sb.c

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/*
 * This file is part of UBIFS.
 *
 * Copyright (C) 2006-2008 Nokia Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * 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., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * Authors: Artem Bityutskiy (Битюцкий Артём)
 *          Adrian Hunter
 */

/*
 * This file implements UBIFS superblock. The superblock is stored at the first
 * LEB of the volume and is never changed by UBIFS. Only user-space tools may
 * change it. The superblock node mostly contains geometry information.
 */

#include "ubifs.h"
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/math64.h>

/*
 * Default journal size in logical eraseblocks as a percent of total
 * flash size.
 */
#define DEFAULT_JNL_PERCENT 5

/* Default maximum journal size in bytes */
#define DEFAULT_MAX_JNL (32*1024*1024)

/* Default indexing tree fanout */
#define DEFAULT_FANOUT 8

/* Default number of data journal heads */
#define DEFAULT_JHEADS_CNT 1

/* Default positions of different LEBs in the main area */
#define DEFAULT_IDX_LEB  0
#define DEFAULT_DATA_LEB 1
#define DEFAULT_GC_LEB   2

/* Default number of LEB numbers in LPT's save table */
#define DEFAULT_LSAVE_CNT 256

/* Default reserved pool size as a percent of maximum free space */
#define DEFAULT_RP_PERCENT 5

/* The default maximum size of reserved pool in bytes */
#define DEFAULT_MAX_RP_SIZE (5*1024*1024)

/* Default time granularity in nanoseconds */
#define DEFAULT_TIME_GRAN 1000000000

static int create_default_filesystem(struct ubifs_info *c)
{
    struct ubifs_sb_node *sup;
    struct ubifs_mst_node *mst;
    struct ubifs_idx_node *idx;
    struct ubifs_branch *br;
    struct ubifs_ino_node *ino;
    struct ubifs_cs_node *cs;
    union ubifs_key key;
    int err, tmp, jnl_lebs, log_lebs, max_buds, main_lebs, main_first;
    int lpt_lebs, lpt_first, orph_lebs, big_lpt, ino_waste, sup_flags = 0;
    int min_leb_cnt = UBIFS_MIN_LEB_CNT;
    long long tmp64, main_bytes;
    __le64 tmp_le64;

    /* Some functions called from here depend on the @c->key_len filed */
    c->key_len = UBIFS_SK_LEN;

    /*
     * First of all, we have to calculate default file-system geometry -
     * log size, journal size, etc.
     */
    if (c->leb_cnt < 0x7FFFFFFF / DEFAULT_JNL_PERCENT)
        /* We can first multiply then divide and have no overflow */
        jnl_lebs = c->leb_cnt * DEFAULT_JNL_PERCENT / 100;
    else
        jnl_lebs = (c->leb_cnt / 100) * DEFAULT_JNL_PERCENT;

    if (jnl_lebs < UBIFS_MIN_JNL_LEBS)
        jnl_lebs = UBIFS_MIN_JNL_LEBS;
    if (jnl_lebs * c->leb_size > DEFAULT_MAX_JNL)
        jnl_lebs = DEFAULT_MAX_JNL / c->leb_size;

    /*
     * The log should be large enough to fit reference nodes for all bud
     * LEBs. Because buds do not have to start from the beginning of LEBs
     * (half of the LEB may contain committed data), the log should
     * generally be larger, make it twice as large.
     */
    tmp = 2 * (c->ref_node_alsz * jnl_lebs) + c->leb_size - 1;
    log_lebs = tmp / c->leb_size;
    /* Plus one LEB reserved for commit */
    log_lebs += 1;
    if (c->leb_cnt - min_leb_cnt > 8) {
        /* And some extra space to allow writes while committing */
        log_lebs += 1;
        min_leb_cnt += 1;
    }

    max_buds = jnl_lebs - log_lebs;
    if (max_buds < UBIFS_MIN_BUD_LEBS)
        max_buds = UBIFS_MIN_BUD_LEBS;

