol_type) {
+				ubi_err(ubi, "bad vol_type");
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->sqnum != be64_to_cpu(vidh->sqnum)) {
+				ubi_err(ubi, "bad sqnum %llu", aeb->sqnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->vol_id != be32_to_cpu(vidh->vol_id)) {
+				ubi_err(ubi, "bad vol_id %d", av->vol_id);
+				goto bad_vid_hdr;
+			}
+
+			if (av->compat != vidh->compat) {
+				ubi_err(ubi, "bad compat %d", vidh->compat);
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->lnum != be32_to_cpu(vidh->lnum)) {
+				ubi_err(ubi, "bad lnum %d", aeb->lnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->used_ebs != be32_to_cpu(vidh->used_ebs)) {
+				ubi_err(ubi, "bad used_ebs %d", av->used_ebs);
+				goto bad_vid_hdr;
+			}
+
+			if (av->data_pad != be32_to_cpu(vidh->data_pad)) {
+				ubi_err(ubi, "bad data_pad %d", av->data_pad);
+				goto bad_vid_hdr;
+			}
+		}
+
+		if (!last_aeb)
+			continue;
+
+		if (av->highest_lnum != be32_to_cpu(vidh->lnum)) {
+			ubi_err(ubi, "bad highest_lnum %d", av->highest_lnum);
+			goto bad_vid_hdr;
+		}
+
+		if (av->last_data_size != be32_to_cpu(vidh->data_size)) {
+			ubi_err(ubi, "bad last_data_size %d",
+				av->last_data_size);
+			goto bad_vid_hdr;
+		}
+	}
+
+	/*
+	 * Make sure that all the physical eraseblocks are in one of the lists
+	 * or trees.
+	 */
+	buf = kzalloc(ubi->peb_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
+		err = ubi_io_is_bad(ubi, pnum);
+		if (err < 0) {
+			kfree(buf);
+			return err;
+		} else if (err)
+			buf[pnum] = 1;
+	}
+
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->free, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->corr, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->alien, u.list)
+		buf[aeb->pnum] = 1;
+
+	err = 0;
+	for (pnum = 0; pnum < ubi->peb_count; pnum++)
+		if (!buf[pnum]) {
+			ubi_err(ubi, "PEB %d is not referred", pnum);
+			err = 1;
+		}
+
+	kfree(buf);
+	if (err)
+		goto out;
+	return 0;
+
+bad_aeb:
+	ubi_err(ubi, "bad attaching information about LEB %d", aeb->lnum);
+	ubi_dump_aeb(aeb, 0);
+	ubi_dump_av(av);
+	goto out;
+
+bad_av:
+	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	goto out;
+
+bad_vid_hdr:
+	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	ubi_dump_vid_hdr(vidh);
+
+out:
+	dump_stack();
+	return -EINVAL;
+}