eba.c

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/*
 * 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)
 */

/*
 * The UBI Eraseblock Association (EBA) sub-system.
 *
 * This sub-system is responsible for I/O to/from logical eraseblock.
 *
 * Although in this implementation the EBA table is fully kept and managed in
 * RAM, which assumes poor scalability, it might be (partially) maintained on
 * flash in future implementations.
 *
 * The EBA sub-system implements per-logical eraseblock locking. Before
 * accessing a logical eraseblock it is locked for reading or writing. The
 * per-logical eraseblock locking is implemented by means of the lock tree. The
 * lock tree is an RB-tree which refers all the currently locked logical
 * eraseblocks. The lock tree elements are &struct ubi_ltree_entry objects.
 * They are indexed by (@vol_id, @lnum) pairs.
 *
 * EBA also maintains the global sequence counter which is incremented each
 * time a logical eraseblock is mapped to a physical eraseblock and it is
 * stored in the volume identifier header. This means that each VID header has
 * a unique sequence number. The sequence number is only increased an we assume
 * 64 bits is enough to never overflow.
 */

#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/err.h>
#include "ubi.h"

/* Number of physical eraseblocks reserved for atomic LEB change operation */
#define EBA_RESERVED_PEBS 1

unsigned long long ubi_next_sqnum(struct ubi_device *ubi)
{
    unsigned long long sqnum;

    spin_lock(&ubi->ltree_lock);
    sqnum = ubi->global_sqnum++;
    spin_unlock(&ubi->ltree_lock);

    return sqnum;
}

static int ubi_get_compat(const struct ubi_device *ubi, int vol_id)
{
    if (vol_id == UBI_LAYOUT_VOLUME_ID)
        return UBI_LAYOUT_VOLUME_COMPAT;
    return 0;
}

static struct ubi_ltree_entry *ltree_lookup(struct ubi_device *ubi, int vol_id,
                        int lnum)
{
    struct rb_node *p;

    p = ubi->ltree.rb_node;
    while (p) {
        struct ubi_ltree_entry *le;

        le = rb_entry(p, struct ubi_ltree_entry, rb);

        if (vol_id < le->vol_id)
            p = p->rb_left;
        else if (vol_id > le->vol_id)
            p = p->rb_right;
        else {
            if (lnum < le->lnum)
                p = p->rb_left;
            else if (lnum > le->lnum)
                p = p->rb_right;
            else
                return le;
        }
    }

    return NULL;
}

static struct ubi_ltree_entry *ltree_add_entry(struct ubi_device *ubi,
                           int vol_id, int lnum)
{
    struct ubi_ltree_entry *le, *le1, *le_free;

    le = kmalloc(sizeof(struct ubi_ltree_entry), GFP_NOFS);
    if (!le)
        return ERR_PTR(-ENOMEM);

    le->users = 0;
    init_rwsem(&le->mutex);
    le->vol_id = vol_id;
    le->lnum = lnum;

    spin_lock(&ubi->ltree_lock);
    le1 = ltree_lookup(ubi, vol_id, lnum);

    if (le1) {
        /*
         * This logical eraseblock is already locked. The newly
         * allocated lock entry is not needed.
         */
        le_free = le;
        le = le1;
    } else {
        struct rb_node **p, *parent = NULL;

        /*
         * No lock entry, add the newly allocated one to the
         * @ubi->ltree RB-tree.
         */
        le_free = NULL;

        p = &ubi->ltree.rb_node;
        while (*p) {
            parent = *p;
            le1 = rb_entry(parent, struct ubi_ltree_entry, rb);

            if (vol_id < le1->vol_id)
                p = &(*p)->rb_left;
            else if (vol_id > le1->vol_id)
                p = &(*p)->rb_right;
            else {
                ubi_assert(lnum != le1->lnum);
                if (lnum < le1->lnum)
                    p = &(*p)->rb_left;
                else
                    p = &(*p)->rb_right;
            }
        }

        rb_link_node(&le->rb, parent, p);
        rb_insert_color(&le->rb, &ubi->ltree);
    }
    le->users += 1;
    spin_unlock(&ubi->ltree_lock);

    kfree(le_free);
    return le;
}

static int leb_read_lock(struct ubi_device *ubi, int vol_id, int lnum)
{
    struct ubi_ltree_entry *le;

    le = ltree_add_entry(ubi, vol_id, lnum);
    if (IS_ERR(le))
        return PTR_ERR(le);
    down_read(&le->mutex);
    return 0;
}

