super.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 initialization and VFS superblock operations. Some
 * initialization stuff which is rather large and complex is placed at
 * corresponding subsystems, but most of it is here.
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/kthread.h>
#include <linux/parser.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/math64.h>
#include <linux/writeback.h>
#include "ubifs.h"

/*
 * Maximum amount of memory we may 'kmalloc()' without worrying that we are
 * allocating too much.
 */
#define UBIFS_KMALLOC_OK (128*1024)

/* Slab cache for UBIFS inodes */
struct kmem_cache *ubifs_inode_slab;

/* UBIFS TNC shrinker description */
static struct shrinker ubifs_shrinker_info = {
    .shrink = ubifs_shrinker,
    .seeks = DEFAULT_SEEKS,
};

static int validate_inode(struct ubifs_info *c, const struct inode *inode)
{
    int err;
    const struct ubifs_inode *ui = ubifs_inode(inode);

    if (inode->i_size > c->max_inode_sz) {
        ubifs_err("inode is too large (%lld)",
              (long long)inode->i_size);
        return 1;
    }

    if (ui->compr_type < 0 || ui->compr_type >= UBIFS_COMPR_TYPES_CNT) {
        ubifs_err("unknown compression type %d", ui->compr_type);
        return 2;
    }

    if (ui->xattr_names + ui->xattr_cnt > XATTR_LIST_MAX)
        return 3;

    if (ui->data_len < 0 || ui->data_len > UBIFS_MAX_INO_DATA)
        return 4;

    if (ui->xattr && !S_ISREG(inode->i_mode))
        return 5;

    if (!ubifs_compr_present(ui->compr_type)) {
        ubifs_warn("inode %lu uses '%s' compression, but it was not compiled in",
               inode->i_ino, ubifs_compr_name(ui->compr_type));
    }

    err = dbg_check_dir(c, inode);
    return err;
}

struct inode *ubifs_iget(struct super_block *sb, unsigned long inum)
{
    int err;
    union ubifs_key key;
    struct ubifs_ino_node *ino;
    struct ubifs_info *c = sb->s_fs_info;
    struct inode *inode;
    struct ubifs_inode *ui;

    dbg_gen("inode %lu", inum);

    inode = iget_locked(sb, inum);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    if (!(inode->i_state & I_NEW))
        return inode;
    ui = ubifs_inode(inode);

    ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
    if (!ino) {
        err = -ENOMEM;
        goto out;
    }

    ino_key_init(c, &key, inode->i_ino);

    err = ubifs_tnc_lookup(c, &key, ino);
    if (err)
        goto out_ino;

    inode->i_flags |= (S_NOCMTIME | S_NOATIME);
    set_nlink(inode, le32_to_cpu(ino->nlink));
    i_uid_write(inode, le32_to_cpu(ino->uid));
    i_gid_write(inode, le32_to_cpu(ino->gid));
    inode->i_atime.tv_sec  = (int64_t)le64_to_cpu(ino->atime_sec);
    inode->i_atime.tv_nsec = le32_to_cpu(ino->atime_nsec);
    inode->i_mtime.tv_sec  = (int64_t)le64_to_cpu(ino->mtime_sec);
    inode->i_mtime.tv_nsec = le32_to_cpu(ino->mtime_nsec);
    inode->i_ctime.tv_sec  = (int64_t)le64_to_cpu(ino->ctime_sec);
    inode->i_ctime.tv_nsec = le32_to_cpu(ino->ctime_nsec);
    inode->i_mode = le32_to_cpu(ino->mode);
    inode->i_size = le64_to_cpu(ino->size);

    ui->data_len    = le32_to_cpu(ino->data_len);
    ui->flags       = le32_to_cpu(ino->flags);
    ui->compr_type  = le16_to_cpu(ino->compr_type);
    ui->creat_sqnum = le64_to_cpu(ino->creat_sqnum);
    ui->xattr_cnt   = le32_to_cpu(ino->xattr_cnt);
    ui->xattr_size  = le32_to_cpu(ino->xattr_size);
    ui->xattr_names = le32_to_cpu(ino->xattr_names);
    ui->synced_i_size = ui->ui_size = inode->i_size;

    ui->xattr = (ui->flags & UBIFS_XATTR_FL) ? 1 : 0;

    err = validate_inode(c, inode);
    if (err)
        goto out_invalid;

    /* Disable read-ahead */
    inode->i_mapping->backing_dev_info = &c->bdi;

    switch (inode->i_mode & S_IFMT) {
    case S_IFREG:
        inode->i_mapping->a_ops = &ubifs_file_address_operations;
        inode->i_op = &ubifs_file_inode_operations;
        inode->i_fop = &ubifs_file_operations;
        if (ui->xattr) {
            ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
            if (!ui->data) {
                err = -ENOMEM;
                goto out_ino;
            }
            memcpy(ui->data, ino->data, ui->data_len);
            ((char *)ui->data)[ui->data_len] = '\0';
        } else if (ui->data_len != 0) {
            err = 10;
            goto out_invalid;
        }
        break;
    case S_IFDIR:
        inode->i_op  = &ubifs_dir_inode_operations;
        inode->i_fop = &ubifs_dir_operations;
        if (ui->data_len != 0) {
            err = 11;
            goto out_invalid;
        }
        break;
    case S_IFLNK:
        inode->i_op = &ubifs_symlink_inode_operations;
        if (ui->data_len <= 0 || ui->data_len > UBIFS_MAX_INO_DATA) {
            err = 12;
            goto out_invalid;
        }
        ui->data = kmalloc(ui->data_len + 1, GFP_NOFS);
        if (!ui->data) {
            err = -ENOMEM;
            goto out_ino;
        }
        memcpy(ui->data, ino->data, ui->data_len);
        ((char *)ui->data)[ui->data_len] = '\0';
        break;
    case S_IFBLK:
    case S_IFCHR:
    {
        dev_t rdev;
        union ubifs_dev_desc *dev;

        ui->data = kmalloc(sizeof(union ubifs_dev_desc), GFP_NOFS);
        if (!ui->data) {
            err = -ENOMEM;
            goto out_ino;
        }

        dev = (union ubifs_dev_desc *)ino->data;
        if (ui->data_len == sizeof(dev->new))
            rdev = new_decode_dev(le32_to_cpu(dev->new));
        else if (ui->data_len == sizeof(dev->huge))
            rdev = huge_decode_dev(le64_to_cpu(dev->huge));
        else {
            err = 13;
            goto out_invalid;
        }
        memcpy(ui->data, ino->data, ui->data_len);
        inode->i_op = &ubifs_file_inode_operations;
        init_special_inode(inode, inode->i_mode, rdev);
        break;
    }
    case S_IFSOCK:
    case S_IFIFO:
        inode->i_op = &ubifs_file_inode_operations;
        init_special_inode(inode, inode->i_mode, 0);
        if (ui->data_len != 0) {
            err = 14;
            goto out_invalid;
        }
        break;
    default:
        err = 15;
        goto out_invalid;
    }

    kfree(ino);
    ubifs_set_inode_flags(inode);
    unlock_new_inode(inode);
    return inode;

out_invalid:
    ubifs_err("inode %lu validation failed, error %d", inode->i_ino, err);
    ubifs_dump_node(c, ino);
    ubifs_dump_inode(c, inode);
    err = -EINVAL;
out_ino:
    kfree(ino);
out:
    ubifs_err("failed to read inode %lu, error %d", inode->i_ino, err);
    iget_failed(inode);
    return ERR_PTR(err);
}

static struct inode *ubifs_alloc_inode(struct super_block *sb)
{
    struct ubifs_inode *ui;

    ui = kmem_cache_alloc(ubifs_inode_slab, GFP_NOFS);
    if (!ui)
        return NULL;

    memset((void *)ui + sizeof(struct inode), 0,
           sizeof(struct ubifs_inode) - sizeof(struct inode));
    mutex_init(&ui->ui_mutex);
    spin_lock_init(&ui->ui_lock);
    return &ui->vfs_inode;
};

static void ubifs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    struct ubifs_inode *ui = ubifs_inode(inode);
    kmem_cache_free(ubifs_inode_slab, ui);
}

static void ubifs_destroy_inode(struct inode *inode)
{
    struct ubifs_inode *ui = ubifs_inode(inode);

    kfree(ui->data);
    call_rcu(&inode->i_rcu, ubifs_i_callback);
}

/*
 * Note, Linux write-back code calls this without 'i_mutex'.
 */
static int ubifs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
    int err = 0;
    struct ubifs_info *c = inode->i_sb->s_fs_info;
    struct ubifs_inode *ui = ubifs_inode(inode);

    ubifs_assert(!ui->xattr);
    if (is_bad_inode(inode))
        return 0;

    mutex_lock(&ui->ui_mutex);
    /*
     * Due to races between write-back forced by budgeting
     * (see 'sync_some_inodes()') and background write-back, the inode may
     * have already been synchronized, do not do this again. This might
     * also happen if it was synchronized in an VFS operation, e.g.
     * 'ubifs_link()'.
     */
    if (!ui->dirty) {
        mutex_unlock(&ui->ui_mutex);
        return 0;
    }

