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, 859 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
new file mode 100644
index 0000000000..596a19545b
--- /dev/null
+++ b/drivers/mtd/ubi/vtbl.c
@@ -0,0 +1,859 @@
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * 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)
+ */
+
+/*
+ * This file includes volume table manipulation code. The volume table is an
+ * on-flash table containing volume meta-data like name, number of reserved
+ * physical eraseblocks, type, etc. The volume table is stored in the so-called
+ * "layout volume".
+ *
+ * The layout volume is an internal volume which is organized as follows. It
+ * consists of two logical eraseblocks - LEB 0 and LEB 1. Each logical
+ * eraseblock stores one volume table copy, i.e. LEB 0 and LEB 1 duplicate each
+ * other. This redundancy guarantees robustness to unclean reboots. The volume
+ * table is basically an array of volume table records. Each record contains
+ * full information about the volume and protected by a CRC checksum.
+ *
+ * The volume table is changed, it is first changed in RAM. Then LEB 0 is
+ * erased, and the updated volume table is written back to LEB 0. Then same for
+ * LEB 1. This scheme guarantees recoverability from unclean reboots.
+ *
+ * In this UBI implementation the on-flash volume table does not contain any
+ * information about how much data static volumes contain.
+ *
+ * But it would still be beneficial to store this information in the volume
+ * table. For example, suppose we have a static volume X, and all its physical
+ * eraseblocks became bad for some reasons. Suppose we are attaching the
+ * corresponding MTD device, for some reason we find no logical eraseblocks
+ * corresponding to the volume X. According to the volume table volume X does
+ * exist. So we don't know whether it is just empty or all its physical
+ * eraseblocks went bad. So we cannot alarm the user properly.
+ *
+ * The volume table also stores so-called "update marker", which is used for
+ * volume updates. Before updating the volume, the update marker is set, and
+ * after the update operation is finished, the update marker is cleared. So if
+ * the update operation was interrupted (e.g. by an unclean reboot) - the
+ * update marker is still there and we know that the volume's contents is
+ * damaged.
+ */
+
+#include <linux/err.h>
+#include "ubi.h"
+
+static void self_vtbl_check(const struct ubi_device *ubi);
+
+/* Empty volume table record */
+static struct ubi_vtbl_record empty_vtbl_record;
+
+/**
+ * ubi_change_vtbl_record - change volume table record.
+ * @ubi: UBI device description object
+ * @idx: table index to change
+ * @vtbl_rec: new volume table record
+ *
+ * This function changes volume table record @idx. If @vtbl_rec is %NULL, empty
+ * volume table record is written. The caller does not have to calculate CRC of
+ * the record as it is done by this function. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
+			   struct ubi_vtbl_record *vtbl_rec)
+{
+	int i, err;
+	uint32_t crc;
+	struct ubi_volume *layout_vol;
+
+	ubi_assert(idx >= 0 && idx < ubi->vtbl_slots);
+	layout_vol = ubi->volumes[vol_id2idx(ubi, UBI_LAYOUT_VOLUME_ID)];
+
+	if (!vtbl_rec)
+		vtbl_rec = &empty_vtbl_record;
+	else {
+		crc = crc32(UBI_CRC32_INIT, vtbl_rec, UBI_VTBL_RECORD_SIZE_CRC);
+		vtbl_rec->crc = cpu_to_be32(crc);
+	}
+
+	memcpy(&ubi->vtbl[idx], vtbl_rec, sizeof(struct ubi_vtbl_record));
+	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
+		err = ubi_eba_unmap_leb(ubi, layout_vol, i);
+		if (err)
+			return err;
+
+		err = ubi_eba_write_leb(ubi, layout_vol, i, ubi->vtbl, 0,
+					ubi->vtbl_size);
+		if (err)
+			return err;
+	}
+
+	self_vtbl_check(ubi);
+	return 0;
+}
+
+/**
+ * ubi_vtbl_rename_volumes - rename UBI volumes in the volume table.