static void leb_read_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
    struct ubi_ltree_entry *le;

    spin_lock(&ubi->ltree_lock);
    le = ltree_lookup(ubi, vol_id, lnum);
    le->users -= 1;
    ubi_assert(le->users >= 0);
    up_read(&le->mutex);
    if (le->users == 0) {
        rb_erase(&le->rb, &ubi->ltree);
        kfree(le);
    }
    spin_unlock(&ubi->ltree_lock);
}

static int leb_write_lock(struct ubi_device *ubi, int vol_id, int lnum)
{
    struct ubi_ltree_entry *le;

    le = ltree_add_entry(ubi, vol_id, lnum);
    if (IS_ERR(le))
        return PTR_ERR(le);
    down_write(&le->mutex);
    return 0;
}

static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
{
    struct ubi_ltree_entry *le;

    le = ltree_add_entry(ubi, vol_id, lnum);
    if (IS_ERR(le))
        return PTR_ERR(le);
    if (down_write_trylock(&le->mutex))
        return 0;

    /* Contention, cancel */
    spin_lock(&ubi->ltree_lock);
    le->users -= 1;
    ubi_assert(le->users >= 0);
    if (le->users == 0) {
        rb_erase(&le->rb, &ubi->ltree);
        kfree(le);
    }
    spin_unlock(&ubi->ltree_lock);

    return 1;
}

static void leb_write_unlock(struct ubi_device *ubi, int vol_id, int lnum)
{
    struct ubi_ltree_entry *le;

    spin_lock(&ubi->ltree_lock);
    le = ltree_lookup(ubi, vol_id, lnum);
    le->users -= 1;
    ubi_assert(le->users >= 0);
    up_write(&le->mutex);
    if (le->users == 0) {
        rb_erase(&le->rb, &ubi->ltree);
        kfree(le);
    }
    spin_unlock(&ubi->ltree_lock);
}

int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
              int lnum)
{
    int err, pnum, vol_id = vol->vol_id;

    if (ubi->ro_mode)
        return -EROFS;

    err = leb_write_lock(ubi, vol_id, lnum);
    if (err)
        return err;

    pnum = vol->eba_tbl[lnum];
    if (pnum < 0)
        /* This logical eraseblock is already unmapped */
        goto out_unlock;

    dbg_eba("erase LEB %d:%d, PEB %d", vol_id, lnum, pnum);

    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = UBI_LEB_UNMAPPED;
    up_read(&ubi->fm_sem);
    err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 0);

out_unlock:
    leb_write_unlock(ubi, vol_id, lnum);
    return err;
}

int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
             void *buf, int offset, int len, int check)
{
    int err, pnum, scrub = 0, vol_id = vol->vol_id;
    struct ubi_vid_hdr *vid_hdr;
    uint32_t uninitialized_var(crc);

    err = leb_read_lock(ubi, vol_id, lnum);
    if (err)
        return err;

    pnum = vol->eba_tbl[lnum];
    if (pnum < 0) {
        /*
         * The logical eraseblock is not mapped, fill the whole buffer
         * with 0xFF bytes. The exception is static volumes for which
         * it is an error to read unmapped logical eraseblocks.
         */
        dbg_eba("read %d bytes from offset %d of LEB %d:%d (unmapped)",
            len, offset, vol_id, lnum);
        leb_read_unlock(ubi, vol_id, lnum);
        ubi_assert(vol->vol_type != UBI_STATIC_VOLUME);
        memset(buf, 0xFF, len);
        return 0;
    }

    dbg_eba("read %d bytes from offset %d of LEB %d:%d, PEB %d",
        len, offset, vol_id, lnum, pnum);

    if (vol->vol_type == UBI_DYNAMIC_VOLUME)
        check = 0;

retry:
    if (check) {
        vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
        if (!vid_hdr) {
            err = -ENOMEM;
            goto out_unlock;
        }

        err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
        if (err && err != UBI_IO_BITFLIPS) {
            if (err > 0) {
                /*
                 * The header is either absent or corrupted.
                 * The former case means there is a bug -
                 * switch to read-only mode just in case.
                 * The latter case means a real corruption - we
                 * may try to recover data. FIXME: but this is
                 * not implemented.
                 */
                if (err == UBI_IO_BAD_HDR_EBADMSG ||
                    err == UBI_IO_BAD_HDR) {
                    ubi_warn("corrupted VID header at PEB %d, LEB %d:%d",
                         pnum, vol_id, lnum);
                    err = -EBADMSG;
                } else
                    ubi_ro_mode(ubi);
            }
            goto out_free;
        } else if (err == UBI_IO_BITFLIPS)
            scrub = 1;