    /*
     * Orphan nodes are stored in a separate area. One node can store a lot
     * of orphan inode numbers, but when new orphan comes we just add a new
     * orphan node. At some point the nodes are consolidated into one
     * orphan node.
     */
    orph_lebs = UBIFS_MIN_ORPH_LEBS;
    if (c->leb_cnt - min_leb_cnt > 1)
        /*
         * For debugging purposes it is better to have at least 2
         * orphan LEBs, because the orphan subsystem would need to do
         * consolidations and would be stressed more.
         */
        orph_lebs += 1;

    main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS - log_lebs;
    main_lebs -= orph_lebs;

    lpt_first = UBIFS_LOG_LNUM + log_lebs;
    c->lsave_cnt = DEFAULT_LSAVE_CNT;
    c->max_leb_cnt = c->leb_cnt;
    err = ubifs_create_dflt_lpt(c, &main_lebs, lpt_first, &lpt_lebs,
                    &big_lpt);
    if (err)
        return err;

    dbg_gen("LEB Properties Tree created (LEBs %d-%d)", lpt_first,
        lpt_first + lpt_lebs - 1);

    main_first = c->leb_cnt - main_lebs;

    /* Create default superblock */
    tmp = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);
    sup = kzalloc(tmp, GFP_KERNEL);
    if (!sup)
        return -ENOMEM;

    tmp64 = (long long)max_buds * c->leb_size;
    if (big_lpt)
        sup_flags |= UBIFS_FLG_BIGLPT;

    sup->ch.node_type  = UBIFS_SB_NODE;
    sup->key_hash      = UBIFS_KEY_HASH_R5;
    sup->flags         = cpu_to_le32(sup_flags);
    sup->min_io_size   = cpu_to_le32(c->min_io_size);
    sup->leb_size      = cpu_to_le32(c->leb_size);
    sup->leb_cnt       = cpu_to_le32(c->leb_cnt);
    sup->max_leb_cnt   = cpu_to_le32(c->max_leb_cnt);
    sup->max_bud_bytes = cpu_to_le64(tmp64);
    sup->log_lebs      = cpu_to_le32(log_lebs);
    sup->lpt_lebs      = cpu_to_le32(lpt_lebs);
    sup->orph_lebs     = cpu_to_le32(orph_lebs);
    sup->jhead_cnt     = cpu_to_le32(DEFAULT_JHEADS_CNT);
    sup->fanout        = cpu_to_le32(DEFAULT_FANOUT);
    sup->lsave_cnt     = cpu_to_le32(c->lsave_cnt);
    sup->fmt_version   = cpu_to_le32(UBIFS_FORMAT_VERSION);
    sup->time_gran     = cpu_to_le32(DEFAULT_TIME_GRAN);
    if (c->mount_opts.override_compr)
        sup->default_compr = cpu_to_le16(c->mount_opts.compr_type);
    else
        sup->default_compr = cpu_to_le16(UBIFS_COMPR_LZO);

    generate_random_uuid(sup->uuid);

    main_bytes = (long long)main_lebs * c->leb_size;
    tmp64 = div_u64(main_bytes * DEFAULT_RP_PERCENT, 100);
    if (tmp64 > DEFAULT_MAX_RP_SIZE)
        tmp64 = DEFAULT_MAX_RP_SIZE;
    sup->rp_size = cpu_to_le64(tmp64);
    sup->ro_compat_version = cpu_to_le32(UBIFS_RO_COMPAT_VERSION);

    err = ubifs_write_node(c, sup, UBIFS_SB_NODE_SZ, 0, 0);
    kfree(sup);
    if (err)
        return err;

    dbg_gen("default superblock created at LEB 0:0");