+ * @ubi: UBI device description object
+ * @rename_list: list of &struct ubi_rename_entry objects
+ *
+ * This function re-names multiple volumes specified in @req in the volume
+ * table. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubi_vtbl_rename_volumes(struct ubi_device *ubi,
+			    struct list_head *rename_list)
+{
+	int i, err;
+	struct ubi_rename_entry *re;
+	struct ubi_volume *layout_vol;
+
+	list_for_each_entry(re, rename_list, list) {
+		uint32_t crc;
+		struct ubi_volume *vol = re->desc->vol;
+		struct ubi_vtbl_record *vtbl_rec = &ubi->vtbl[vol->vol_id];
+
+		if (re->remove) {
+			memcpy(vtbl_rec, &empty_vtbl_record,
+			       sizeof(struct ubi_vtbl_record));
+			continue;
+		}
+
+		vtbl_rec->name_len = cpu_to_be16(re->new_name_len);
+		memcpy(vtbl_rec->name, re->new_name, re->new_name_len);
+		memset(vtbl_rec->name + re->new_name_len, 0,
+		       UBI_VOL_NAME_MAX + 1 - re->new_name_len);
+		crc = crc32(UBI_CRC32_INIT, vtbl_rec,
+			    UBI_VTBL_RECORD_SIZE_CRC);
+		vtbl_rec->crc = cpu_to_be32(crc);
+	}
+
+	layout_vol = ubi->volumes[vol_id2idx(ubi, UBI_LAYOUT_VOLUME_ID)];
+	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
+		err = ubi_eba_unmap_leb(ubi, layout_vol, i);
+		if (err)
+			return err;
+
+		err = ubi_eba_write_leb(ubi, layout_vol, i, ubi->vtbl, 0,
+					ubi->vtbl_size);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * vtbl_check - check if volume table is not corrupted and sensible.
+ * @ubi: UBI device description object
+ * @vtbl: volume table
+ *
+ * This function returns zero if @vtbl is all right, %1 if CRC is incorrect,
+ * and %-EINVAL if it contains inconsistent data.
+ */
+static int vtbl_check(const struct ubi_device *ubi,
+		      const struct ubi_vtbl_record *vtbl)
+{
+	int i, n, reserved_pebs, alignment, data_pad, vol_type, name_len;
+	int upd_marker, err;
+	uint32_t crc;
+	const char *name;
+
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
+		alignment = be32_to_cpu(vtbl[i].alignment);
+		data_pad = be32_to_cpu(vtbl[i].data_pad);
+		upd_marker = vtbl[i].upd_marker;
+		vol_type = vtbl[i].vol_type;
+		name_len = be16_to_cpu(vtbl[i].name_len);
+		name = &vtbl[i].name[0];
+
+		crc = crc32(UBI_CRC32_INIT, &vtbl[i], UBI_VTBL_RECORD_SIZE_CRC);
+		if (be32_to_cpu(vtbl[i].crc) != crc) {
+			ubi_err("bad CRC at record %u: %#08x, not %#08x",
+				 i, crc, be32_to_cpu(vtbl[i].crc));
+			ubi_dump_vtbl_record(&vtbl[i], i);
+			return 1;
+		}
+
+		if (reserved_pebs == 0) {
+			if (memcmp(&vtbl[i], &empty_vtbl_record,
+						UBI_VTBL_RECORD_SIZE)) {
+				err = 2;
+				goto bad;
+			}
+			continue;
+		}
+
+		if (reserved_pebs < 0 || alignment < 0 || data_pad < 0 ||
+		    name_len < 0) {
+			err = 3;
+			goto bad;
+		}
+
+		if (alignment > ubi->leb_size || alignment == 0) {
+			err = 4;
+			goto bad;
+		}
+
+		n = alignment & (ubi->min_io_size - 1);
+		if (alignment != 1 && n) {
+			err = 5;
+			goto bad;
+		}
+
+		n = ubi->leb_size % alignment;
+		if (data_pad != n) {
+			ubi_err("bad data_pad, has to be %d", n);
+			err = 6;
+			goto bad;
+		}
+
+		if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
+			err = 7;
+			goto bad;
+		}
+
+		if (upd_marker != 0 && upd_marker != 1) {
+			err = 8;
+			goto bad;
+		}
+
+		if (reserved_pebs > ubi->good_peb_count) {