        ubi_assert(lnum < be32_to_cpu(vid_hdr->used_ebs));
        ubi_assert(len == be32_to_cpu(vid_hdr->data_size));

        crc = be32_to_cpu(vid_hdr->data_crc);
        ubi_free_vid_hdr(ubi, vid_hdr);
    }

    err = ubi_io_read_data(ubi, buf, pnum, offset, len);
    if (err) {
        if (err == UBI_IO_BITFLIPS) {
            scrub = 1;
            err = 0;
        } else if (mtd_is_eccerr(err)) {
            if (vol->vol_type == UBI_DYNAMIC_VOLUME)
                goto out_unlock;
            scrub = 1;
            if (!check) {
                ubi_msg("force data checking");
                check = 1;
                goto retry;
            }
        } else
            goto out_unlock;
    }

    if (check) {
        uint32_t crc1 = crc32(UBI_CRC32_INIT, buf, len);
        if (crc1 != crc) {
            ubi_warn("CRC error: calculated %#08x, must be %#08x",
                 crc1, crc);
            err = -EBADMSG;
            goto out_unlock;
        }
    }

    if (scrub)
        err = ubi_wl_scrub_peb(ubi, pnum);

    leb_read_unlock(ubi, vol_id, lnum);
    return err;

out_free:
    ubi_free_vid_hdr(ubi, vid_hdr);
out_unlock:
    leb_read_unlock(ubi, vol_id, lnum);
    return err;
}

static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
               const void *buf, int offset, int len)
{
    int err, idx = vol_id2idx(ubi, vol_id), new_pnum, data_size, tries = 0;
    struct ubi_volume *vol = ubi->volumes[idx];
    struct ubi_vid_hdr *vid_hdr;

    vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
    if (!vid_hdr)
        return -ENOMEM;

retry:
    new_pnum = ubi_wl_get_peb(ubi);
    if (new_pnum < 0) {
        ubi_free_vid_hdr(ubi, vid_hdr);
        return new_pnum;
    }

    ubi_msg("recover PEB %d, move data to PEB %d", pnum, new_pnum);

    err = ubi_io_read_vid_hdr(ubi, pnum, vid_hdr, 1);
    if (err && err != UBI_IO_BITFLIPS) {
        if (err > 0)
            err = -EIO;
        goto out_put;
    }

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
    if (err)
        goto write_error;

    data_size = offset + len;
    mutex_lock(&ubi->buf_mutex);
    memset(ubi->peb_buf + offset, 0xFF, len);

    /* Read everything before the area where the write failure happened */
    if (offset > 0) {
        err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, offset);
        if (err && err != UBI_IO_BITFLIPS)
            goto out_unlock;
    }

    memcpy(ubi->peb_buf + offset, buf, len);

    err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
    if (err) {
        mutex_unlock(&ubi->buf_mutex);
        goto write_error;
    }

    mutex_unlock(&ubi->buf_mutex);
    ubi_free_vid_hdr(ubi, vid_hdr);

    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = new_pnum;
    up_read(&ubi->fm_sem);
    ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);

    ubi_msg("data was successfully recovered");
    return 0;

out_unlock:
    mutex_unlock(&ubi->buf_mutex);
out_put:
    ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
    ubi_free_vid_hdr(ubi, vid_hdr);
    return err;

write_error:
    /*
     * Bad luck? This physical eraseblock is bad too? Crud. Let's try to
     * get another one.
     */
    ubi_warn("failed to write to PEB %d", new_pnum);
    ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
    if (++tries > UBI_IO_RETRIES) {
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }
    ubi_msg("try again");
    goto retry;
}

int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
              const void *buf, int offset, int len)
{
    int err, pnum, tries = 0, vol_id = vol->vol_id;
    struct ubi_vid_hdr *vid_hdr;

    if (ubi->ro_mode)
        return -EROFS;

    err = leb_write_lock(ubi, vol_id, lnum);
    if (err)
        return err;

    pnum = vol->eba_tbl[lnum];
    if (pnum >= 0) {
        dbg_eba("write %d bytes at offset %d of LEB %d:%d, PEB %d",
            len, offset, vol_id, lnum, pnum);

        err = ubi_io_write_data(ubi, buf, pnum, offset, len);
        if (err) {
            ubi_warn("failed to write data to PEB %d", pnum);
            if (err == -EIO && ubi->bad_allowed)
                err = recover_peb(ubi, pnum, vol_id, lnum, buf,
                          offset, len);
            if (err)
                ubi_ro_mode(ubi);
        }
        leb_write_unlock(ubi, vol_id, lnum);
        return err;
    }

