UBI: reimport UBI from Linux v3.10

This is a fresh UBI import from Linux v3.10

This is done mainly to get fastmap support.

This was tested with the i.MX nand driver, the MXS nand driver and
on CFI NOR flash.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 1728 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
new file mode 100644
index 0000000000..62d611310c
--- /dev/null
+++ b/drivers/mtd/ubi/attach.c
@@ -0,0 +1,1728 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * 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/math64.h>
+#include <stdlib.h>
+#include "ubi.h"
+
+static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai);
+
+/* Temporary variables used during scanning */
+static struct ubi_ec_hdr *ech;
+static struct ubi_vid_hdr *vidh;
+
+/**
+ * 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 = kzalloc(sizeof(*aeb), GFP_KERNEL);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->pnum = pnum;
+	aeb->vol_id = vol_id;
+	aeb->lnum = lnum;
+	aeb->ec = ec;
+	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 = kzalloc(sizeof(aeb), GFP_KERNEL);
+	if (!aeb)
+		return -ENOMEM;
+
+	ai->corr_peb_count += 1;
+	aeb->pnum = pnum;
+	aeb->ec = ec;
+	list_add(&aeb->u.list, &ai->corr);
+	return 0;
+}
+
+/**
+ * validate_vid_hdr - check volume identifier header.
+ * @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_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("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("inconsistent vol_type");
+			goto bad;
+		}
+
+		if (used_ebs != av->used_ebs) {
+			ubi_err("inconsistent used_ebs");
+			goto bad;
+		}
+
+		if (data_pad != av->data_pad) {
+			ubi_err("inconsistent data_pad");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err("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;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+
+	ubi_assert(vol_id == be32_to_cpu(vid_hdr->vol_id));
+
+	/* 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)
+			return av;
+
+		if (vol_id > av->vol_id)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	/* The volume is absent - add it */
+	av = kmalloc(sizeof(struct ubi_ainf_volume), GFP_KERNEL);
+	if (!av)
+		return ERR_PTR(-ENOMEM);
+
+	av->highest_lnum = av->leb_count = 0;
+	av->vol_id = vol_id;
+	av->root = RB_ROOT;
+	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;
+	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;
+	dbg_bld("added volume %d", vol_id);
+	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_hdr *vh = 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("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;
+		}
+
+		vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+		if (!vh)
+			return -ENOMEM;
+
+		pnum = aeb->pnum;
+		err = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
+		if (err) {
+			if (err == UBI_IO_BITFLIPS)
+				bitflips = 1;
+			else {
+				ubi_err("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 = vh;
+	}
+
+	/* Read the data of the copy and check the CRC */
+
+	len = be32_to_cpu(vid_hdr->data_size);
+
+	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;
+	}
+
+	ubi_free_vid_hdr(ubi, vh);
+
+	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:
+out_free_vidh:
+	ubi_free_vid_hdr(ubi, vh);
+	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("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(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(vid_hdr, av, pnum);
+	if (err)
+		return err;
+
+	aeb = kzalloc(sizeof(*aeb), GFP_KERNEL);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->ec = ec;
+	aeb->pnum = pnum;
+	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_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)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node *p = ai->volumes.rb_node;
+
+	while (p) {
+		av = rb_entry(p, struct ubi_ainf_volume, rb);
+
+		if (vol_id == av->vol_id)
+			return av;
+
+		if (vol_id > av->vol_id)
+			p = p->rb_left;
+		else
+			p = p->rb_right;
+	}
+
+	return NULL;
+}
+
+/**
+ * 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)
+{
+	struct rb_node *rb;
+	struct ubi_ainf_peb *aeb;
+
+	dbg_bld("remove attaching information about volume %d", av->vol_id);
+
+	while ((rb = rb_first(&av->root))) {
+		aeb = rb_entry(rb, struct ubi_ainf_peb, u.rb);
+		rb_erase(&aeb->u.rb, &av->root);
+		list_add_tail(&aeb->u.list, &ai->erase);
+	}
+
+	rb_erase(&av->rb, &ai->volumes);
+	kfree(av);
+	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("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("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;