    /*
     * As an optimization, do not write orphan inodes to the media just
     * because this is not needed.
     */
    dbg_gen("inode %lu, mode %#x, nlink %u",
        inode->i_ino, (int)inode->i_mode, inode->i_nlink);
    if (inode->i_nlink) {
        err = ubifs_jnl_write_inode(c, inode);
        if (err)
            ubifs_err("can't write inode %lu, error %d",
                  inode->i_ino, err);
        else
            err = dbg_check_inode_size(c, inode, ui->ui_size);
    }

    ui->dirty = 0;
    mutex_unlock(&ui->ui_mutex);
    ubifs_release_dirty_inode_budget(c, ui);
    return err;
}

static void ubifs_evict_inode(struct inode *inode)
{
    int err;
    struct ubifs_info *c = inode->i_sb->s_fs_info;
    struct ubifs_inode *ui = ubifs_inode(inode);

    if (ui->xattr)
        /*
         * Extended attribute inode deletions are fully handled in
         * 'ubifs_removexattr()'. These inodes are special and have
         * limited usage, so there is nothing to do here.
         */
        goto out;

    dbg_gen("inode %lu, mode %#x", inode->i_ino, (int)inode->i_mode);
    ubifs_assert(!atomic_read(&inode->i_count));

    truncate_inode_pages(&inode->i_data, 0);

    if (inode->i_nlink)
        goto done;

    if (is_bad_inode(inode))
        goto out;

    ui->ui_size = inode->i_size = 0;
    err = ubifs_jnl_delete_inode(c, inode);
    if (err)
        /*
         * Worst case we have a lost orphan inode wasting space, so a
         * simple error message is OK here.
         */
        ubifs_err("can't delete inode %lu, error %d",
              inode->i_ino, err);

out:
    if (ui->dirty)
        ubifs_release_dirty_inode_budget(c, ui);
    else {
        /* We've deleted something - clean the "no space" flags */
        c->bi.nospace = c->bi.nospace_rp = 0;
        smp_wmb();
    }
done:
    clear_inode(inode);
}

static void ubifs_dirty_inode(struct inode *inode, int flags)
{
    struct ubifs_inode *ui = ubifs_inode(inode);

    ubifs_assert(mutex_is_locked(&ui->ui_mutex));
    if (!ui->dirty) {
        ui->dirty = 1;
        dbg_gen("inode %lu",  inode->i_ino);
    }
}

static int ubifs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct ubifs_info *c = dentry->d_sb->s_fs_info;
    unsigned long long free;
    __le32 *uuid = (__le32 *)c->uuid;

    free = ubifs_get_free_space(c);
    dbg_gen("free space %lld bytes (%lld blocks)",
        free, free >> UBIFS_BLOCK_SHIFT);

    buf->f_type = UBIFS_SUPER_MAGIC;
    buf->f_bsize = UBIFS_BLOCK_SIZE;
    buf->f_blocks = c->block_cnt;
    buf->f_bfree = free >> UBIFS_BLOCK_SHIFT;
    if (free > c->report_rp_size)
        buf->f_bavail = (free - c->report_rp_size) >> UBIFS_BLOCK_SHIFT;
    else
        buf->f_bavail = 0;
    buf->f_files = 0;
    buf->f_ffree = 0;
    buf->f_namelen = UBIFS_MAX_NLEN;
    buf->f_fsid.val[0] = le32_to_cpu(uuid[0]) ^ le32_to_cpu(uuid[2]);
    buf->f_fsid.val[1] = le32_to_cpu(uuid[1]) ^ le32_to_cpu(uuid[3]);
    ubifs_assert(buf->f_bfree <= c->block_cnt);
    return 0;
}

static int ubifs_show_options(struct seq_file *s, struct dentry *root)
{
    struct ubifs_info *c = root->d_sb->s_fs_info;

    if (c->mount_opts.unmount_mode == 2)
        seq_printf(s, ",fast_unmount");
    else if (c->mount_opts.unmount_mode == 1)
        seq_printf(s, ",norm_unmount");

    if (c->mount_opts.bulk_read == 2)
        seq_printf(s, ",bulk_read");
    else if (c->mount_opts.bulk_read == 1)
        seq_printf(s, ",no_bulk_read");

    if (c->mount_opts.chk_data_crc == 2)
        seq_printf(s, ",chk_data_crc");
    else if (c->mount_opts.chk_data_crc == 1)
        seq_printf(s, ",no_chk_data_crc");

    if (c->mount_opts.override_compr) {
        seq_printf(s, ",compr=%s",
               ubifs_compr_name(c->mount_opts.compr_type));
    }

    return 0;
}

static int ubifs_sync_fs(struct super_block *sb, int wait)
{
    int i, err;
    struct ubifs_info *c = sb->s_fs_info;

    /*
     * Zero @wait is just an advisory thing to help the file system shove
     * lots of data into the queues, and there will be the second
     * '->sync_fs()' call, with non-zero @wait.
     */
    if (!wait)
        return 0;

    /*
     * Synchronize write buffers, because 'ubifs_run_commit()' does not
     * do this if it waits for an already running commit.
     */
    for (i = 0; i < c->jhead_cnt; i++) {
        err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
        if (err)
            return err;
    }

    /*
     * Strictly speaking, it is not necessary to commit the journal here,
     * synchronizing write-buffers would be enough. But committing makes
     * UBIFS free space predictions much more accurate, so we want to let
     * the user be able to get more accurate results of 'statfs()' after
     * they synchronize the file system.
     */
    err = ubifs_run_commit(c);
    if (err)
        return err;

    return ubi_sync(c->vi.ubi_num);
}

static int init_constants_early(struct ubifs_info *c)
{
    if (c->vi.corrupted) {
        ubifs_warn("UBI volume is corrupted - read-only mode");
        c->ro_media = 1;
    }

    if (c->di.ro_mode) {
        ubifs_msg("read-only UBI device");
        c->ro_media = 1;
    }

    if (c->vi.vol_type == UBI_STATIC_VOLUME) {
        ubifs_msg("static UBI volume - read-only mode");
        c->ro_media = 1;
    }

    c->leb_cnt = c->vi.size;
    c->leb_size = c->vi.usable_leb_size;
    c->leb_start = c->di.leb_start;
    c->half_leb_size = c->leb_size / 2;
    c->min_io_size = c->di.min_io_size;
    c->min_io_shift = fls(c->min_io_size) - 1;
    c->max_write_size = c->di.max_write_size;
    c->max_write_shift = fls(c->max_write_size) - 1;

    if (c->leb_size < UBIFS_MIN_LEB_SZ) {
        ubifs_err("too small LEBs (%d bytes), min. is %d bytes",
              c->leb_size, UBIFS_MIN_LEB_SZ);
        return -EINVAL;
    }

    if (c->leb_cnt < UBIFS_MIN_LEB_CNT) {
        ubifs_err("too few LEBs (%d), min. is %d",
              c->leb_cnt, UBIFS_MIN_LEB_CNT);
        return -EINVAL;
    }

    if (!is_power_of_2(c->min_io_size)) {
        ubifs_err("bad min. I/O size %d", c->min_io_size);
        return -EINVAL;
    }

    /*
     * Maximum write size has to be greater or equivalent to min. I/O
     * size, and be multiple of min. I/O size.
     */
    if (c->max_write_size < c->min_io_size ||
        c->max_write_size % c->min_io_size ||
        !is_power_of_2(c->max_write_size)) {
        ubifs_err("bad write buffer size %d for %d min. I/O unit",
              c->max_write_size, c->min_io_size);
        return -EINVAL;
    }

    /*
     * UBIFS aligns all node to 8-byte boundary, so to make function in
     * io.c simpler, assume minimum I/O unit size to be 8 bytes if it is
     * less than 8.
     */
    if (c->min_io_size < 8) {
        c->min_io_size = 8;
        c->min_io_shift = 3;
        if (c->max_write_size < c->min_io_size) {
            c->max_write_size = c->min_io_size;
            c->max_write_shift = c->min_io_shift;
        }
    }

    c->ref_node_alsz = ALIGN(UBIFS_REF_NODE_SZ, c->min_io_size);
    c->mst_node_alsz = ALIGN(UBIFS_MST_NODE_SZ, c->min_io_size);