    /*
     * The logical eraseblock is not mapped. We have to get a free physical
     * eraseblock and write the volume identifier header there first.
     */
    vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
    if (!vid_hdr) {
        leb_write_unlock(ubi, vol_id, lnum);
        return -ENOMEM;
    }

    vid_hdr->vol_type = UBI_VID_DYNAMIC;
    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    vid_hdr->vol_id = cpu_to_be32(vol_id);
    vid_hdr->lnum = cpu_to_be32(lnum);
    vid_hdr->compat = ubi_get_compat(ubi, vol_id);
    vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

retry:
    pnum = ubi_wl_get_peb(ubi);
    if (pnum < 0) {
        ubi_free_vid_hdr(ubi, vid_hdr);
        leb_write_unlock(ubi, vol_id, lnum);
        return pnum;
    }

    dbg_eba("write VID hdr and %d bytes at offset %d of LEB %d:%d, PEB %d",
        len, offset, vol_id, lnum, pnum);

    err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
    if (err) {
        ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
             vol_id, lnum, pnum);
        goto write_error;
    }

    if (len) {
        err = ubi_io_write_data(ubi, buf, pnum, offset, len);
        if (err) {
            ubi_warn("failed to write %d bytes at offset %d of LEB %d:%d, PEB %d",
                 len, offset, vol_id, lnum, pnum);
            goto write_error;
        }
    }

    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = pnum;
    up_read(&ubi->fm_sem);

    leb_write_unlock(ubi, vol_id, lnum);
    ubi_free_vid_hdr(ubi, vid_hdr);
    return 0;

write_error:
    if (err != -EIO || !ubi->bad_allowed) {
        ubi_ro_mode(ubi);
        leb_write_unlock(ubi, vol_id, lnum);
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }

    /*
     * Fortunately, this is the first write operation to this physical
     * eraseblock, so just put it and request a new one. We assume that if
     * this physical eraseblock went bad, the erase code will handle that.
     */
    err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
    if (err || ++tries > UBI_IO_RETRIES) {
        ubi_ro_mode(ubi);
        leb_write_unlock(ubi, vol_id, lnum);
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    ubi_msg("try another PEB");
    goto retry;
}

int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
             int lnum, const void *buf, int len, int used_ebs)
{
    int err, pnum, tries = 0, data_size = len, vol_id = vol->vol_id;
    struct ubi_vid_hdr *vid_hdr;
    uint32_t crc;

    if (ubi->ro_mode)
        return -EROFS;

    if (lnum == used_ebs - 1)
        /* If this is the last LEB @len may be unaligned */
        len = ALIGN(data_size, ubi->min_io_size);
    else
        ubi_assert(!(len & (ubi->min_io_size - 1)));

    vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
    if (!vid_hdr)
        return -ENOMEM;

    err = leb_write_lock(ubi, vol_id, lnum);
    if (err) {
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    vid_hdr->vol_id = cpu_to_be32(vol_id);
    vid_hdr->lnum = cpu_to_be32(lnum);
    vid_hdr->compat = ubi_get_compat(ubi, vol_id);
    vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

    crc = crc32(UBI_CRC32_INIT, buf, data_size);
    vid_hdr->vol_type = UBI_VID_STATIC;
    vid_hdr->data_size = cpu_to_be32(data_size);
    vid_hdr->used_ebs = cpu_to_be32(used_ebs);
    vid_hdr->data_crc = cpu_to_be32(crc);

retry:
    pnum = ubi_wl_get_peb(ubi);
    if (pnum < 0) {
        ubi_free_vid_hdr(ubi, vid_hdr);
        leb_write_unlock(ubi, vol_id, lnum);
        return pnum;
    }

    dbg_eba("write VID hdr and %d bytes at LEB %d:%d, PEB %d, used_ebs %d",
        len, vol_id, lnum, pnum, used_ebs);

    err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
    if (err) {
        ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
             vol_id, lnum, pnum);
        goto write_error;
    }

    err = ubi_io_write_data(ubi, buf, pnum, 0, len);
    if (err) {
        ubi_warn("failed to write %d bytes of data to PEB %d",
             len, pnum);
        goto write_error;
    }