+			ubi_err("too large reserved_pebs %d, good PEBs %d",
+				reserved_pebs, ubi->good_peb_count);
+			err = 9;
+			goto bad;
+		}
+
+		if (name_len > UBI_VOL_NAME_MAX) {
+			err = 10;
+			goto bad;
+		}
+
+		if (name[0] == '\0') {
+			err = 11;
+			goto bad;
+		}
+
+		if (name_len != strnlen(name, name_len + 1)) {
+			err = 12;
+			goto bad;
+		}
+	}
+
+	/* Checks that all names are unique */
+	for (i = 0; i < ubi->vtbl_slots - 1; i++) {
+		for (n = i + 1; n < ubi->vtbl_slots; n++) {
+			int len1 = be16_to_cpu(vtbl[i].name_len);
+			int len2 = be16_to_cpu(vtbl[n].name_len);
+
+			if (len1 > 0 && len1 == len2 &&
+			    !strncmp(vtbl[i].name, vtbl[n].name, len1)) {
+				ubi_err("volumes %d and %d have the same name \"%s\"",
+					i, n, vtbl[i].name);
+				ubi_dump_vtbl_record(&vtbl[i], i);
+				ubi_dump_vtbl_record(&vtbl[n], n);
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err("volume table check failed: record %d, error %d", i, err);
+	ubi_dump_vtbl_record(&vtbl[i], i);
+	return -EINVAL;
+}
+
+/**
+ * create_vtbl - create a copy of volume table.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @copy: number of the volume table copy
+ * @vtbl: contents of the volume table
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int create_vtbl(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		       int copy, void *vtbl)
+{
+	int err, tries = 0;
+	struct ubi_vid_hdr *vid_hdr;
+	struct ubi_ainf_peb *new_aeb;
+
+	dbg_gen("create volume table (copy #%d)", copy + 1);
+
+	vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vid_hdr)
+		return -ENOMEM;
+
+retry:
+	new_aeb = ubi_early_get_peb(ubi, ai);
+	if (IS_ERR(new_aeb)) {
+		err = PTR_ERR(new_aeb);
+		goto out_free;
+	}
+
+	vid_hdr->vol_type = UBI_LAYOUT_VOLUME_TYPE;
+	vid_hdr->vol_id = cpu_to_be32(UBI_LAYOUT_VOLUME_ID);
+	vid_hdr->compat = UBI_LAYOUT_VOLUME_COMPAT;
+	vid_hdr->data_size = vid_hdr->used_ebs =
+			     vid_hdr->data_pad = cpu_to_be32(0);
+	vid_hdr->lnum = cpu_to_be32(copy);
+	vid_hdr->sqnum = cpu_to_be64(++ai->max_sqnum);
+
+	/* The EC header is already there, write the VID header */
+	err = ubi_io_write_vid_hdr(ubi, new_aeb->pnum, vid_hdr);
+	if (err)
+		goto write_error;
+
+	/* Write the layout volume contents */
+	err = ubi_io_write_data(ubi, vtbl, new_aeb->pnum, 0, ubi->vtbl_size);
+	if (err)
+		goto write_error;
+
+	/*
+	 * And add it to the attaching information. Don't delete the old version
+	 * of this LEB as it will be deleted and freed in 'ubi_add_to_av()'.
+	 */
+	err = ubi_add_to_av(ubi, ai, new_aeb->pnum, new_aeb->ec, vid_hdr, 0);
+	kfree(new_aeb);
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return err;
+
+write_error:
+	if (err == -EIO && ++tries <= 5) {
+		/*
+		 * Probably this physical eraseblock went bad, try to pick
+		 * another one.
+		 */
+		list_add(&new_aeb->u.list, &ai->erase);
+		goto retry;
+	}
+	kfree(new_aeb);
+out_free:
+	ubi_free_vid_hdr(ubi, vid_hdr);
+	return err;
+
+}
+
+/**
+ * process_lvol - process the layout volume.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @av: layout volume attaching information
+ *
+ * This function is responsible for reading the layout volume, ensuring it is
+ * not corrupted, and recovering from corruptions if needed. Returns volume
+ * table in case of success and a negative error code in case of failure.