    /* Create default master node */
    mst = kzalloc(c->mst_node_alsz, GFP_KERNEL);
    if (!mst)
        return -ENOMEM;

    mst->ch.node_type = UBIFS_MST_NODE;
    mst->log_lnum     = cpu_to_le32(UBIFS_LOG_LNUM);
    mst->highest_inum = cpu_to_le64(UBIFS_FIRST_INO);
    mst->cmt_no       = 0;
    mst->root_lnum    = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
    mst->root_offs    = 0;
    tmp = ubifs_idx_node_sz(c, 1);
    mst->root_len     = cpu_to_le32(tmp);
    mst->gc_lnum      = cpu_to_le32(main_first + DEFAULT_GC_LEB);
    mst->ihead_lnum   = cpu_to_le32(main_first + DEFAULT_IDX_LEB);
    mst->ihead_offs   = cpu_to_le32(ALIGN(tmp, c->min_io_size));
    mst->index_size   = cpu_to_le64(ALIGN(tmp, 8));
    mst->lpt_lnum     = cpu_to_le32(c->lpt_lnum);
    mst->lpt_offs     = cpu_to_le32(c->lpt_offs);
    mst->nhead_lnum   = cpu_to_le32(c->nhead_lnum);
    mst->nhead_offs   = cpu_to_le32(c->nhead_offs);
    mst->ltab_lnum    = cpu_to_le32(c->ltab_lnum);
    mst->ltab_offs    = cpu_to_le32(c->ltab_offs);
    mst->lsave_lnum   = cpu_to_le32(c->lsave_lnum);
    mst->lsave_offs   = cpu_to_le32(c->lsave_offs);
    mst->lscan_lnum   = cpu_to_le32(main_first);
    mst->empty_lebs   = cpu_to_le32(main_lebs - 2);
    mst->idx_lebs     = cpu_to_le32(1);
    mst->leb_cnt      = cpu_to_le32(c->leb_cnt);

    /* Calculate lprops statistics */
    tmp64 = main_bytes;
    tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
    tmp64 -= ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
    mst->total_free = cpu_to_le64(tmp64);

    tmp64 = ALIGN(ubifs_idx_node_sz(c, 1), c->min_io_size);
    ino_waste = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size) -
              UBIFS_INO_NODE_SZ;
    tmp64 += ino_waste;
    tmp64 -= ALIGN(ubifs_idx_node_sz(c, 1), 8);
    mst->total_dirty = cpu_to_le64(tmp64);

    /*  The indexing LEB does not contribute to dark space */
    tmp64 = ((long long)(c->main_lebs - 1) * c->dark_wm);
    mst->total_dark = cpu_to_le64(tmp64);

    mst->total_used = cpu_to_le64(UBIFS_INO_NODE_SZ);

    err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0);
    if (err) {
        kfree(mst);
        return err;
    }
    err = ubifs_write_node(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM + 1,
                   0);
    kfree(mst);
    if (err)
        return err;

    dbg_gen("default master node created at LEB %d:0", UBIFS_MST_LNUM);

    /* Create the root indexing node */
    tmp = ubifs_idx_node_sz(c, 1);
    idx = kzalloc(ALIGN(tmp, c->min_io_size), GFP_KERNEL);
    if (!idx)
        return -ENOMEM;

    c->key_fmt = UBIFS_SIMPLE_KEY_FMT;
    c->key_hash = key_r5_hash;

    idx->ch.node_type = UBIFS_IDX_NODE;
    idx->child_cnt = cpu_to_le16(1);
    ino_key_init(c, &key, UBIFS_ROOT_INO);
    br = ubifs_idx_branch(c, idx, 0);
    key_write_idx(c, &key, &br->key);
    br->lnum = cpu_to_le32(main_first + DEFAULT_DATA_LEB);
    br->len  = cpu_to_le32(UBIFS_INO_NODE_SZ);
    err = ubifs_write_node(c, idx, tmp, main_first + DEFAULT_IDX_LEB, 0);
    kfree(idx);
    if (err)
        return err;

    dbg_gen("default root indexing node created LEB %d:0",
        main_first + DEFAULT_IDX_LEB);