    ubi_assert(vol->eba_tbl[lnum] < 0);
    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = pnum;
    up_read(&ubi->fm_sem);

    leb_write_unlock(ubi, vol_id, lnum);
    ubi_free_vid_hdr(ubi, vid_hdr);
    return 0;

write_error:
    if (err != -EIO || !ubi->bad_allowed) {
        /*
         * This flash device does not admit of bad eraseblocks or
         * something nasty and unexpected happened. Switch to read-only
         * mode just in case.
         */
        ubi_ro_mode(ubi);
        leb_write_unlock(ubi, vol_id, lnum);
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }

    err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
    if (err || ++tries > UBI_IO_RETRIES) {
        ubi_ro_mode(ubi);
        leb_write_unlock(ubi, vol_id, lnum);
        ubi_free_vid_hdr(ubi, vid_hdr);
        return err;
    }

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    ubi_msg("try another PEB");
    goto retry;
}

/*
 * ubi_eba_atomic_leb_change - change logical eraseblock atomically.
 * @ubi: UBI device description object
 * @vol: volume description object
 * @lnum: logical eraseblock number
 * @buf: data to write
 * @len: how many bytes to write
 *
 * This function changes the contents of a logical eraseblock atomically. @buf
 * has to contain new logical eraseblock data, and @len - the length of the
 * data, which has to be aligned. This function guarantees that in case of an
 * unclean reboot the old contents is preserved. Returns zero in case of
 * success and a negative error code in case of failure.
 *
 * UBI reserves one LEB for the "atomic LEB change" operation, so only one
 * LEB change may be done at a time. This is ensured by @ubi->alc_mutex.
 */
int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
                  int lnum, const void *buf, int len)
{
    int err, pnum, tries = 0, vol_id = vol->vol_id;
    struct ubi_vid_hdr *vid_hdr;
    uint32_t crc;

    if (ubi->ro_mode)
        return -EROFS;

    if (len == 0) {
        /*
         * Special case when data length is zero. In this case the LEB
         * has to be unmapped and mapped somewhere else.
         */
        err = ubi_eba_unmap_leb(ubi, vol, lnum);
        if (err)
            return err;
        return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
    }

    vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
    if (!vid_hdr)
        return -ENOMEM;

    mutex_lock(&ubi->alc_mutex);
    err = leb_write_lock(ubi, vol_id, lnum);
    if (err)
        goto out_mutex;

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    vid_hdr->vol_id = cpu_to_be32(vol_id);
    vid_hdr->lnum = cpu_to_be32(lnum);
    vid_hdr->compat = ubi_get_compat(ubi, vol_id);
    vid_hdr->data_pad = cpu_to_be32(vol->data_pad);

    crc = crc32(UBI_CRC32_INIT, buf, len);
    vid_hdr->vol_type = UBI_VID_DYNAMIC;
    vid_hdr->data_size = cpu_to_be32(len);
    vid_hdr->copy_flag = 1;
    vid_hdr->data_crc = cpu_to_be32(crc);

retry:
    pnum = ubi_wl_get_peb(ubi);
    if (pnum < 0) {
        err = pnum;
        goto out_leb_unlock;
    }

    dbg_eba("change LEB %d:%d, PEB %d, write VID hdr to PEB %d",
        vol_id, lnum, vol->eba_tbl[lnum], pnum);

    err = ubi_io_write_vid_hdr(ubi, pnum, vid_hdr);
    if (err) {
        ubi_warn("failed to write VID header to LEB %d:%d, PEB %d",
             vol_id, lnum, pnum);
        goto write_error;
    }

    err = ubi_io_write_data(ubi, buf, pnum, 0, len);
    if (err) {
        ubi_warn("failed to write %d bytes of data to PEB %d",
             len, pnum);
        goto write_error;
    }

    if (vol->eba_tbl[lnum] >= 0) {
        err = ubi_wl_put_peb(ubi, vol_id, lnum, vol->eba_tbl[lnum], 0);
        if (err)
            goto out_leb_unlock;
    }

    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = pnum;
    up_read(&ubi->fm_sem);

out_leb_unlock:
    leb_write_unlock(ubi, vol_id, lnum);
out_mutex:
    mutex_unlock(&ubi->alc_mutex);
    ubi_free_vid_hdr(ubi, vid_hdr);
    return err;

write_error:
    if (err != -EIO || !ubi->bad_allowed) {
        /*
         * This flash device does not admit of bad eraseblocks or
         * something nasty and unexpected happened. Switch to read-only
         * mode just in case.
         */
        ubi_ro_mode(ubi);
        goto out_leb_unlock;
    }

    err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
    if (err || ++tries > UBI_IO_RETRIES) {
        ubi_ro_mode(ubi);
        goto out_leb_unlock;
    }