    /*
     * Initialize node length ranges which are mostly needed for node
     * length validation.
     */
    c->ranges[UBIFS_PAD_NODE].len  = UBIFS_PAD_NODE_SZ;
    c->ranges[UBIFS_SB_NODE].len   = UBIFS_SB_NODE_SZ;
    c->ranges[UBIFS_MST_NODE].len  = UBIFS_MST_NODE_SZ;
    c->ranges[UBIFS_REF_NODE].len  = UBIFS_REF_NODE_SZ;
    c->ranges[UBIFS_TRUN_NODE].len = UBIFS_TRUN_NODE_SZ;
    c->ranges[UBIFS_CS_NODE].len   = UBIFS_CS_NODE_SZ;

    c->ranges[UBIFS_INO_NODE].min_len  = UBIFS_INO_NODE_SZ;
    c->ranges[UBIFS_INO_NODE].max_len  = UBIFS_MAX_INO_NODE_SZ;
    c->ranges[UBIFS_ORPH_NODE].min_len =
                UBIFS_ORPH_NODE_SZ + sizeof(__le64);
    c->ranges[UBIFS_ORPH_NODE].max_len = c->leb_size;
    c->ranges[UBIFS_DENT_NODE].min_len = UBIFS_DENT_NODE_SZ;
    c->ranges[UBIFS_DENT_NODE].max_len = UBIFS_MAX_DENT_NODE_SZ;
    c->ranges[UBIFS_XENT_NODE].min_len = UBIFS_XENT_NODE_SZ;
    c->ranges[UBIFS_XENT_NODE].max_len = UBIFS_MAX_XENT_NODE_SZ;
    c->ranges[UBIFS_DATA_NODE].min_len = UBIFS_DATA_NODE_SZ;
    c->ranges[UBIFS_DATA_NODE].max_len = UBIFS_MAX_DATA_NODE_SZ;
    /*
     * Minimum indexing node size is amended later when superblock is
     * read and the key length is known.
     */
    c->ranges[UBIFS_IDX_NODE].min_len = UBIFS_IDX_NODE_SZ + UBIFS_BRANCH_SZ;
    /*
     * Maximum indexing node size is amended later when superblock is
     * read and the fanout is known.
     */
    c->ranges[UBIFS_IDX_NODE].max_len = INT_MAX;

    /*
     * Initialize dead and dark LEB space watermarks. See gc.c for comments
     * about these values.
     */
    c->dead_wm = ALIGN(MIN_WRITE_SZ, c->min_io_size);
    c->dark_wm = ALIGN(UBIFS_MAX_NODE_SZ, c->min_io_size);

    /*
     * Calculate how many bytes would be wasted at the end of LEB if it was
     * fully filled with data nodes of maximum size. This is used in
     * calculations when reporting free space.
     */
    c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;

    /* Buffer size for bulk-reads */
    c->max_bu_buf_len = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
    if (c->max_bu_buf_len > c->leb_size)
        c->max_bu_buf_len = c->leb_size;
    return 0;
}

static int bud_wbuf_callback(struct ubifs_info *c, int lnum, int free, int pad)
{
    return ubifs_update_one_lp(c, lnum, free, pad, 0, 0);
}

/*
 * init_constants_sb - initialize UBIFS constants.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which initializes various UBIFS constants after
 * the superblock has been read. It also checks various UBIFS parameters and
 * makes sure they are all right. Returns zero in case of success and a
 * negative error code in case of failure.
 */
static int init_constants_sb(struct ubifs_info *c)
{
    int tmp, err;
    long long tmp64;

    c->main_bytes = (long long)c->main_lebs * c->leb_size;
    c->max_znode_sz = sizeof(struct ubifs_znode) +
                c->fanout * sizeof(struct ubifs_zbranch);

    tmp = ubifs_idx_node_sz(c, 1);
    c->ranges[UBIFS_IDX_NODE].min_len = tmp;
    c->min_idx_node_sz = ALIGN(tmp, 8);

    tmp = ubifs_idx_node_sz(c, c->fanout);
    c->ranges[UBIFS_IDX_NODE].max_len = tmp;
    c->max_idx_node_sz = ALIGN(tmp, 8);

    /* Make sure LEB size is large enough to fit full commit */
    tmp = UBIFS_CS_NODE_SZ + UBIFS_REF_NODE_SZ * c->jhead_cnt;
    tmp = ALIGN(tmp, c->min_io_size);
    if (tmp > c->leb_size) {
        ubifs_err("too small LEB size %d, at least %d needed",
              c->leb_size, tmp);
        return -EINVAL;
    }

    /*
     * Make sure that the log is large enough to fit reference nodes for
     * all buds plus one reserved LEB.
     */
    tmp64 = c->max_bud_bytes + c->leb_size - 1;
    c->max_bud_cnt = div_u64(tmp64, c->leb_size);
    tmp = (c->ref_node_alsz * c->max_bud_cnt + c->leb_size - 1);
    tmp /= c->leb_size;
    tmp += 1;
    if (c->log_lebs < tmp) {
        ubifs_err("too small log %d LEBs, required min. %d LEBs",
              c->log_lebs, tmp);
        return -EINVAL;
    }

    /*
     * When budgeting we assume worst-case scenarios when the pages are not
     * be compressed and direntries are of the maximum size.
     *
     * Note, data, which may be stored in inodes is budgeted separately, so
     * it is not included into 'c->bi.inode_budget'.
     */
    c->bi.page_budget = UBIFS_MAX_DATA_NODE_SZ * UBIFS_BLOCKS_PER_PAGE;
    c->bi.inode_budget = UBIFS_INO_NODE_SZ;
    c->bi.dent_budget = UBIFS_MAX_DENT_NODE_SZ;

    /*
     * When the amount of flash space used by buds becomes
     * 'c->max_bud_bytes', UBIFS just blocks all writers and starts commit.
     * The writers are unblocked when the commit is finished. To avoid
     * writers to be blocked UBIFS initiates background commit in advance,
     * when number of bud bytes becomes above the limit defined below.
     */
    c->bg_bud_bytes = (c->max_bud_bytes * 13) >> 4;

    /*
     * Ensure minimum journal size. All the bytes in the journal heads are
     * considered to be used, when calculating the current journal usage.
     * Consequently, if the journal is too small, UBIFS will treat it as
     * always full.
     */
    tmp64 = (long long)(c->jhead_cnt + 1) * c->leb_size + 1;
    if (c->bg_bud_bytes < tmp64)
        c->bg_bud_bytes = tmp64;
    if (c->max_bud_bytes < tmp64 + c->leb_size)
        c->max_bud_bytes = tmp64 + c->leb_size;

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

    /* Initialize effective LEB size used in budgeting calculations */
    c->idx_leb_size = c->leb_size - c->max_idx_node_sz;
    return 0;
}

/*
 * init_constants_master - initialize UBIFS constants.
 * @c: UBIFS file-system description object
 *
 * This is a helper function which initializes various UBIFS constants after
 * the master node has been read. It also checks various UBIFS parameters and
 * makes sure they are all right.
 */
static void init_constants_master(struct ubifs_info *c)
{
    long long tmp64;

    c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);
    c->report_rp_size = ubifs_reported_space(c, c->rp_size);

    /*
     * Calculate total amount of FS blocks. This number is not used
     * internally because it does not make much sense for UBIFS, but it is
     * necessary to report something for the 'statfs()' call.
     *
     * Subtract the LEB reserved for GC, the LEB which is reserved for
     * deletions, minimum LEBs for the index, and assume only one journal
     * head is available.
     */
    tmp64 = c->main_lebs - 1 - 1 - MIN_INDEX_LEBS - c->jhead_cnt + 1;
    tmp64 *= (long long)c->leb_size - c->leb_overhead;
    tmp64 = ubifs_reported_space(c, tmp64);
    c->block_cnt = tmp64 >> UBIFS_BLOCK_SHIFT;
}

static int take_gc_lnum(struct ubifs_info *c)
{
    int err;

    if (c->gc_lnum == -1) {
        ubifs_err("no LEB for GC");
        return -EINVAL;
    }

    /* And we have to tell lprops that this LEB is taken */
    err = ubifs_change_one_lp(c, c->gc_lnum, c->leb_size, 0,
                  LPROPS_TAKEN, 0, 0);
    return err;
}

static int alloc_wbufs(struct ubifs_info *c)
{
    int i, err;

    c->jheads = kzalloc(c->jhead_cnt * sizeof(struct ubifs_jhead),
               GFP_KERNEL);
    if (!c->jheads)
        return -ENOMEM;

    /* Initialize journal heads */
    for (i = 0; i < c->jhead_cnt; i++) {
        INIT_LIST_HEAD(&c->jheads[i].buds_list);
        err = ubifs_wbuf_init(c, &c->jheads[i].wbuf);
        if (err)
            return err;

        c->jheads[i].wbuf.sync_callback = &bud_wbuf_callback;
        c->jheads[i].wbuf.jhead = i;
        c->jheads[i].grouped = 1;
    }