+
+	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("PEB %d contains corrupted VID header, and the data does not contain all 0xFF",
+		pnum);
+	ubi_err("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:
+	return err;
+}
+
+/**
+ * scan_peb - scan and process UBI headers of a PEB.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: the physical eraseblock number
+ * @vid: The volume ID of the found volume will be stored in this pointer
+ * @sqnum: The sqnum of the found volume will be stored in this pointer
+ *
+ * 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, int *vid, unsigned long long *sqnum)
+{
+	long long uninitialized_var(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_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("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("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 && image_seq)
+			ubi->image_seq = image_seq;
+		if (ubi->image_seq && image_seq &&
+		    ubi->image_seq != image_seq) {
+			ubi_err("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, vidh, 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;
+	case UBI_IO_BAD_HDR:
+		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_io_read_vid_hdr()' returned unknown code %d",
+			err);
+		return -EINVAL;
+	}
+
+	vol_id = be32_to_cpu(vidh->vol_id);
+	if (vid)
+		*vid = vol_id;
+	if (sqnum)
+		*sqnum = be64_to_cpu(vidh->sqnum);
+	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOLUME_ID) {
+		int lnum = be32_to_cpu(vidh->lnum);
+
+		/* Unsupported internal volume */
+		switch (vidh->compat) {
+		case UBI_COMPAT_DELETE:
+			if (vol_id != UBI_FM_SB_VOLUME_ID
+			    && vol_id != UBI_FM_DATA_VOLUME_ID) {
+				ubi_msg("\"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("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("\"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("incompatible internal volume %d:%d found",
+				vol_id, lnum);
+			return -EINVAL;
+		}
+	}
+
+	if (ec_err)
+		ubi_warn("valid VID header but corrupted EC header at PEB %d",
+			 pnum);
+	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("%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_err(" %d", aeb->pnum);
+		pr_err("\n");
+
+		/*
+		 * If too many PEBs are corrupted, we refuse attaching,
+		 * otherwise, only print a warning.
+		 */
+		if (ai->corr_peb_count >= max_corr) {
+			ubi_err("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("empty MTD device detected");
+			get_random_bytes(&ubi->image_seq,
+					 sizeof(ubi->image_seq));
+		} else {
+			ubi_err("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
+ *
+ * This function destroys the volume attaching information.
+ */
+static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
+{
+	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;
+			}
+
+			kfree(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);
+		kfree(aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->erase, u.list) {
+		list_del(&aeb->u.list);
+		kfree(aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->corr, u.list) {
+		list_del(&aeb->u.list);
+		kfree(aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->free, u.list) {
+		list_del(&aeb->u.list);
+		kfree(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);
+		}
+	}
+
+	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;
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech)
+		return err;
+
+	vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vidh)
+		goto out_ech;
+
+	for (pnum = start; pnum < ubi->peb_count; pnum++) {
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, ai, pnum, NULL, NULL);
+		if (err < 0)
+			goto out_vidh;
+	}
+
+	ubi_msg("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_hdr(ubi, vidh);
+	kfree(ech);
+
+	return 0;
+
+out_vidh:
+	ubi_free_vid_hdr(ubi, vidh);
+out_ech:
+	kfree(ech);
+	return err;
+}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+
+/**
+ * scan_fastmap - 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, fm_anchor = -1;
+	unsigned long long max_sqnum = 0;
+
+	err = -ENOMEM;
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech)
+		goto out;
+
+	vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vidh)
+		goto out_ech;
+
+	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
+		int vol_id = -1;
+		unsigned long long sqnum = -1;
+
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, ai, pnum, &vol_id, &sqnum);
+		if (err < 0)
+			goto out_vidh;
+