    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
    ubi_msg("try another PEB");
    goto retry;
}

static int is_error_sane(int err)
{
    if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
        err == UBI_IO_BAD_HDR_EBADMSG || err == -ETIMEDOUT)
        return 0;
    return 1;
}

int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
             struct ubi_vid_hdr *vid_hdr)
{
    int err, vol_id, lnum, data_size, aldata_size, idx;
    struct ubi_volume *vol;
    uint32_t crc;

    vol_id = be32_to_cpu(vid_hdr->vol_id);
    lnum = be32_to_cpu(vid_hdr->lnum);

    dbg_wl("copy LEB %d:%d, PEB %d to PEB %d", vol_id, lnum, from, to);

    if (vid_hdr->vol_type == UBI_VID_STATIC) {
        data_size = be32_to_cpu(vid_hdr->data_size);
        aldata_size = ALIGN(data_size, ubi->min_io_size);
    } else
        data_size = aldata_size =
                ubi->leb_size - be32_to_cpu(vid_hdr->data_pad);

    idx = vol_id2idx(ubi, vol_id);
    spin_lock(&ubi->volumes_lock);
    /*
     * Note, we may race with volume deletion, which means that the volume
     * this logical eraseblock belongs to might be being deleted. Since the
     * volume deletion un-maps all the volume's logical eraseblocks, it will
     * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
     */
    vol = ubi->volumes[idx];
    spin_unlock(&ubi->volumes_lock);
    if (!vol) {
        /* No need to do further work, cancel */
        dbg_wl("volume %d is being removed, cancel", vol_id);
        return MOVE_CANCEL_RACE;
    }

    /*
     * We do not want anybody to write to this logical eraseblock while we
     * are moving it, so lock it.
     *
     * Note, we are using non-waiting locking here, because we cannot sleep
     * on the LEB, since it may cause deadlocks. Indeed, imagine a task is
     * unmapping the LEB which is mapped to the PEB we are going to move
     * (@from). This task locks the LEB and goes sleep in the
     * 'ubi_wl_put_peb()' function on the @ubi->move_mutex. In turn, we are
     * holding @ubi->move_mutex and go sleep on the LEB lock. So, if the
     * LEB is already locked, we just do not move it and return
     * %MOVE_RETRY. Note, we do not return %MOVE_CANCEL_RACE here because
     * we do not know the reasons of the contention - it may be just a
     * normal I/O on this LEB, so we want to re-try.
     */
    err = leb_write_trylock(ubi, vol_id, lnum);
    if (err) {
        dbg_wl("contention on LEB %d:%d, cancel", vol_id, lnum);
        return MOVE_RETRY;
    }

    /*
     * The LEB might have been put meanwhile, and the task which put it is
     * probably waiting on @ubi->move_mutex. No need to continue the work,
     * cancel it.
     */
    if (vol->eba_tbl[lnum] != from) {
        dbg_wl("LEB %d:%d is no longer mapped to PEB %d, mapped to PEB %d, cancel",
               vol_id, lnum, from, vol->eba_tbl[lnum]);
        err = MOVE_CANCEL_RACE;
        goto out_unlock_leb;
    }

    /*
     * OK, now the LEB is locked and we can safely start moving it. Since
     * this function utilizes the @ubi->peb_buf buffer which is shared
     * with some other functions - we lock the buffer by taking the
     * @ubi->buf_mutex.
     */
    mutex_lock(&ubi->buf_mutex);
    dbg_wl("read %d bytes of data", aldata_size);
    err = ubi_io_read_data(ubi, ubi->peb_buf, from, 0, aldata_size);
    if (err && err != UBI_IO_BITFLIPS) {
        ubi_warn("error %d while reading data from PEB %d",
             err, from);
        err = MOVE_SOURCE_RD_ERR;
        goto out_unlock_buf;
    }

    /*
     * Now we have got to calculate how much data we have to copy. In
     * case of a static volume it is fairly easy - the VID header contains
     * the data size. In case of a dynamic volume it is more difficult - we
     * have to read the contents, cut 0xFF bytes from the end and copy only
     * the first part. We must do this to avoid writing 0xFF bytes as it
     * may have some side-effects. And not only this. It is important not
     * to include those 0xFFs to CRC because later the they may be filled
     * by data.
     */
    if (vid_hdr->vol_type == UBI_VID_DYNAMIC)
        aldata_size = data_size =
            ubi_calc_data_len(ubi, ubi->peb_buf, data_size);

    cond_resched();
    crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
    cond_resched();