+ */
+static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
+					    struct ubi_attach_info *ai,
+					    struct ubi_ainf_volume *av)
+{
+	int err;
+	struct rb_node *rb;
+	struct ubi_ainf_peb *aeb;
+	struct ubi_vtbl_record *leb[UBI_LAYOUT_VOLUME_EBS] = { NULL, NULL };
+	int leb_corrupted[UBI_LAYOUT_VOLUME_EBS] = {1, 1};
+
+	/*
+	 * UBI goes through the following steps when it changes the layout
+	 * volume:
+	 * a. erase LEB 0;
+	 * b. write new data to LEB 0;
+	 * c. erase LEB 1;
+	 * d. write new data to LEB 1.
+	 *
+	 * Before the change, both LEBs contain the same data.
+	 *
+	 * Due to unclean reboots, the contents of LEB 0 may be lost, but there
+	 * should LEB 1. So it is OK if LEB 0 is corrupted while LEB 1 is not.
+	 * Similarly, LEB 1 may be lost, but there should be LEB 0. And
+	 * finally, unclean reboots may result in a situation when neither LEB
+	 * 0 nor LEB 1 are corrupted, but they are different. In this case, LEB
+	 * 0 contains more recent information.
+	 *
+	 * So the plan is to first check LEB 0. Then
+	 * a. if LEB 0 is OK, it must be containing the most recent data; then
+	 *    we compare it with LEB 1, and if they are different, we copy LEB
+	 *    0 to LEB 1;
+	 * b. if LEB 0 is corrupted, but LEB 1 has to be OK, and we copy LEB 1
+	 *    to LEB 0.
+	 */
+
+	dbg_gen("check layout volume");
+
+	/* Read both LEB 0 and LEB 1 into memory */
+	ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
+		leb[aeb->lnum] = vzalloc(ubi->vtbl_size);
+		if (!leb[aeb->lnum]) {
+			err = -ENOMEM;
+			goto out_free;
+		}
+
+		err = ubi_io_read_data(ubi, leb[aeb->lnum], aeb->pnum, 0,
+				       ubi->vtbl_size);
+		if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err))
+			/*
+			 * Scrub the PEB later. Note, -EBADMSG indicates an
+			 * uncorrectable ECC error, but we have our own CRC and
+			 * the data will be checked later. If the data is OK,
+			 * the PEB will be scrubbed (because we set
+			 * aeb->scrub). If the data is not OK, the contents of
+			 * the PEB will be recovered from the second copy, and
+			 * aeb->scrub will be cleared in
+			 * 'ubi_add_to_av()'.
+			 */
+			aeb->scrub = 1;
+		else if (err)
+			goto out_free;
+	}
+
+	err = -EINVAL;
+	if (leb[0]) {
+		leb_corrupted[0] = vtbl_check(ubi, leb[0]);
+		if (leb_corrupted[0] < 0)
+			goto out_free;
+	}
+
+	if (!leb_corrupted[0]) {
+		/* LEB 0 is OK */
+		if (leb[1])
+			leb_corrupted[1] = memcmp(leb[0], leb[1],
+						  ubi->vtbl_size);
+		if (leb_corrupted[1]) {
+			ubi_warn("volume table copy #2 is corrupted");
+			err = create_vtbl(ubi, ai, 1, leb[0]);
+			if (err)
+				goto out_free;
+			ubi_msg("volume table was restored");
+		}
+
+		/* Both LEB 1 and LEB 2 are OK and consistent */
+		vfree(leb[1]);
+		return leb[0];
+	} else {
+		/* LEB 0 is corrupted or does not exist */
+		if (leb[1]) {
+			leb_corrupted[1] = vtbl_check(ubi, leb[1]);
+			if (leb_corrupted[1] < 0)
+				goto out_free;
+		}
+		if (leb_corrupted[1]) {
+			/* Both LEB 0 and LEB 1 are corrupted */
+			ubi_err("both volume tables are corrupted");
+			goto out_free;
+		}
+
+		ubi_warn("volume table copy #1 is corrupted");
+		err = create_vtbl(ubi, ai, 0, leb[1]);
+		if (err)
+			goto out_free;
+		ubi_msg("volume table was restored");
+
+		vfree(leb[0]);
+		return leb[1];
+	}
+
+out_free:
+	vfree(leb[0]);
+	vfree(leb[1]);
+	return ERR_PTR(err);
+}
+
+/**
+ * create_empty_lvol - create empty layout volume.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns volume table contents in case of success and a
+ * negative error code in case of failure.