    /*
     * Garbage Collector head does not need to be synchronized by timer.
     * Also GC head nodes are not grouped.
     */
    c->jheads[GCHD].wbuf.no_timer = 1;
    c->jheads[GCHD].grouped = 0;

    return 0;
}

static void free_wbufs(struct ubifs_info *c)
{
    int i;

    if (c->jheads) {
        for (i = 0; i < c->jhead_cnt; i++) {
            kfree(c->jheads[i].wbuf.buf);
            kfree(c->jheads[i].wbuf.inodes);
        }
        kfree(c->jheads);
        c->jheads = NULL;
    }
}

static void free_orphans(struct ubifs_info *c)
{
    struct ubifs_orphan *orph;

    while (c->orph_dnext) {
        orph = c->orph_dnext;
        c->orph_dnext = orph->dnext;
        list_del(&orph->list);
        kfree(orph);
    }

    while (!list_empty(&c->orph_list)) {
        orph = list_entry(c->orph_list.next, struct ubifs_orphan, list);
        list_del(&orph->list);
        kfree(orph);
        ubifs_err("orphan list not empty at unmount");
    }

    vfree(c->orph_buf);
    c->orph_buf = NULL;
}

static void free_buds(struct ubifs_info *c)
{
    struct rb_node *this = c->buds.rb_node;
    struct ubifs_bud *bud;

    while (this) {
        if (this->rb_left)
            this = this->rb_left;
        else if (this->rb_right)
            this = this->rb_right;
        else {
            bud = rb_entry(this, struct ubifs_bud, rb);
            this = rb_parent(this);
            if (this) {
                if (this->rb_left == &bud->rb)
                    this->rb_left = NULL;
                else
                    this->rb_right = NULL;
            }
            kfree(bud);
        }
    }
}

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

    c->empty = 1;
    for (lnum = 0; lnum < c->leb_cnt; lnum++) {
        err = ubifs_is_mapped(c, lnum);
        if (unlikely(err < 0))
            return err;
        if (err == 1) {
            c->empty = 0;
            break;
        }

        cond_resched();
    }

    return 0;
}

/*
 * UBIFS mount options.
 *
 * Opt_fast_unmount: do not run a journal commit before un-mounting
 * Opt_norm_unmount: run a journal commit before un-mounting
 * Opt_bulk_read: enable bulk-reads
 * Opt_no_bulk_read: disable bulk-reads
 * Opt_chk_data_crc: check CRCs when reading data nodes
 * Opt_no_chk_data_crc: do not check CRCs when reading data nodes
 * Opt_override_compr: override default compressor
 * Opt_err: just end of array marker
 */
enum {
    Opt_fast_unmount,
    Opt_norm_unmount,
    Opt_bulk_read,
    Opt_no_bulk_read,
    Opt_chk_data_crc,
    Opt_no_chk_data_crc,
    Opt_override_compr,
    Opt_err,
};

static const match_table_t tokens = {
    {Opt_fast_unmount, "fast_unmount"},
    {Opt_norm_unmount, "norm_unmount"},
    {Opt_bulk_read, "bulk_read"},
    {Opt_no_bulk_read, "no_bulk_read"},
    {Opt_chk_data_crc, "chk_data_crc"},
    {Opt_no_chk_data_crc, "no_chk_data_crc"},
    {Opt_override_compr, "compr=%s"},
    {Opt_err, NULL},
};

static int parse_standard_option(const char *option)
{
    ubifs_msg("parse %s", option);
    if (!strcmp(option, "sync"))
        return MS_SYNCHRONOUS;
    return 0;
}

static int ubifs_parse_options(struct ubifs_info *c, char *options,
                   int is_remount)
{
    char *p;
    substring_t args[MAX_OPT_ARGS];

    if (!options)
        return 0;

    while ((p = strsep(&options, ","))) {
        int token;

        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        /*
         * %Opt_fast_unmount and %Opt_norm_unmount options are ignored.
         * We accept them in order to be backward-compatible. But this
         * should be removed at some point.
         */
        case Opt_fast_unmount:
            c->mount_opts.unmount_mode = 2;
            break;
        case Opt_norm_unmount:
            c->mount_opts.unmount_mode = 1;
            break;
        case Opt_bulk_read:
            c->mount_opts.bulk_read = 2;
            c->bulk_read = 1;
            break;
        case Opt_no_bulk_read:
            c->mount_opts.bulk_read = 1;
            c->bulk_read = 0;
            break;
        case Opt_chk_data_crc:
            c->mount_opts.chk_data_crc = 2;
            c->no_chk_data_crc = 0;
            break;
        case Opt_no_chk_data_crc:
            c->mount_opts.chk_data_crc = 1;
            c->no_chk_data_crc = 1;
            break;
        case Opt_override_compr:
        {
            char *name = match_strdup(&args[0]);

            if (!name)
                return -ENOMEM;
            if (!strcmp(name, "none"))
                c->mount_opts.compr_type = UBIFS_COMPR_NONE;
            else if (!strcmp(name, "lzo"))
                c->mount_opts.compr_type = UBIFS_COMPR_LZO;
            else if (!strcmp(name, "zlib"))
                c->mount_opts.compr_type = UBIFS_COMPR_ZLIB;
            else {
                ubifs_err("unknown compressor \"%s\"", name);
                kfree(name);
                return -EINVAL;
            }
            kfree(name);
            c->mount_opts.override_compr = 1;
            c->default_compr = c->mount_opts.compr_type;
            break;
        }
        default:
        {
            unsigned long flag;
            struct super_block *sb = c->vfs_sb;

            flag = parse_standard_option(p);
            if (!flag) {
                ubifs_err("unrecognized mount option \"%s\" or missing value",
                      p);
                return -EINVAL;
            }
            sb->s_flags |= flag;
            break;
        }
        }
    }

    return 0;
}

static void destroy_journal(struct ubifs_info *c)
{
    while (!list_empty(&c->unclean_leb_list)) {
        struct ubifs_unclean_leb *ucleb;

        ucleb = list_entry(c->unclean_leb_list.next,
                   struct ubifs_unclean_leb, list);
        list_del(&ucleb->list);
        kfree(ucleb);
    }
    while (!list_empty(&c->old_buds)) {
        struct ubifs_bud *bud;

        bud = list_entry(c->old_buds.next, struct ubifs_bud, list);
        list_del(&bud->list);
        kfree(bud);
    }
    ubifs_destroy_idx_gc(c);
    ubifs_destroy_size_tree(c);
    ubifs_tnc_close(c);
    free_buds(c);
}

static void bu_init(struct ubifs_info *c)
{
    ubifs_assert(c->bulk_read == 1);

    if (c->bu.buf)
        return; /* Already initialized */

again:
    c->bu.buf = kmalloc(c->max_bu_buf_len, GFP_KERNEL | __GFP_NOWARN);
    if (!c->bu.buf) {
        if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
            c->max_bu_buf_len = UBIFS_KMALLOC_OK;
            goto again;
        }

        /* Just disable bulk-read */
        ubifs_warn("cannot allocate %d bytes of memory for bulk-read, disabling it",
               c->max_bu_buf_len);
        c->mount_opts.bulk_read = 1;
        c->bulk_read = 0;
        return;
    }
}

static int check_free_space(struct ubifs_info *c)
{
    ubifs_assert(c->dark_wm > 0);
    if (c->lst.total_free + c->lst.total_dirty < c->dark_wm) {
        ubifs_err("insufficient free space to mount in R/W mode");
        ubifs_dump_budg(c, &c->bi);
        ubifs_dump_lprops(c);
        return -ENOSPC;
    }
    return 0;
}

static int mount_ubifs(struct ubifs_info *c)
{
    int err;
    long long x, y;
    size_t sz;

    c->ro_mount = !!(c->vfs_sb->s_flags & MS_RDONLY);
    err = init_constants_early(c);
    if (err)
        return err;

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

    err = check_volume_empty(c);
    if (err)
        goto out_free;

    if (c->empty && (c->ro_mount || c->ro_media)) {
        /*
         * This UBI volume is empty, and read-only, or the file system
         * is mounted read-only - we cannot format it.
         */
        ubifs_err("can't format empty UBI volume: read-only %s",
              c->ro_media ? "UBI volume" : "mount");
        err = -EROFS;
        goto out_free;
    }

    if (c->ro_media && !c->ro_mount) {
        ubifs_err("cannot mount read-write - read-only media");
        err = -EROFS;
        goto out_free;
    }

    /*
     * The requirement for the buffer is that it should fit indexing B-tree
     * height amount of integers. We assume the height if the TNC tree will
     * never exceed 64.
     */
    err = -ENOMEM;
    c->bottom_up_buf = kmalloc(BOTTOM_UP_HEIGHT * sizeof(int), GFP_KERNEL);
    if (!c->bottom_up_buf)
        goto out_free;

    c->sbuf = vmalloc(c->leb_size);
    if (!c->sbuf)
        goto out_free;

    if (!c->ro_mount) {
        c->ileb_buf = vmalloc(c->leb_size);
        if (!c->ileb_buf)
            goto out_free;
    }

    if (c->bulk_read == 1)
        bu_init(c);

    if (!c->ro_mount) {
        c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ,
                           GFP_KERNEL);
        if (!c->write_reserve_buf)
            goto out_free;
    }

    c->mounting = 1;

    err = ubifs_read_superblock(c);
    if (err)
        goto out_free;