    /*
     * It may turn out to be that the whole @from physical eraseblock
     * contains only 0xFF bytes. Then we have to only write the VID header
     * and do not write any data. This also means we should not set
     * @vid_hdr->copy_flag, @vid_hdr->data_size, and @vid_hdr->data_crc.
     */
    if (data_size > 0) {
        vid_hdr->copy_flag = 1;
        vid_hdr->data_size = cpu_to_be32(data_size);
        vid_hdr->data_crc = cpu_to_be32(crc);
    }
    vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));

    err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
    if (err) {
        if (err == -EIO)
            err = MOVE_TARGET_WR_ERR;
        goto out_unlock_buf;
    }

    cond_resched();

    /* Read the VID header back and check if it was written correctly */
    err = ubi_io_read_vid_hdr(ubi, to, vid_hdr, 1);
    if (err) {
        if (err != UBI_IO_BITFLIPS) {
            ubi_warn("error %d while reading VID header back from PEB %d",
                 err, to);
            if (is_error_sane(err))
                err = MOVE_TARGET_RD_ERR;
        } else
            err = MOVE_TARGET_BITFLIPS;
        goto out_unlock_buf;
    }

    if (data_size > 0) {
        err = ubi_io_write_data(ubi, ubi->peb_buf, to, 0, aldata_size);
        if (err) {
            if (err == -EIO)
                err = MOVE_TARGET_WR_ERR;
            goto out_unlock_buf;
        }

        cond_resched();

        /*
         * We've written the data and are going to read it back to make
         * sure it was written correctly.
         */
        memset(ubi->peb_buf, 0xFF, aldata_size);
        err = ubi_io_read_data(ubi, ubi->peb_buf, to, 0, aldata_size);
        if (err) {
            if (err != UBI_IO_BITFLIPS) {
                ubi_warn("error %d while reading data back from PEB %d",
                     err, to);
                if (is_error_sane(err))
                    err = MOVE_TARGET_RD_ERR;
            } else
                err = MOVE_TARGET_BITFLIPS;
            goto out_unlock_buf;
        }

        cond_resched();

        if (crc != crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size)) {
            ubi_warn("read data back from PEB %d and it is different",
                 to);
            err = -EINVAL;
            goto out_unlock_buf;
        }
    }

    ubi_assert(vol->eba_tbl[lnum] == from);
    down_read(&ubi->fm_sem);
    vol->eba_tbl[lnum] = to;
    up_read(&ubi->fm_sem);

out_unlock_buf:
    mutex_unlock(&ubi->buf_mutex);
out_unlock_leb:
    leb_write_unlock(ubi, vol_id, lnum);
    return err;
}

static void print_rsvd_warning(struct ubi_device *ubi,
                   struct ubi_attach_info *ai)
{
    /*
     * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
     * large number to distinguish between newly flashed and used images.
     */
    if (ai->max_sqnum > (1 << 18)) {
        int min = ubi->beb_rsvd_level / 10;

        if (!min)
            min = 1;
        if (ubi->beb_rsvd_pebs > min)
            return;
    }

    ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d, need %d",
         ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
    if (ubi->corr_peb_count)
        ubi_warn("%d PEBs are corrupted and not used",
             ubi->corr_peb_count);
}

int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
           struct ubi_attach_info *ai_scan)
{
    int i, j, num_volumes, ret = 0;
    int **scan_eba, **fm_eba;
    struct ubi_ainf_volume *av;
    struct ubi_volume *vol;
    struct ubi_ainf_peb *aeb;
    struct rb_node *rb;

    num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;

    scan_eba = kmalloc(sizeof(*scan_eba) * num_volumes, GFP_KERNEL);
    if (!scan_eba)
        return -ENOMEM;

    fm_eba = kmalloc(sizeof(*fm_eba) * num_volumes, GFP_KERNEL);
    if (!fm_eba) {
        kfree(scan_eba);
        return -ENOMEM;
    }

    for (i = 0; i < num_volumes; i++) {
        vol = ubi->volumes[i];
        if (!vol)
            continue;

        scan_eba[i] = kmalloc(vol->reserved_pebs * sizeof(**scan_eba),
                      GFP_KERNEL);
        if (!scan_eba[i]) {
            ret = -ENOMEM;
            goto out_free;
        }

        fm_eba[i] = kmalloc(vol->reserved_pebs * sizeof(**fm_eba),
                    GFP_KERNEL);
        if (!fm_eba[i]) {
            ret = -ENOMEM;
            goto out_free;
        }

        for (j = 0; j < vol->reserved_pebs; j++)
            scan_eba[i][j] = fm_eba[i][j] = UBI_LEB_UNMAPPED;

        av = ubi_find_av(ai_scan, idx2vol_id(ubi, i));
        if (!av)
            continue;

        ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
            scan_eba[i][aeb->lnum] = aeb->pnum;

        av = ubi_find_av(ai_fastmap, idx2vol_id(ubi, i));
        if (!av)
            continue;

        ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
            fm_eba[i][aeb->lnum] = aeb->pnum;

        for (j = 0; j < vol->reserved_pebs; j++) {
            if (scan_eba[i][j] != fm_eba[i][j]) {
                if (scan_eba[i][j] == UBI_LEB_UNMAPPED ||
                    fm_eba[i][j] == UBI_LEB_UNMAPPED)
                    continue;

                ubi_err("LEB:%i:%i is PEB:%i instead of %i!",
                    vol->vol_id, i, fm_eba[i][j],
                    scan_eba[i][j]);
                ubi_assert(0);
            }
        }
    }

out_free:
    for (i = 0; i < num_volumes; i++) {
        if (!ubi->volumes[i])
            continue;

        kfree(scan_eba[i]);
        kfree(fm_eba[i]);
    }

    kfree(scan_eba);
    kfree(fm_eba);
    return ret;
}

int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
{
    int i, j, err, num_volumes;
    struct ubi_ainf_volume *av;
    struct ubi_volume *vol;
    struct ubi_ainf_peb *aeb;
    struct rb_node *rb;

    dbg_eba("initialize EBA sub-system");

    spin_lock_init(&ubi->ltree_lock);
    mutex_init(&ubi->alc_mutex);
    ubi->ltree = RB_ROOT;

    ubi->global_sqnum = ai->max_sqnum + 1;
    num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;

    for (i = 0; i < num_volumes; i++) {
        vol = ubi->volumes[i];
        if (!vol)
            continue;

        cond_resched();

        vol->eba_tbl = kmalloc(vol->reserved_pebs * sizeof(int),
                       GFP_KERNEL);
        if (!vol->eba_tbl) {
            err = -ENOMEM;
            goto out_free;
        }

        for (j = 0; j < vol->reserved_pebs; j++)
            vol->eba_tbl[j] = UBI_LEB_UNMAPPED;

        av = ubi_find_av(ai, idx2vol_id(ubi, i));
        if (!av)
            continue;

        ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
            if (aeb->lnum >= vol->reserved_pebs)
                /*
                 * This may happen in case of an unclean reboot
                 * during re-size.
                 */
                ubi_move_aeb_to_list(av, aeb, &ai->erase);
            vol->eba_tbl[aeb->lnum] = aeb->pnum;
        }
    }

    if (ubi->avail_pebs < EBA_RESERVED_PEBS) {
        ubi_err("no enough physical eraseblocks (%d, need %d)",
            ubi->avail_pebs, EBA_RESERVED_PEBS);
        if (ubi->corr_peb_count)
            ubi_err("%d PEBs are corrupted and not used",
                ubi->corr_peb_count);
        err = -ENOSPC;
        goto out_free;
    }
    ubi->avail_pebs -= EBA_RESERVED_PEBS;
    ubi->rsvd_pebs += EBA_RESERVED_PEBS;

    if (ubi->bad_allowed) {
        ubi_calculate_reserved(ubi);

        if (ubi->avail_pebs < ubi->beb_rsvd_level) {
            /* No enough free physical eraseblocks */
            ubi->beb_rsvd_pebs = ubi->avail_pebs;
            print_rsvd_warning(ubi, ai);
        } else
            ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;

        ubi->avail_pebs -= ubi->beb_rsvd_pebs;
        ubi->rsvd_pebs  += ubi->beb_rsvd_pebs;
    }

    dbg_eba("EBA sub-system is initialized");
    return 0;

out_free:
    for (i = 0; i < num_volumes; i++) {
        if (!ubi->volumes[i])
            continue;
        kfree(ubi->volumes[i]->eba_tbl);
        ubi->volumes[i]->eba_tbl = NULL;
    }
    return err;
}