    /* Create default root inode */
    tmp = ALIGN(UBIFS_INO_NODE_SZ, c->min_io_size);
    ino = kzalloc(tmp, GFP_KERNEL);
    if (!ino)
        return -ENOMEM;

    ino_key_init_flash(c, &ino->key, UBIFS_ROOT_INO);
    ino->ch.node_type = UBIFS_INO_NODE;
    ino->creat_sqnum = cpu_to_le64(++c->max_sqnum);
    ino->nlink = cpu_to_le32(2);
    tmp_le64 = cpu_to_le64(CURRENT_TIME_SEC.tv_sec);
    ino->atime_sec   = tmp_le64;
    ino->ctime_sec   = tmp_le64;
    ino->mtime_sec   = tmp_le64;
    ino->atime_nsec  = 0;
    ino->ctime_nsec  = 0;
    ino->mtime_nsec  = 0;
    ino->mode = cpu_to_le32(S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO);
    ino->size = cpu_to_le64(UBIFS_INO_NODE_SZ);

    /* Set compression enabled by default */
    ino->flags = cpu_to_le32(UBIFS_COMPR_FL);

    err = ubifs_write_node(c, ino, UBIFS_INO_NODE_SZ,
                   main_first + DEFAULT_DATA_LEB, 0);
    kfree(ino);
    if (err)
        return err;

    dbg_gen("root inode created at LEB %d:0",
        main_first + DEFAULT_DATA_LEB);

    /*
     * The first node in the log has to be the commit start node. This is
     * always the case during normal file-system operation. Write a fake
     * commit start node to the log.
     */
    tmp = ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size);
    cs = kzalloc(tmp, GFP_KERNEL);
    if (!cs)
        return -ENOMEM;

    cs->ch.node_type = UBIFS_CS_NODE;
    err = ubifs_write_node(c, cs, UBIFS_CS_NODE_SZ, UBIFS_LOG_LNUM, 0);
    kfree(cs);

    ubifs_msg("default file-system created");
    return 0;
}

static int validate_sb(struct ubifs_info *c, struct ubifs_sb_node *sup)
{
    long long max_bytes;
    int err = 1, min_leb_cnt;

    if (!c->key_hash) {
        err = 2;
        goto failed;
    }

    if (sup->key_fmt != UBIFS_SIMPLE_KEY_FMT) {
        err = 3;
        goto failed;
    }

    if (le32_to_cpu(sup->min_io_size) != c->min_io_size) {
        ubifs_err("min. I/O unit mismatch: %d in superblock, %d real",
              le32_to_cpu(sup->min_io_size), c->min_io_size);
        goto failed;
    }

    if (le32_to_cpu(sup->leb_size) != c->leb_size) {
        ubifs_err("LEB size mismatch: %d in superblock, %d real",
              le32_to_cpu(sup->leb_size), c->leb_size);
        goto failed;
    }

    if (c->log_lebs < UBIFS_MIN_LOG_LEBS ||
        c->lpt_lebs < UBIFS_MIN_LPT_LEBS ||
        c->orph_lebs < UBIFS_MIN_ORPH_LEBS ||
        c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
        err = 4;
        goto failed;
    }

    /*
     * Calculate minimum allowed amount of main area LEBs. This is very
     * similar to %UBIFS_MIN_LEB_CNT, but we take into account real what we
     * have just read from the superblock.
     */
    min_leb_cnt = UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs;
    min_leb_cnt += c->lpt_lebs + c->orph_lebs + c->jhead_cnt + 6;

    if (c->leb_cnt < min_leb_cnt || c->leb_cnt > c->vi.size) {
        ubifs_err("bad LEB count: %d in superblock, %d on UBI volume, %d minimum required",
              c->leb_cnt, c->vi.size, min_leb_cnt);
        goto failed;
    }