    /*
     * Make sure the compressor which is set as default in the superblock
     * or overridden by mount options is actually compiled in.
     */
    if (!ubifs_compr_present(c->default_compr)) {
        ubifs_err("'compressor \"%s\" is not compiled in",
              ubifs_compr_name(c->default_compr));
        err = -ENOTSUPP;
        goto out_free;
    }

    err = init_constants_sb(c);
    if (err)
        goto out_free;

    sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
    sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
    c->cbuf = kmalloc(sz, GFP_NOFS);
    if (!c->cbuf) {
        err = -ENOMEM;
        goto out_free;
    }

    err = alloc_wbufs(c);
    if (err)
        goto out_cbuf;

    sprintf(c->bgt_name, BGT_NAME_PATTERN, c->vi.ubi_num, c->vi.vol_id);
    if (!c->ro_mount) {
        /* Create background thread */
        c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);
        if (IS_ERR(c->bgt)) {
            err = PTR_ERR(c->bgt);
            c->bgt = NULL;
            ubifs_err("cannot spawn \"%s\", error %d",
                  c->bgt_name, err);
            goto out_wbufs;
        }
        wake_up_process(c->bgt);
    }

    err = ubifs_read_master(c);
    if (err)
        goto out_master;

    init_constants_master(c);

    if ((c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY)) != 0) {
        ubifs_msg("recovery needed");
        c->need_recovery = 1;
    }

    if (c->need_recovery && !c->ro_mount) {
        err = ubifs_recover_inl_heads(c, c->sbuf);
        if (err)
            goto out_master;
    }

    err = ubifs_lpt_init(c, 1, !c->ro_mount);
    if (err)
        goto out_master;

    if (!c->ro_mount && c->space_fixup) {
        err = ubifs_fixup_free_space(c);
        if (err)
            goto out_lpt;
    }

    if (!c->ro_mount) {
        /*
         * Set the "dirty" flag so that if we reboot uncleanly we
         * will notice this immediately on the next mount.
         */
        c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
        err = ubifs_write_master(c);
        if (err)
            goto out_lpt;
    }

    err = dbg_check_idx_size(c, c->bi.old_idx_sz);
    if (err)
        goto out_lpt;

    err = ubifs_replay_journal(c);
    if (err)
        goto out_journal;

    /* Calculate 'min_idx_lebs' after journal replay */
    c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c);

    err = ubifs_mount_orphans(c, c->need_recovery, c->ro_mount);
    if (err)
        goto out_orphans;

    if (!c->ro_mount) {
        int lnum;

        err = check_free_space(c);
        if (err)
            goto out_orphans;

        /* Check for enough log space */
        lnum = c->lhead_lnum + 1;
        if (lnum >= UBIFS_LOG_LNUM + c->log_lebs)
            lnum = UBIFS_LOG_LNUM;
        if (lnum == c->ltail_lnum) {
            err = ubifs_consolidate_log(c);
            if (err)
                goto out_orphans;
        }

        if (c->need_recovery) {
            err = ubifs_recover_size(c);
            if (err)
                goto out_orphans;
            err = ubifs_rcvry_gc_commit(c);
            if (err)
                goto out_orphans;
        } else {
            err = take_gc_lnum(c);
            if (err)
                goto out_orphans;

            /*
             * GC LEB may contain garbage if there was an unclean
             * reboot, and it should be un-mapped.
             */
            err = ubifs_leb_unmap(c, c->gc_lnum);
            if (err)
                goto out_orphans;
        }

        err = dbg_check_lprops(c);
        if (err)
            goto out_orphans;
    } else if (c->need_recovery) {
        err = ubifs_recover_size(c);
        if (err)
            goto out_orphans;
    } else {
        /*
         * Even if we mount read-only, we have to set space in GC LEB
         * to proper value because this affects UBIFS free space
         * reporting. We do not want to have a situation when
         * re-mounting from R/O to R/W changes amount of free space.
         */
        err = take_gc_lnum(c);
        if (err)
            goto out_orphans;
    }

    spin_lock(&ubifs_infos_lock);
    list_add_tail(&c->infos_list, &ubifs_infos);
    spin_unlock(&ubifs_infos_lock);

    if (c->need_recovery) {
        if (c->ro_mount)
            ubifs_msg("recovery deferred");
        else {
            c->need_recovery = 0;
            ubifs_msg("recovery completed");
            /*
             * GC LEB has to be empty and taken at this point. But
             * the journal head LEBs may also be accounted as
             * "empty taken" if they are empty.
             */
            ubifs_assert(c->lst.taken_empty_lebs > 0);
        }
    } else
        ubifs_assert(c->lst.taken_empty_lebs > 0);

    err = dbg_check_filesystem(c);
    if (err)
        goto out_infos;

    err = dbg_debugfs_init_fs(c);
    if (err)
        goto out_infos;

    c->mounting = 0;

    ubifs_msg("mounted UBI device %d, volume %d, name \"%s\"%s",
          c->vi.ubi_num, c->vi.vol_id, c->vi.name,
          c->ro_mount ? ", R/O mode" : NULL);
    x = (long long)c->main_lebs * c->leb_size;
    y = (long long)c->log_lebs * c->leb_size + c->max_bud_bytes;
    ubifs_msg("LEB size: %d bytes (%d KiB), min./max. I/O unit sizes: %d bytes/%d bytes",
          c->leb_size, c->leb_size >> 10, c->min_io_size,
          c->max_write_size);
    ubifs_msg("FS size: %lld bytes (%lld MiB, %d LEBs), journal size %lld bytes (%lld MiB, %d LEBs)",
          x, x >> 20, c->main_lebs,
          y, y >> 20, c->log_lebs + c->max_bud_cnt);
    ubifs_msg("reserved for root: %llu bytes (%llu KiB)",
          c->report_rp_size, c->report_rp_size >> 10);
    ubifs_msg("media format: w%d/r%d (latest is w%d/r%d), UUID %pUB%s",
          c->fmt_version, c->ro_compat_version,
          UBIFS_FORMAT_VERSION, UBIFS_RO_COMPAT_VERSION, c->uuid,
          c->big_lpt ? ", big LPT model" : ", small LPT model");

    dbg_gen("default compressor:  %s", ubifs_compr_name(c->default_compr));
    dbg_gen("data journal heads:  %d",
        c->jhead_cnt - NONDATA_JHEADS_CNT);
    dbg_gen("log LEBs:            %d (%d - %d)",
        c->log_lebs, UBIFS_LOG_LNUM, c->log_last);
    dbg_gen("LPT area LEBs:       %d (%d - %d)",
        c->lpt_lebs, c->lpt_first, c->lpt_last);
    dbg_gen("orphan area LEBs:    %d (%d - %d)",
        c->orph_lebs, c->orph_first, c->orph_last);
    dbg_gen("main area LEBs:      %d (%d - %d)",
        c->main_lebs, c->main_first, c->leb_cnt - 1);
    dbg_gen("index LEBs:          %d", c->lst.idx_lebs);
    dbg_gen("total index bytes:   %lld (%lld KiB, %lld MiB)",
        c->bi.old_idx_sz, c->bi.old_idx_sz >> 10,
        c->bi.old_idx_sz >> 20);
    dbg_gen("key hash type:       %d", c->key_hash_type);
    dbg_gen("tree fanout:         %d", c->fanout);
    dbg_gen("reserved GC LEB:     %d", c->gc_lnum);
    dbg_gen("max. znode size      %d", c->max_znode_sz);
    dbg_gen("max. index node size %d", c->max_idx_node_sz);
    dbg_gen("node sizes:          data %zu, inode %zu, dentry %zu",
        UBIFS_DATA_NODE_SZ, UBIFS_INO_NODE_SZ, UBIFS_DENT_NODE_SZ);
    dbg_gen("node sizes:          trun %zu, sb %zu, master %zu",
        UBIFS_TRUN_NODE_SZ, UBIFS_SB_NODE_SZ, UBIFS_MST_NODE_SZ);
    dbg_gen("node sizes:          ref %zu, cmt. start %zu, orph %zu",
        UBIFS_REF_NODE_SZ, UBIFS_CS_NODE_SZ, UBIFS_ORPH_NODE_SZ);
    dbg_gen("max. node sizes:     data %zu, inode %zu dentry %zu, idx %d",
        UBIFS_MAX_DATA_NODE_SZ, UBIFS_MAX_INO_NODE_SZ,
        UBIFS_MAX_DENT_NODE_SZ, ubifs_idx_node_sz(c, c->fanout));
    dbg_gen("dead watermark:      %d", c->dead_wm);
    dbg_gen("dark watermark:      %d", c->dark_wm);
    dbg_gen("LEB overhead:        %d", c->leb_overhead);
    x = (long long)c->main_lebs * c->dark_wm;
    dbg_gen("max. dark space:     %lld (%lld KiB, %lld MiB)",
        x, x >> 10, x >> 20);
    dbg_gen("maximum bud bytes:   %lld (%lld KiB, %lld MiB)",
        c->max_bud_bytes, c->max_bud_bytes >> 10,
        c->max_bud_bytes >> 20);
    dbg_gen("BG commit bud bytes: %lld (%lld KiB, %lld MiB)",
        c->bg_bud_bytes, c->bg_bud_bytes >> 10,
        c->bg_bud_bytes >> 20);
    dbg_gen("current bud bytes    %lld (%lld KiB, %lld MiB)",
        c->bud_bytes, c->bud_bytes >> 10, c->bud_bytes >> 20);
    dbg_gen("max. seq. number:    %llu", c->max_sqnum);
    dbg_gen("commit number:       %llu", c->cmt_no);