+ */
+static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi,
+						 struct ubi_attach_info *ai)
+{
+	int i;
+	struct ubi_vtbl_record *vtbl;
+
+	vtbl = vzalloc(ubi->vtbl_size);
+	if (!vtbl)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		memcpy(&vtbl[i], &empty_vtbl_record, UBI_VTBL_RECORD_SIZE);
+
+	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
+		int err;
+
+		err = create_vtbl(ubi, ai, i, vtbl);
+		if (err) {
+			vfree(vtbl);
+			return ERR_PTR(err);
+		}
+	}
+
+	return vtbl;
+}
+
+/**
+ * init_volumes - initialize volume information for existing volumes.
+ * @ubi: UBI device description object
+ * @ai: scanning information
+ * @vtbl: volume table
+ *
+ * This function allocates volume description objects for existing volumes.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int init_volumes(struct ubi_device *ubi,
+			const struct ubi_attach_info *ai,
+			const struct ubi_vtbl_record *vtbl)
+{
+	int i, reserved_pebs = 0;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		if (be32_to_cpu(vtbl[i].reserved_pebs) == 0)
+			continue; /* Empty record */
+
+		vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
+		if (!vol)
+			return -ENOMEM;
+
+		vol->reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
+		vol->alignment = be32_to_cpu(vtbl[i].alignment);
+		vol->data_pad = be32_to_cpu(vtbl[i].data_pad);
+		vol->upd_marker = vtbl[i].upd_marker;
+		vol->vol_type = vtbl[i].vol_type == UBI_VID_DYNAMIC ?
+					UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
+		vol->name_len = be16_to_cpu(vtbl[i].name_len);
+		vol->usable_leb_size = ubi->leb_size - vol->data_pad;
+		memcpy(vol->name, vtbl[i].name, vol->name_len);
+		vol->name[vol->name_len] = '\0';
+		vol->vol_id = i;
+
+		if (vtbl[i].flags & UBI_VTBL_AUTORESIZE_FLG) {
+			/* Auto re-size flag may be set only for one volume */
+			if (ubi->autoresize_vol_id != -1) {
+				ubi_err("more than one auto-resize volume (%d and %d)",
+					ubi->autoresize_vol_id, i);
+				kfree(vol);
+				return -EINVAL;
+			}
+
+			ubi->autoresize_vol_id = i;
+		}
+
+		ubi_assert(!ubi->volumes[i]);
+		ubi->volumes[i] = vol;
+		ubi->vol_count += 1;
+		vol->ubi = ubi;
+		reserved_pebs += vol->reserved_pebs;
+
+		/*
+		 * In case of dynamic volume UBI knows nothing about how many
+		 * data is stored there. So assume the whole volume is used.
+		 */
+		if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+			vol->used_ebs = vol->reserved_pebs;
+			vol->last_eb_bytes = vol->usable_leb_size;
+			vol->used_bytes =
+				(long long)vol->used_ebs * vol->usable_leb_size;
+			continue;
+		}
+
+		/* Static volumes only */
+		av = ubi_find_av(ai, i);
+		if (!av) {
+			/*
+			 * No eraseblocks belonging to this volume found. We
+			 * don't actually know whether this static volume is
+			 * completely corrupted or just contains no data. And
+			 * we cannot know this as long as data size is not
+			 * stored on flash. So we just assume the volume is
+			 * empty. FIXME: this should be handled.
+			 */
+			continue;
+		}
+
+		if (av->leb_count != av->used_ebs) {
+			/*
+			 * We found a static volume which misses several
+			 * eraseblocks. Treat it as corrupted.