    if (c->max_leb_cnt < c->leb_cnt) {
        ubifs_err("max. LEB count %d less than LEB count %d",
              c->max_leb_cnt, c->leb_cnt);
        goto failed;
    }

    if (c->main_lebs < UBIFS_MIN_MAIN_LEBS) {
        ubifs_err("too few main LEBs count %d, must be at least %d",
              c->main_lebs, UBIFS_MIN_MAIN_LEBS);
        goto failed;
    }

    max_bytes = (long long)c->leb_size * UBIFS_MIN_BUD_LEBS;
    if (c->max_bud_bytes < max_bytes) {
        ubifs_err("too small journal (%lld bytes), must be at least %lld bytes",
              c->max_bud_bytes, max_bytes);
        goto failed;
    }

    max_bytes = (long long)c->leb_size * c->main_lebs;
    if (c->max_bud_bytes > max_bytes) {
        ubifs_err("too large journal size (%lld bytes), only %lld bytes available in the main area",
              c->max_bud_bytes, max_bytes);
        goto failed;
    }

    if (c->jhead_cnt < NONDATA_JHEADS_CNT + 1 ||
        c->jhead_cnt > NONDATA_JHEADS_CNT + UBIFS_MAX_JHEADS) {
        err = 9;
        goto failed;
    }

    if (c->fanout < UBIFS_MIN_FANOUT ||
        ubifs_idx_node_sz(c, c->fanout) > c->leb_size) {
        err = 10;
        goto failed;
    }

    if (c->lsave_cnt < 0 || (c->lsave_cnt > DEFAULT_LSAVE_CNT &&
        c->lsave_cnt > c->max_leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS -
        c->log_lebs - c->lpt_lebs - c->orph_lebs)) {
        err = 11;
        goto failed;
    }

    if (UBIFS_SB_LEBS + UBIFS_MST_LEBS + c->log_lebs + c->lpt_lebs +
        c->orph_lebs + c->main_lebs != c->leb_cnt) {
        err = 12;
        goto failed;
    }

    if (c->default_compr < 0 || c->default_compr >= UBIFS_COMPR_TYPES_CNT) {
        err = 13;
        goto failed;
    }

    if (c->rp_size < 0 || max_bytes < c->rp_size) {
        err = 14;
        goto failed;
    }

    if (le32_to_cpu(sup->time_gran) > 1000000000 ||
        le32_to_cpu(sup->time_gran) < 1) {
        err = 15;
        goto failed;
    }

    return 0;

failed:
    ubifs_err("bad superblock, error %d", err);
    ubifs_dump_node(c, sup);
    return -EINVAL;
}

struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c)
{
    struct ubifs_sb_node *sup;
    int err;

    sup = kmalloc(ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size), GFP_NOFS);
    if (!sup)
        return ERR_PTR(-ENOMEM);

    err = ubifs_read_node(c, sup, UBIFS_SB_NODE, UBIFS_SB_NODE_SZ,
                  UBIFS_SB_LNUM, 0);
    if (err) {
        kfree(sup);
        return ERR_PTR(err);
    }

    return sup;
}

int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup)
{
    int len = ALIGN(UBIFS_SB_NODE_SZ, c->min_io_size);

    ubifs_prepare_node(c, sup, UBIFS_SB_NODE_SZ, 1);
    return ubifs_leb_change(c, UBIFS_SB_LNUM, sup, len);
}

int ubifs_read_superblock(struct ubifs_info *c)
{
    int err, sup_flags;
    struct ubifs_sb_node *sup;

    if (c->empty) {
        err = create_default_filesystem(c);
        if (err)
            return err;
    }

    sup = ubifs_read_sb_node(c);
    if (IS_ERR(sup))
        return PTR_ERR(sup);

    c->fmt_version = le32_to_cpu(sup->fmt_version);
    c->ro_compat_version = le32_to_cpu(sup->ro_compat_version);