    return 0;

out_infos:
    spin_lock(&ubifs_infos_lock);
    list_del(&c->infos_list);
    spin_unlock(&ubifs_infos_lock);
out_orphans:
    free_orphans(c);
out_journal:
    destroy_journal(c);
out_lpt:
    ubifs_lpt_free(c, 0);
out_master:
    kfree(c->mst_node);
    kfree(c->rcvrd_mst_node);
    if (c->bgt)
        kthread_stop(c->bgt);
out_wbufs:
    free_wbufs(c);
out_cbuf:
    kfree(c->cbuf);
out_free:
    kfree(c->write_reserve_buf);
    kfree(c->bu.buf);
    vfree(c->ileb_buf);
    vfree(c->sbuf);
    kfree(c->bottom_up_buf);
    ubifs_debugging_exit(c);
    return err;
}

static void ubifs_umount(struct ubifs_info *c)
{
    dbg_gen("un-mounting UBI device %d, volume %d", c->vi.ubi_num,
        c->vi.vol_id);

    dbg_debugfs_exit_fs(c);
    spin_lock(&ubifs_infos_lock);
    list_del(&c->infos_list);
    spin_unlock(&ubifs_infos_lock);

    if (c->bgt)
        kthread_stop(c->bgt);

    destroy_journal(c);
    free_wbufs(c);
    free_orphans(c);
    ubifs_lpt_free(c, 0);

    kfree(c->cbuf);
    kfree(c->rcvrd_mst_node);
    kfree(c->mst_node);
    kfree(c->write_reserve_buf);
    kfree(c->bu.buf);
    vfree(c->ileb_buf);
    vfree(c->sbuf);
    kfree(c->bottom_up_buf);
    ubifs_debugging_exit(c);
}

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

    if (c->rw_incompat) {
        ubifs_err("the file-system is not R/W-compatible");
        ubifs_msg("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);
        return -EROFS;
    }

    mutex_lock(&c->umount_mutex);
    dbg_save_space_info(c);
    c->remounting_rw = 1;
    c->ro_mount = 0;

    err = check_free_space(c);
    if (err)
        goto out;

    if (c->old_leb_cnt != c->leb_cnt) {
        struct ubifs_sb_node *sup;

        sup = ubifs_read_sb_node(c);
        if (IS_ERR(sup)) {
            err = PTR_ERR(sup);
            goto out;
        }
        sup->leb_cnt = cpu_to_le32(c->leb_cnt);
        err = ubifs_write_sb_node(c, sup);
        kfree(sup);
        if (err)
            goto out;
    }

    if (c->need_recovery) {
        ubifs_msg("completing deferred recovery");
        err = ubifs_write_rcvrd_mst_node(c);
        if (err)
            goto out;
        err = ubifs_recover_size(c);
        if (err)
            goto out;
        err = ubifs_clean_lebs(c, c->sbuf);
        if (err)
            goto out;
        err = ubifs_recover_inl_heads(c, c->sbuf);
        if (err)
            goto out;
    } else {
        /* A readonly mount is not allowed to have orphans */
        ubifs_assert(c->tot_orphans == 0);
        err = ubifs_clear_orphans(c);
        if (err)
            goto out;
    }

    if (!(c->mst_node->flags & cpu_to_le32(UBIFS_MST_DIRTY))) {
        c->mst_node->flags |= cpu_to_le32(UBIFS_MST_DIRTY);
        err = ubifs_write_master(c);
        if (err)
            goto out;
    }

    c->ileb_buf = vmalloc(c->leb_size);
    if (!c->ileb_buf) {
        err = -ENOMEM;
        goto out;
    }

    c->write_reserve_buf = kmalloc(COMPRESSED_DATA_NODE_BUF_SZ, GFP_KERNEL);
    if (!c->write_reserve_buf)
        goto out;

    err = ubifs_lpt_init(c, 0, 1);
    if (err)
        goto out;

    /* Create background thread */
    c->bgt = kthread_create(ubifs_bg_thread, c, "%s", c->bgt_name);
    if (IS_ERR(c->bgt)) {
        err = PTR_ERR(c->bgt);
        c->bgt = NULL;
        ubifs_err("cannot spawn \"%s\", error %d",
              c->bgt_name, err);
        goto out;
    }
    wake_up_process(c->bgt);

    c->orph_buf = vmalloc(c->leb_size);
    if (!c->orph_buf) {
        err = -ENOMEM;
        goto out;
    }

    /* Check for enough log space */
    lnum = c->lhead_lnum + 1;
    if (lnum >= UBIFS_LOG_LNUM + c->log_lebs)
        lnum = UBIFS_LOG_LNUM;
    if (lnum == c->ltail_lnum) {
        err = ubifs_consolidate_log(c);
        if (err)
            goto out;
    }

    if (c->need_recovery)
        err = ubifs_rcvry_gc_commit(c);
    else
        err = ubifs_leb_unmap(c, c->gc_lnum);
    if (err)
        goto out;

    dbg_gen("re-mounted read-write");
    c->remounting_rw = 0;

    if (c->need_recovery) {
        c->need_recovery = 0;
        ubifs_msg("deferred recovery completed");
    } else {
        /*
         * Do not run the debugging space check if the were doing
         * recovery, because when we saved the information we had the
         * file-system in a state where the TNC and lprops has been
         * modified in memory, but all the I/O operations (including a
         * commit) were deferred. So the file-system was in
         * "non-committed" state. Now the file-system is in committed
         * state, and of course the amount of free space will change
         * because, for example, the old index size was imprecise.
         */
        err = dbg_check_space_info(c);
    }

    if (c->space_fixup) {
        err = ubifs_fixup_free_space(c);
        if (err)
            goto out;
    }

    mutex_unlock(&c->umount_mutex);
    return err;

out:
    c->ro_mount = 1;
    vfree(c->orph_buf);
    c->orph_buf = NULL;
    if (c->bgt) {
        kthread_stop(c->bgt);
        c->bgt = NULL;
    }
    free_wbufs(c);
    kfree(c->write_reserve_buf);
    c->write_reserve_buf = NULL;
    vfree(c->ileb_buf);
    c->ileb_buf = NULL;
    ubifs_lpt_free(c, 1);
    c->remounting_rw = 0;
    mutex_unlock(&c->umount_mutex);
    return err;
}

static void ubifs_remount_ro(struct ubifs_info *c)
{
    int i, err;

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

    mutex_lock(&c->umount_mutex);
    if (c->bgt) {
        kthread_stop(c->bgt);
        c->bgt = NULL;
    }

    dbg_save_space_info(c);

    for (i = 0; i < c->jhead_cnt; i++)
        ubifs_wbuf_sync(&c->jheads[i].wbuf);

    c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
    c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
    c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
    err = ubifs_write_master(c);
    if (err)
        ubifs_ro_mode(c, err);

    vfree(c->orph_buf);
    c->orph_buf = NULL;
    kfree(c->write_reserve_buf);
    c->write_reserve_buf = NULL;
    vfree(c->ileb_buf);
    c->ileb_buf = NULL;
    ubifs_lpt_free(c, 1);
    c->ro_mount = 1;
    err = dbg_check_space_info(c);
    if (err)
        ubifs_ro_mode(c, err);
    mutex_unlock(&c->umount_mutex);
}

static void ubifs_put_super(struct super_block *sb)
{
    int i;
    struct ubifs_info *c = sb->s_fs_info;

    ubifs_msg("un-mount UBI device %d, volume %d", c->vi.ubi_num,
          c->vi.vol_id);