+			 */
+			ubi_warn("static volume %d misses %d LEBs - corrupted",
+				 av->vol_id, av->used_ebs - av->leb_count);
+			vol->corrupted = 1;
+			continue;
+		}
+
+		vol->used_ebs = av->used_ebs;
+		vol->used_bytes =
+			(long long)(vol->used_ebs - 1) * vol->usable_leb_size;
+		vol->used_bytes += av->last_data_size;
+		vol->last_eb_bytes = av->last_data_size;
+	}
+
+	/* And add the layout volume */
+	vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
+	if (!vol)
+		return -ENOMEM;
+
+	vol->reserved_pebs = UBI_LAYOUT_VOLUME_EBS;
+	vol->alignment = UBI_LAYOUT_VOLUME_ALIGN;
+	vol->vol_type = UBI_DYNAMIC_VOLUME;
+	vol->name_len = sizeof(UBI_LAYOUT_VOLUME_NAME) - 1;
+	memcpy(vol->name, UBI_LAYOUT_VOLUME_NAME, vol->name_len + 1);
+	vol->usable_leb_size = ubi->leb_size;
+	vol->used_ebs = vol->reserved_pebs;
+	vol->last_eb_bytes = vol->reserved_pebs;
+	vol->used_bytes =
+		(long long)vol->used_ebs * (ubi->leb_size - vol->data_pad);
+	vol->vol_id = UBI_LAYOUT_VOLUME_ID;
+	vol->ref_count = 1;
+
+	ubi_assert(!ubi->volumes[i]);
+	ubi->volumes[vol_id2idx(ubi, vol->vol_id)] = vol;
+	reserved_pebs += vol->reserved_pebs;
+	ubi->vol_count += 1;
+	vol->ubi = ubi;
+
+	if (reserved_pebs > ubi->avail_pebs) {
+		ubi_err("not enough PEBs, required %d, available %d",
+			reserved_pebs, ubi->avail_pebs);
+		if (ubi->corr_peb_count)
+			ubi_err("%d PEBs are corrupted and not used",
+				ubi->corr_peb_count);
+	}
+	ubi->rsvd_pebs += reserved_pebs;
+	ubi->avail_pebs -= reserved_pebs;
+
+	return 0;
+}
+
+/**
+ * check_av - check volume attaching information.
+ * @vol: UBI volume description object
+ * @av: volume attaching information
+ *
+ * This function returns zero if the volume attaching information is consistent
+ * to the data read from the volume tabla, and %-EINVAL if not.
+ */
+static int check_av(const struct ubi_volume *vol,
+		    const struct ubi_ainf_volume *av)
+{
+	int err;
+
+	if (av->highest_lnum >= vol->reserved_pebs) {
+		err = 1;
+		goto bad;
+	}
+	if (av->leb_count > vol->reserved_pebs) {
+		err = 2;
+		goto bad;
+	}
+	if (av->vol_type != vol->vol_type) {
+		err = 3;
+		goto bad;
+	}
+	if (av->used_ebs > vol->reserved_pebs) {
+		err = 4;
+		goto bad;
+	}
+	if (av->data_pad != vol->data_pad) {
+		err = 5;
+		goto bad;
+	}
+	return 0;
+
+bad:
+	ubi_err("bad attaching information, error %d", err);
+	ubi_dump_av(av);
+	ubi_dump_vol_info(vol);
+	return -EINVAL;
+}
+
+/**
+ * check_attaching_info - check that attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * Even though we protect on-flash data by CRC checksums, we still don't trust
+ * the media. This function ensures that attaching information is consistent to
+ * the information read from the volume table. Returns zero if the attaching
+ * information is OK and %-EINVAL if it is not.
