vtbl.c

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/*
 * 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/crc32.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <asm/div64.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;

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;
}

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;
}

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++) {
        cond_resched();

        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;
}

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);
    kmem_cache_free(ai->aeb_slab_cache, 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;
    }
    kmem_cache_free(ai->aeb_slab_cache, new_aeb);
out_free:
    ubi_free_vid_hdr(ubi, vid_hdr);
    return err;

}

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);
}

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;
}

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++) {
        cond_resched();

        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;
}

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;
}

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++) {
        cond_resched();

        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;
}

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;
}

static void self_vtbl_check(const struct ubi_device *ubi)
{
    if (!ubi->dbg->chk_gen)
        return;

    if (vtbl_check(ubi, ubi->vtbl)) {
        ubi_err("self-check failed");
        BUG();
    }
}