    /*
     * The following asserts are only valid if there has not been a failure
     * of the media. For example, there will be dirty inodes if we failed
     * to write them back because of I/O errors.
     */
    if (!c->ro_error) {
        ubifs_assert(c->bi.idx_growth == 0);
        ubifs_assert(c->bi.dd_growth == 0);
        ubifs_assert(c->bi.data_growth == 0);
    }

    /*
     * The 'c->umount_lock' prevents races between UBIFS memory shrinker
     * and file system un-mount. Namely, it prevents the shrinker from
     * picking this superblock for shrinking - it will be just skipped if
     * the mutex is locked.
     */
    mutex_lock(&c->umount_mutex);
    if (!c->ro_mount) {
        /*
         * First of all kill the background thread to make sure it does
         * not interfere with un-mounting and freeing resources.
         */
        if (c->bgt) {
            kthread_stop(c->bgt);
            c->bgt = NULL;
        }

        /*
         * On fatal errors c->ro_error is set to 1, in which case we do
         * not write the master node.
         */
        if (!c->ro_error) {
            int err;

            /* Synchronize write-buffers */
            for (i = 0; i < c->jhead_cnt; i++)
                ubifs_wbuf_sync(&c->jheads[i].wbuf);

            /*
             * We are being cleanly unmounted which means the
             * orphans were killed - indicate this in the master
             * node. Also save the reserved GC LEB number.
             */
            c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_DIRTY);
            c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
            c->mst_node->gc_lnum = cpu_to_le32(c->gc_lnum);
            err = ubifs_write_master(c);
            if (err)
                /*
                 * Recovery will attempt to fix the master area
                 * next mount, so we just print a message and
                 * continue to unmount normally.
                 */
                ubifs_err("failed to write master node, error %d",
                      err);
        } else {
            for (i = 0; i < c->jhead_cnt; i++)
                /* Make sure write-buffer timers are canceled */
                hrtimer_cancel(&c->jheads[i].wbuf.timer);
        }
    }

    ubifs_umount(c);
    bdi_destroy(&c->bdi);
    ubi_close_volume(c->ubi);
    mutex_unlock(&c->umount_mutex);
}

static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
{
    int err;
    struct ubifs_info *c = sb->s_fs_info;

    dbg_gen("old flags %#lx, new flags %#x", sb->s_flags, *flags);

    err = ubifs_parse_options(c, data, 1);
    if (err) {
        ubifs_err("invalid or unknown remount parameter");
        return err;
    }

    if (c->ro_mount && !(*flags & MS_RDONLY)) {
        if (c->ro_error) {
            ubifs_msg("cannot re-mount R/W due to prior errors");
            return -EROFS;
        }
        if (c->ro_media) {
            ubifs_msg("cannot re-mount R/W - UBI volume is R/O");
            return -EROFS;
        }
        err = ubifs_remount_rw(c);
        if (err)
            return err;
    } else if (!c->ro_mount && (*flags & MS_RDONLY)) {
        if (c->ro_error) {
            ubifs_msg("cannot re-mount R/O due to prior errors");
            return -EROFS;
        }
        ubifs_remount_ro(c);
    }

    if (c->bulk_read == 1)
        bu_init(c);
    else {
        dbg_gen("disable bulk-read");
        kfree(c->bu.buf);
        c->bu.buf = NULL;
    }

    ubifs_assert(c->lst.taken_empty_lebs > 0);
    return 0;
}

const struct super_operations ubifs_super_operations = {
    .alloc_inode   = ubifs_alloc_inode,
    .destroy_inode = ubifs_destroy_inode,
    .put_super     = ubifs_put_super,
    .write_inode   = ubifs_write_inode,
    .evict_inode   = ubifs_evict_inode,
    .statfs        = ubifs_statfs,
    .dirty_inode   = ubifs_dirty_inode,
    .remount_fs    = ubifs_remount_fs,
    .show_options  = ubifs_show_options,
    .sync_fs       = ubifs_sync_fs,
};

static struct ubi_volume_desc *open_ubi(const char *name, int mode)
{
    struct ubi_volume_desc *ubi;
    int dev, vol;
    char *endptr;

    /* First, try to open using the device node path method */
    ubi = ubi_open_volume_path(name, mode);
    if (!IS_ERR(ubi))
        return ubi;

    /* Try the "nodev" method */
    if (name[0] != 'u' || name[1] != 'b' || name[2] != 'i')
        return ERR_PTR(-EINVAL);

    /* ubi:NAME method */
    if ((name[3] == ':' || name[3] == '!') && name[4] != '\0')
        return ubi_open_volume_nm(0, name + 4, mode);

    if (!isdigit(name[3]))
        return ERR_PTR(-EINVAL);

    dev = simple_strtoul(name + 3, &endptr, 0);

    /* ubiY method */
    if (*endptr == '\0')
        return ubi_open_volume(0, dev, mode);

    /* ubiX_Y method */
    if (*endptr == '_' && isdigit(endptr[1])) {
        vol = simple_strtoul(endptr + 1, &endptr, 0);
        if (*endptr != '\0')
            return ERR_PTR(-EINVAL);
        return ubi_open_volume(dev, vol, mode);
    }

    /* ubiX:NAME method */
    if ((*endptr == ':' || *endptr == '!') && endptr[1] != '\0')
        return ubi_open_volume_nm(dev, ++endptr, mode);

    return ERR_PTR(-EINVAL);
}

static struct ubifs_info *alloc_ubifs_info(struct ubi_volume_desc *ubi)
{
    struct ubifs_info *c;

    c = kzalloc(sizeof(struct ubifs_info), GFP_KERNEL);
    if (c) {
        spin_lock_init(&c->cnt_lock);
        spin_lock_init(&c->cs_lock);
        spin_lock_init(&c->buds_lock);
        spin_lock_init(&c->space_lock);
        spin_lock_init(&c->orphan_lock);
        init_rwsem(&c->commit_sem);
        mutex_init(&c->lp_mutex);
        mutex_init(&c->tnc_mutex);
        mutex_init(&c->log_mutex);
        mutex_init(&c->mst_mutex);
        mutex_init(&c->umount_mutex);
        mutex_init(&c->bu_mutex);
        mutex_init(&c->write_reserve_mutex);
        init_waitqueue_head(&c->cmt_wq);
        c->buds = RB_ROOT;
        c->old_idx = RB_ROOT;
        c->size_tree = RB_ROOT;
        c->orph_tree = RB_ROOT;
        INIT_LIST_HEAD(&c->infos_list);
        INIT_LIST_HEAD(&c->idx_gc);
        INIT_LIST_HEAD(&c->replay_list);
        INIT_LIST_HEAD(&c->replay_buds);
        INIT_LIST_HEAD(&c->uncat_list);
        INIT_LIST_HEAD(&c->empty_list);
        INIT_LIST_HEAD(&c->freeable_list);
        INIT_LIST_HEAD(&c->frdi_idx_list);
        INIT_LIST_HEAD(&c->unclean_leb_list);
        INIT_LIST_HEAD(&c->old_buds);
        INIT_LIST_HEAD(&c->orph_list);
        INIT_LIST_HEAD(&c->orph_new);
        c->no_chk_data_crc = 1;

        c->highest_inum = UBIFS_FIRST_INO;
        c->lhead_lnum = c->ltail_lnum = UBIFS_LOG_LNUM;

        ubi_get_volume_info(ubi, &c->vi);
        ubi_get_device_info(c->vi.ubi_num, &c->di);
    }
    return c;
}

static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct ubifs_info *c = sb->s_fs_info;
    struct inode *root;
    int err;

    c->vfs_sb = sb;
    /* Re-open the UBI device in read-write mode */
    c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READWRITE);
    if (IS_ERR(c->ubi)) {
        err = PTR_ERR(c->ubi);
        goto out;
    }

    /*
     * UBIFS provides 'backing_dev_info' in order to disable read-ahead. For
     * UBIFS, I/O is not deferred, it is done immediately in readpage,
     * which means the user would have to wait not just for their own I/O
     * but the read-ahead I/O as well i.e. completely pointless.
     *
     * Read-ahead will be disabled because @c->bdi.ra_pages is 0.
     */
    c->bdi.name = "ubifs",
    c->bdi.capabilities = BDI_CAP_MAP_COPY;
    err  = bdi_init(&c->bdi);
    if (err)
        goto out_close;
    err = bdi_register(&c->bdi, NULL, "ubifs_%d_%d",
               c->vi.ubi_num, c->vi.vol_id);
    if (err)
        goto out_bdi;

    err = ubifs_parse_options(c, data, 0);
    if (err)
        goto out_bdi;

    sb->s_bdi = &c->bdi;
    sb->s_fs_info = c;
    sb->s_magic = UBIFS_SUPER_MAGIC;
    sb->s_blocksize = UBIFS_BLOCK_SIZE;
    sb->s_blocksize_bits = UBIFS_BLOCK_SHIFT;
    sb->s_maxbytes = c->max_inode_sz = key_max_inode_size(c);
    if (c->max_inode_sz > MAX_LFS_FILESIZE)
        sb->s_maxbytes = c->max_inode_sz = MAX_LFS_FILESIZE;
    sb->s_op = &ubifs_super_operations;

    mutex_lock(&c->umount_mutex);
    err = mount_ubifs(c);
    if (err) {
        ubifs_assert(err < 0);
        goto out_unlock;
    }