    /*
     * The software supports all previous versions but not future versions,
     * due to the unavailability of time-travelling equipment.
     */
    if (c->fmt_version > UBIFS_FORMAT_VERSION) {
        ubifs_assert(!c->ro_media || c->ro_mount);
        if (!c->ro_mount ||
            c->ro_compat_version > UBIFS_RO_COMPAT_VERSION) {
            ubifs_err("on-flash format version is w%d/r%d, but software only supports up to version w%d/r%d",
                  c->fmt_version, c->ro_compat_version,
                  UBIFS_FORMAT_VERSION,
                  UBIFS_RO_COMPAT_VERSION);
            if (c->ro_compat_version <= UBIFS_RO_COMPAT_VERSION) {
                ubifs_msg("only R/O mounting is possible");
                err = -EROFS;
            } else
                err = -EINVAL;
            goto out;
        }

        /*
         * The FS is mounted R/O, and the media format is
         * R/O-compatible with the UBIFS implementation, so we can
         * mount.
         */
        c->rw_incompat = 1;
    }

    if (c->fmt_version < 3) {
        ubifs_err("on-flash format version %d is not supported",
              c->fmt_version);
        err = -EINVAL;
        goto out;
    }

    switch (sup->key_hash) {
    case UBIFS_KEY_HASH_R5:
        c->key_hash = key_r5_hash;
        c->key_hash_type = UBIFS_KEY_HASH_R5;
        break;

    case UBIFS_KEY_HASH_TEST:
        c->key_hash = key_test_hash;
        c->key_hash_type = UBIFS_KEY_HASH_TEST;
        break;
    };

    c->key_fmt = sup->key_fmt;

    switch (c->key_fmt) {
    case UBIFS_SIMPLE_KEY_FMT:
        c->key_len = UBIFS_SK_LEN;
        break;
    default:
        ubifs_err("unsupported key format");
        err = -EINVAL;
        goto out;
    }

    c->leb_cnt       = le32_to_cpu(sup->leb_cnt);
    c->max_leb_cnt   = le32_to_cpu(sup->max_leb_cnt);
    c->max_bud_bytes = le64_to_cpu(sup->max_bud_bytes);
    c->log_lebs      = le32_to_cpu(sup->log_lebs);
    c->lpt_lebs      = le32_to_cpu(sup->lpt_lebs);
    c->orph_lebs     = le32_to_cpu(sup->orph_lebs);
    c->jhead_cnt     = le32_to_cpu(sup->jhead_cnt) + NONDATA_JHEADS_CNT;
    c->fanout        = le32_to_cpu(sup->fanout);
    c->lsave_cnt     = le32_to_cpu(sup->lsave_cnt);
    c->rp_size       = le64_to_cpu(sup->rp_size);
    c->rp_uid        = make_kuid(&init_user_ns, le32_to_cpu(sup->rp_uid));
    c->rp_gid        = make_kgid(&init_user_ns, le32_to_cpu(sup->rp_gid));
    sup_flags        = le32_to_cpu(sup->flags);
    if (!c->mount_opts.override_compr)
        c->default_compr = le16_to_cpu(sup->default_compr);

    c->vfs_sb->s_time_gran = le32_to_cpu(sup->time_gran);
    memcpy(&c->uuid, &sup->uuid, 16);
    c->big_lpt = !!(sup_flags & UBIFS_FLG_BIGLPT);
    c->space_fixup = !!(sup_flags & UBIFS_FLG_SPACE_FIXUP);