+ */
+static int check_attaching_info(const struct ubi_device *ubi,
+			       struct ubi_attach_info *ai)
+{
+	int err, i;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+
+	if (ai->vols_found > UBI_INT_VOL_COUNT + ubi->vtbl_slots) {
+		ubi_err("found %d volumes while attaching, maximum is %d + %d",
+			ai->vols_found, UBI_INT_VOL_COUNT, ubi->vtbl_slots);
+		return -EINVAL;
+	}
+
+	if (ai->highest_vol_id >= ubi->vtbl_slots + UBI_INT_VOL_COUNT &&
+	    ai->highest_vol_id < UBI_INTERNAL_VOL_START) {
+		ubi_err("too large volume ID %d found", ai->highest_vol_id);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
+		av = ubi_find_av(ai, i);
+		vol = ubi->volumes[i];
+		if (!vol) {
+			if (av)
+				ubi_remove_av(ai, av);
+			continue;
+		}
+
+		if (vol->reserved_pebs == 0) {
+			ubi_assert(i < ubi->vtbl_slots);
+
+			if (!av)
+				continue;
+
+			/*
+			 * During attaching we found a volume which does not
+			 * exist according to the information in the volume
+			 * table. This must have happened due to an unclean
+			 * reboot while the volume was being removed. Discard
+			 * these eraseblocks.
+			 */
+			ubi_msg("finish volume %d removal", av->vol_id);
+			ubi_remove_av(ai, av);
+		} else if (av) {
+			err = check_av(vol, av);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_read_volume_table - read the volume table.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function reads volume table, checks it, recover from errors if needed,
+ * or creates it if needed. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	int i, err;
+	struct ubi_ainf_volume *av;
+
+	empty_vtbl_record.crc = cpu_to_be32(0xf116c36b);
+
+	/*
+	 * The number of supported volumes is limited by the eraseblock size
+	 * and by the UBI_MAX_VOLUMES constant.
+	 */
+	ubi->vtbl_slots = ubi->leb_size / UBI_VTBL_RECORD_SIZE;
+	if (ubi->vtbl_slots > UBI_MAX_VOLUMES)
+		ubi->vtbl_slots = UBI_MAX_VOLUMES;
+
+	ubi->vtbl_size = ubi->vtbl_slots * UBI_VTBL_RECORD_SIZE;
+	ubi->vtbl_size = ALIGN(ubi->vtbl_size, ubi->min_io_size);
+
+	av = ubi_find_av(ai, UBI_LAYOUT_VOLUME_ID);
+	if (!av) {
+		/*
+		 * No logical eraseblocks belonging to the layout volume were
+		 * found. This could mean that the flash is just empty. In
+		 * this case we create empty layout volume.
+		 *
+		 * But if flash is not empty this must be a corruption or the
+		 * MTD device just contains garbage.
+		 */
+		if (ai->is_empty) {
+			ubi->vtbl = create_empty_lvol(ubi, ai);
+			if (IS_ERR(ubi->vtbl))
+				return PTR_ERR(ubi->vtbl);
+		} else {
+			ubi_err("the layout volume was not found");
+			return -EINVAL;
+		}
+	} else {
+		if (av->leb_count > UBI_LAYOUT_VOLUME_EBS) {
+			/* This must not happen with proper UBI images */
+			ubi_err("too many LEBs (%d) in layout volume",
+				av->leb_count);
+			return -EINVAL;
+		}
+
+		ubi->vtbl = process_lvol(ubi, ai, av);
+		if (IS_ERR(ubi->vtbl))
+			return PTR_ERR(ubi->vtbl);
+	}
+
+	ubi->avail_pebs = ubi->good_peb_count - ubi->corr_peb_count;
+
+	/*
+	 * The layout volume is OK, initialize the corresponding in-RAM data
+	 * structures.
+	 */
+	err = init_volumes(ubi, ai, ubi->vtbl);
+	if (err)
+		goto out_free;
+
+	/*
+	 * Make sure that the attaching information is consistent to the
+	 * information stored in the volume table.
+	 */
+	err = check_attaching_info(ubi, ai);
+	if (err)
+		goto out_free;
+
+	return 0;
+
+out_free:
+	vfree(ubi->vtbl);
+	for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
+		kfree(ubi->volumes[i]);
+		ubi->volumes[i] = NULL;
+	}
+	return err;
+}
+
+/**
+ * self_vtbl_check - check volume table.
+ * @ubi: UBI device description object
+ */
+static void self_vtbl_check(const struct ubi_device *ubi)
+{
+	if (!ubi_dbg_chk_gen(ubi))
+		return;
+
+	if (vtbl_check(ubi, ubi->vtbl)) {
+		ubi_err("self-check failed");
+		BUG();
+	}
+}