    /* Read the root inode */
    root = ubifs_iget(sb, UBIFS_ROOT_INO);
    if (IS_ERR(root)) {
        err = PTR_ERR(root);
        goto out_umount;
    }

    sb->s_root = d_make_root(root);
    if (!sb->s_root)
        goto out_umount;

    mutex_unlock(&c->umount_mutex);
    return 0;

out_umount:
    ubifs_umount(c);
out_unlock:
    mutex_unlock(&c->umount_mutex);
out_bdi:
    bdi_destroy(&c->bdi);
out_close:
    ubi_close_volume(c->ubi);
out:
    return err;
}

static int sb_test(struct super_block *sb, void *data)
{
    struct ubifs_info *c1 = data;
    struct ubifs_info *c = sb->s_fs_info;

    return c->vi.cdev == c1->vi.cdev;
}

static int sb_set(struct super_block *sb, void *data)
{
    sb->s_fs_info = data;
    return set_anon_super(sb, NULL);
}

static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
            const char *name, void *data)
{
    struct ubi_volume_desc *ubi;
    struct ubifs_info *c;
    struct super_block *sb;
    int err;

    dbg_gen("name %s, flags %#x", name, flags);

    /*
     * Get UBI device number and volume ID. Mount it read-only so far
     * because this might be a new mount point, and UBI allows only one
     * read-write user at a time.
     */
    ubi = open_ubi(name, UBI_READONLY);
    if (IS_ERR(ubi)) {
        ubifs_err("cannot open \"%s\", error %d",
              name, (int)PTR_ERR(ubi));
        return ERR_CAST(ubi);
    }

    c = alloc_ubifs_info(ubi);
    if (!c) {
        err = -ENOMEM;
        goto out_close;
    }

    dbg_gen("opened ubi%d_%d", c->vi.ubi_num, c->vi.vol_id);

    sb = sget(fs_type, sb_test, sb_set, flags, c);
    if (IS_ERR(sb)) {
        err = PTR_ERR(sb);
        kfree(c);
        goto out_close;
    }

    if (sb->s_root) {
        struct ubifs_info *c1 = sb->s_fs_info;
        kfree(c);
        /* A new mount point for already mounted UBIFS */
        dbg_gen("this ubi volume is already mounted");
        if (!!(flags & MS_RDONLY) != c1->ro_mount) {
            err = -EBUSY;
            goto out_deact;
        }
    } else {
        err = ubifs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
        if (err)
            goto out_deact;
        /* We do not support atime */
        sb->s_flags |= MS_ACTIVE | MS_NOATIME;
    }

    /* 'fill_super()' opens ubi again so we must close it here */
    ubi_close_volume(ubi);

    return dget(sb->s_root);

out_deact:
    deactivate_locked_super(sb);
out_close:
    ubi_close_volume(ubi);
    return ERR_PTR(err);
}

static void kill_ubifs_super(struct super_block *s)
{
    struct ubifs_info *c = s->s_fs_info;
    kill_anon_super(s);
    kfree(c);
}

static struct file_system_type ubifs_fs_type = {
    .name    = "ubifs",
    .owner   = THIS_MODULE,
    .mount   = ubifs_mount,
    .kill_sb = kill_ubifs_super,
};

/*
 * Inode slab cache constructor.
 */
static void inode_slab_ctor(void *obj)
{
    struct ubifs_inode *ui = obj;
    inode_init_once(&ui->vfs_inode);
}

static int __init ubifs_init(void)
{
    int err;

    BUILD_BUG_ON(sizeof(struct ubifs_ch) != 24);

    /* Make sure node sizes are 8-byte aligned */
    BUILD_BUG_ON(UBIFS_CH_SZ        & 7);
    BUILD_BUG_ON(UBIFS_INO_NODE_SZ  & 7);
    BUILD_BUG_ON(UBIFS_DENT_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_XENT_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_DATA_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_SB_NODE_SZ   & 7);
    BUILD_BUG_ON(UBIFS_MST_NODE_SZ  & 7);
    BUILD_BUG_ON(UBIFS_REF_NODE_SZ  & 7);
    BUILD_BUG_ON(UBIFS_CS_NODE_SZ   & 7);
    BUILD_BUG_ON(UBIFS_ORPH_NODE_SZ & 7);

    BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ & 7);
    BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  & 7);
    BUILD_BUG_ON(UBIFS_MAX_NODE_SZ      & 7);
    BUILD_BUG_ON(MIN_WRITE_SZ           & 7);

    /* Check min. node size */
    BUILD_BUG_ON(UBIFS_INO_NODE_SZ  < MIN_WRITE_SZ);
    BUILD_BUG_ON(UBIFS_DENT_NODE_SZ < MIN_WRITE_SZ);
    BUILD_BUG_ON(UBIFS_XENT_NODE_SZ < MIN_WRITE_SZ);
    BUILD_BUG_ON(UBIFS_TRUN_NODE_SZ < MIN_WRITE_SZ);

    BUILD_BUG_ON(UBIFS_MAX_DENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
    BUILD_BUG_ON(UBIFS_MAX_XENT_NODE_SZ > UBIFS_MAX_NODE_SZ);
    BUILD_BUG_ON(UBIFS_MAX_DATA_NODE_SZ > UBIFS_MAX_NODE_SZ);
    BUILD_BUG_ON(UBIFS_MAX_INO_NODE_SZ  > UBIFS_MAX_NODE_SZ);

    /* Defined node sizes */
    BUILD_BUG_ON(UBIFS_SB_NODE_SZ  != 4096);
    BUILD_BUG_ON(UBIFS_MST_NODE_SZ != 512);
    BUILD_BUG_ON(UBIFS_INO_NODE_SZ != 160);
    BUILD_BUG_ON(UBIFS_REF_NODE_SZ != 64);

    /*
     * We use 2 bit wide bit-fields to store compression type, which should
     * be amended if more compressors are added. The bit-fields are:
     * @compr_type in 'struct ubifs_inode', @default_compr in
     * 'struct ubifs_info' and @compr_type in 'struct ubifs_mount_opts'.
     */
    BUILD_BUG_ON(UBIFS_COMPR_TYPES_CNT > 4);

    /*
     * We require that PAGE_CACHE_SIZE is greater-than-or-equal-to
     * UBIFS_BLOCK_SIZE. It is assumed that both are powers of 2.
     */
    if (PAGE_CACHE_SIZE < UBIFS_BLOCK_SIZE) {
        ubifs_err("VFS page cache size is %u bytes, but UBIFS requires at least 4096 bytes",
              (unsigned int)PAGE_CACHE_SIZE);
        return -EINVAL;
    }

    ubifs_inode_slab = kmem_cache_create("ubifs_inode_slab",
                sizeof(struct ubifs_inode), 0,
                SLAB_MEM_SPREAD | SLAB_RECLAIM_ACCOUNT,
                &inode_slab_ctor);
    if (!ubifs_inode_slab)
        return -ENOMEM;

    register_shrinker(&ubifs_shrinker_info);

    err = ubifs_compressors_init();
    if (err)
        goto out_shrinker;

    err = dbg_debugfs_init();
    if (err)
        goto out_compr;

    err = register_filesystem(&ubifs_fs_type);
    if (err) {
        ubifs_err("cannot register file system, error %d", err);
        goto out_dbg;
    }
    return 0;

out_dbg:
    dbg_debugfs_exit();
out_compr:
    ubifs_compressors_exit();
out_shrinker:
    unregister_shrinker(&ubifs_shrinker_info);
    kmem_cache_destroy(ubifs_inode_slab);
    return err;
}
/* late_initcall to let compressors initialize first */
late_initcall(ubifs_init);

static void __exit ubifs_exit(void)
{
    ubifs_assert(list_empty(&ubifs_infos));
    ubifs_assert(atomic_long_read(&ubifs_clean_zn_cnt) == 0);

    dbg_debugfs_exit();
    ubifs_compressors_exit();
    unregister_shrinker(&ubifs_shrinker_info);

    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(ubifs_inode_slab);
    unregister_filesystem(&ubifs_fs_type);
}
module_exit(ubifs_exit);

MODULE_LICENSE("GPL");
MODULE_VERSION(__stringify(UBIFS_VERSION));
MODULE_AUTHOR("Artem Bityutskiy, Adrian Hunter");
MODULE_DESCRIPTION("UBIFS - UBI File System");