    /* Automatically increase file system size to the maximum size */
    c->old_leb_cnt = c->leb_cnt;
    if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
        c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
        if (c->ro_mount)
            dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
                c->old_leb_cnt, c->leb_cnt);
        else {
            dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
                c->old_leb_cnt, c->leb_cnt);
            sup->leb_cnt = cpu_to_le32(c->leb_cnt);
            err = ubifs_write_sb_node(c, sup);
            if (err)
                goto out;
            c->old_leb_cnt = c->leb_cnt;
        }
    }

    c->log_bytes = (long long)c->log_lebs * c->leb_size;
    c->log_last = UBIFS_LOG_LNUM + c->log_lebs - 1;
    c->lpt_first = UBIFS_LOG_LNUM + c->log_lebs;
    c->lpt_last = c->lpt_first + c->lpt_lebs - 1;
    c->orph_first = c->lpt_last + 1;
    c->orph_last = c->orph_first + c->orph_lebs - 1;
    c->main_lebs = c->leb_cnt - UBIFS_SB_LEBS - UBIFS_MST_LEBS;
    c->main_lebs -= c->log_lebs + c->lpt_lebs + c->orph_lebs;
    c->main_first = c->leb_cnt - c->main_lebs;

    err = validate_sb(c, sup);
out:
    kfree(sup);
    return err;
}

static int fixup_leb(struct ubifs_info *c, int lnum, int len)
{
    int err;

    ubifs_assert(len >= 0);
    ubifs_assert(len % c->min_io_size == 0);
    ubifs_assert(len < c->leb_size);

    if (len == 0) {
        dbg_mnt("unmap empty LEB %d", lnum);
        return ubifs_leb_unmap(c, lnum);
    }

    dbg_mnt("fixup LEB %d, data len %d", lnum, len);
    err = ubifs_leb_read(c, lnum, c->sbuf, 0, len, 1);
    if (err)
        return err;

    return ubifs_leb_change(c, lnum, c->sbuf, len);
}

static int fixup_free_space(struct ubifs_info *c)
{
    int lnum, err = 0;
    struct ubifs_lprops *lprops;

    ubifs_get_lprops(c);

    /* Fixup LEBs in the master area */
    for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {
        err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);
        if (err)
            goto out;
    }

    /* Unmap unused log LEBs */
    lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
    while (lnum != c->ltail_lnum) {
        err = fixup_leb(c, lnum, 0);
        if (err)
            goto out;
        lnum = ubifs_next_log_lnum(c, lnum);
    }

    /*
     * Fixup the log head which contains the only a CS node at the
     * beginning.
     */
    err = fixup_leb(c, c->lhead_lnum,
            ALIGN(UBIFS_CS_NODE_SZ, c->min_io_size));
    if (err)
        goto out;

    /* Fixup LEBs in the LPT area */
    for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {
        int free = c->ltab[lnum - c->lpt_first].free;

        if (free > 0) {
            err = fixup_leb(c, lnum, c->leb_size - free);
            if (err)
                goto out;
        }
    }

    /* Unmap LEBs in the orphans area */
    for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {
        err = fixup_leb(c, lnum, 0);
        if (err)
            goto out;
    }

    /* Fixup LEBs in the main area */
    for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {
        lprops = ubifs_lpt_lookup(c, lnum);
        if (IS_ERR(lprops)) {
            err = PTR_ERR(lprops);
            goto out;
        }

        if (lprops->free > 0) {
            err = fixup_leb(c, lnum, c->leb_size - lprops->free);
            if (err)
                goto out;
        }
    }

out:
    ubifs_release_lprops(c);
    return err;
}

int ubifs_fixup_free_space(struct ubifs_info *c)
{
    int err;
    struct ubifs_sb_node *sup;

    ubifs_assert(c->space_fixup);
    ubifs_assert(!c->ro_mount);

    ubifs_msg("start fixing up free space");

    err = fixup_free_space(c);
    if (err)
        return err;

    sup = ubifs_read_sb_node(c);
    if (IS_ERR(sup))
        return PTR_ERR(sup);

    /* Free-space fixup is no longer required */
    c->space_fixup = 0;
    sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);

    err = ubifs_write_sb_node(c, sup);
    kfree(sup);
    if (err)
        return err;

    ubifs_msg("free space fixup complete");
    return err;
}