+		if (vol_id == UBI_FM_SB_VOLUME_ID && sqnum > max_sqnum) {
+			max_sqnum = sqnum;
+			fm_anchor = pnum;
+		}
+	}
+
+	ubi_free_vid_hdr(ubi, vidh);
+	kfree(ech);
+
+	if (fm_anchor < 0)
+		return UBI_NO_FASTMAP;
+
+	return ubi_scan_fastmap(ubi, ai, fm_anchor);
+
+out_vidh:
+	ubi_free_vid_hdr(ubi, vidh);
+out_ech:
+	kfree(ech);
+out:
+	return err;
+}
+
+#endif
+
+static struct ubi_attach_info *alloc_ai(const char *slab_name)
+{
+	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);
+	ai->volumes = RB_ROOT;
+
+	return ai;
+}
+
+/**
+ * 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("ubi_aeb_slab_cache");
+	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) {
+			if (err != UBI_NO_FASTMAP) {
+				destroy_ai(ai);
+				ai = alloc_ai("ubi_aeb_slab_cache2");
+				if (!ai)
+					return -ENOMEM;
+			}
+
+			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_gen(ubi)) {
+		struct ubi_attach_info *scan_ai;
+
+		scan_ai = alloc_ai("ubi_ckh_aeb_slab_cache");
+		if (!scan_ai)
+			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_internal_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)
+{
+	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;
+
+		vols_found += 1;
+
+		if (ai->is_empty) {
+			ubi_err("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("negative values");
+			goto bad_av;
+		}
+
+		if (av->vol_id >= UBI_MAX_VOLUMES &&
+		    av->vol_id < UBI_INTERNAL_VOL_START) {
+			ubi_err("bad vol_id");
+			goto bad_av;
+		}
+
+		if (av->vol_id > ai->highest_vol_id) {
+			ubi_err("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("bad vol_type");
+			goto bad_av;
+		}
+
+		if (av->data_pad > ubi->leb_size / 2) {
+			ubi_err("bad data_pad");
+			goto bad_av;
+		}
+
+		last_aeb = NULL;
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			last_aeb = aeb;
+			leb_count += 1;
+
+			if (aeb->pnum < 0 || aeb->ec < 0) {
+				ubi_err("negative values");
+				goto bad_aeb;
+			}
+
+			if (aeb->ec < ai->min_ec) {
+				ubi_err("bad ai->min_ec (%d), %d found",
+					ai->min_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->ec > ai->max_ec) {
+				ubi_err("bad ai->max_ec (%d), %d found",
+					ai->max_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->pnum >= ubi->peb_count) {
+				ubi_err("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("bad lnum or used_ebs");
+					goto bad_aeb;
+				}
+			} else {
+				if (av->used_ebs != 0) {
+					ubi_err("non-zero used_ebs");
+					goto bad_aeb;
+				}
+			}
+
+			if (aeb->lnum > av->highest_lnum) {
+				ubi_err("incorrect highest_lnum or lnum");
+				goto bad_aeb;
+			}
+		}
+
+		if (av->leb_count != leb_count) {
+			ubi_err("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("bad highest_lnum");
+			goto bad_aeb;
+		}
+	}
+
+	if (vols_found != ai->vols_found) {
+		ubi_err("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;
+
+			last_aeb = aeb;
+
+			err = ubi_io_read_vid_hdr(ubi, aeb->pnum, vidh, 1);
+			if (err && err != UBI_IO_BITFLIPS) {
+				ubi_err("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("bad vol_type");
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->sqnum != be64_to_cpu(vidh->sqnum)) {
+				ubi_err("bad sqnum %llu", aeb->sqnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->vol_id != be32_to_cpu(vidh->vol_id)) {
+				ubi_err("bad vol_id %d", av->vol_id);
+				goto bad_vid_hdr;
+			}
+
+			if (av->compat != vidh->compat) {
+				ubi_err("bad compat %d", vidh->compat);
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->lnum != be32_to_cpu(vidh->lnum)) {
+				ubi_err("bad lnum %d", aeb->lnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->used_ebs != be32_to_cpu(vidh->used_ebs)) {
+				ubi_err("bad used_ebs %d", av->used_ebs);
+				goto bad_vid_hdr;
+			}
+
+			if (av->data_pad != be32_to_cpu(vidh->data_pad)) {
+				ubi_err("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("bad highest_lnum %d", av->highest_lnum);
+			goto bad_vid_hdr;
+		}
+
+		if (av->last_data_size != be32_to_cpu(vidh->data_size)) {
+			ubi_err("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("PEB %d is not referred", pnum);
+			err = 1;
+		}
+
+	kfree(buf);
+	if (err)
+		goto out;
+	return 0;
+
+bad_aeb:
+	ubi_err("bad attaching information about LEB %d", aeb->lnum);
+	ubi_dump_aeb(aeb, 0);
+	ubi_dump_av(av);
+	goto out;
+
+bad_av:
+	ubi_err("bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	goto out;
+
+bad_vid_hdr:
+	ubi_err("bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	ubi_dump_vid_hdr(vidh);
+
+out:
+	dump_stack();
+	return -EINVAL;
+}