inode.c

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/*
 *  linux/fs/fat/inode.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
 *  Rewritten for the constant inumbers support by Al Viro
 *
 *  Fixes:
 *
 *  Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/mpage.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/parser.h>
#include <linux/uio.h>
#include <linux/writeback.h>
#include <linux/log2.h>
#include <linux/hash.h>
#include <asm/unaligned.h>
#include "fat.h"

#ifndef CONFIG_FAT_DEFAULT_IOCHARSET
/* if user don't select VFAT, this is undefined. */
#define CONFIG_FAT_DEFAULT_IOCHARSET    ""
#endif

static int fat_default_codepage = CONFIG_FAT_DEFAULT_CODEPAGE;
static char fat_default_iocharset[] = CONFIG_FAT_DEFAULT_IOCHARSET;


static int fat_add_cluster(struct inode *inode)
{
    int err, cluster;

    err = fat_alloc_clusters(inode, &cluster, 1);
    if (err)
        return err;
    /* FIXME: this cluster should be added after data of this
     * cluster is writed */
    err = fat_chain_add(inode, cluster, 1);
    if (err)
        fat_free_clusters(inode, cluster);
    return err;
}

static inline int __fat_get_block(struct inode *inode, sector_t iblock,
                  unsigned long *max_blocks,
                  struct buffer_head *bh_result, int create)
{
    struct super_block *sb = inode->i_sb;
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    unsigned long mapped_blocks;
    sector_t phys;
    int err, offset;

    err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
    if (err)
        return err;
    if (phys) {
        map_bh(bh_result, sb, phys);
        *max_blocks = min(mapped_blocks, *max_blocks);
        return 0;
    }
    if (!create)
        return 0;

    if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
        fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
            MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
        return -EIO;
    }

    offset = (unsigned long)iblock & (sbi->sec_per_clus - 1);
    if (!offset) {
        /* TODO: multiple cluster allocation would be desirable. */
        err = fat_add_cluster(inode);
        if (err)
            return err;
    }
    /* available blocks on this cluster */
    mapped_blocks = sbi->sec_per_clus - offset;

    *max_blocks = min(mapped_blocks, *max_blocks);
    MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;

    err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
    if (err)
        return err;

    BUG_ON(!phys);
    BUG_ON(*max_blocks != mapped_blocks);
    set_buffer_new(bh_result);
    map_bh(bh_result, sb, phys);

    return 0;
}

static int fat_get_block(struct inode *inode, sector_t iblock,
             struct buffer_head *bh_result, int create)
{
    struct super_block *sb = inode->i_sb;
    unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
    int err;

    err = __fat_get_block(inode, iblock, &max_blocks, bh_result, create);
    if (err)
        return err;
    bh_result->b_size = max_blocks << sb->s_blocksize_bits;
    return 0;
}

static int fat_writepage(struct page *page, struct writeback_control *wbc)
{
    return block_write_full_page(page, fat_get_block, wbc);
}

static int fat_writepages(struct address_space *mapping,
              struct writeback_control *wbc)
{
    return mpage_writepages(mapping, wbc, fat_get_block);
}

static int fat_readpage(struct file *file, struct page *page)
{
    return mpage_readpage(page, fat_get_block);
}

static int fat_readpages(struct file *file, struct address_space *mapping,
             struct list_head *pages, unsigned nr_pages)
{
    return mpage_readpages(mapping, pages, nr_pages, fat_get_block);
}

static void fat_write_failed(struct address_space *mapping, loff_t to)
{
    struct inode *inode = mapping->host;

    if (to > inode->i_size) {
        truncate_pagecache(inode, to, inode->i_size);
        fat_truncate_blocks(inode, inode->i_size);
    }
}

static int fat_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
    int err;

    *pagep = NULL;
    err = cont_write_begin(file, mapping, pos, len, flags,
                pagep, fsdata, fat_get_block,
                &MSDOS_I(mapping->host)->mmu_private);
    if (err < 0)
        fat_write_failed(mapping, pos + len);
    return err;
}

static int fat_write_end(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned copied,
            struct page *pagep, void *fsdata)
{
    struct inode *inode = mapping->host;
    int err;
    err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
    if (err < len)
        fat_write_failed(mapping, pos + len);
    if (!(err < 0) && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
        inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
        MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
        mark_inode_dirty(inode);
    }
    return err;
}

static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
                 const struct iovec *iov,
                 loff_t offset, unsigned long nr_segs)
{
    struct file *file = iocb->ki_filp;
    struct address_space *mapping = file->f_mapping;
    struct inode *inode = mapping->host;
    ssize_t ret;

    if (rw == WRITE) {
        /*
         * FIXME: blockdev_direct_IO() doesn't use ->write_begin(),
         * so we need to update the ->mmu_private to block boundary.
         *
         * But we must fill the remaining area or hole by nul for
         * updating ->mmu_private.
         *
         * Return 0, and fallback to normal buffered write.
         */
        loff_t size = offset + iov_length(iov, nr_segs);
        if (MSDOS_I(inode)->mmu_private < size)
            return 0;
    }

    /*
     * FAT need to use the DIO_LOCKING for avoiding the race
     * condition of fat_get_block() and ->truncate().
     */
    ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
                 fat_get_block);
    if (ret < 0 && (rw & WRITE))
        fat_write_failed(mapping, offset + iov_length(iov, nr_segs));

    return ret;
}

static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
{
    sector_t blocknr;

    /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
    down_read(&MSDOS_I(mapping->host)->truncate_lock);
    blocknr = generic_block_bmap(mapping, block, fat_get_block);
    up_read(&MSDOS_I(mapping->host)->truncate_lock);

    return blocknr;
}

static const struct address_space_operations fat_aops = {
    .readpage   = fat_readpage,
    .readpages  = fat_readpages,
    .writepage  = fat_writepage,
    .writepages = fat_writepages,
    .write_begin    = fat_write_begin,
    .write_end  = fat_write_end,
    .direct_IO  = fat_direct_IO,
    .bmap       = _fat_bmap
};

/*
 * New FAT inode stuff. We do the following:
 *  a) i_ino is constant and has nothing with on-disk location.
 *  b) FAT manages its own cache of directory entries.
 *  c) *This* cache is indexed by on-disk location.
 *  d) inode has an associated directory entry, all right, but
 *      it may be unhashed.
 *  e) currently entries are stored within struct inode. That should
 *      change.
 *  f) we deal with races in the following way:
 *      1. readdir() and lookup() do FAT-dir-cache lookup.
 *      2. rename() unhashes the F-d-c entry and rehashes it in
 *          a new place.
 *      3. unlink() and rmdir() unhash F-d-c entry.
 *      4. fat_write_inode() checks whether the thing is unhashed.
 *          If it is we silently return. If it isn't we do bread(),
 *          check if the location is still valid and retry if it
 *          isn't. Otherwise we do changes.
 *      5. Spinlock is used to protect hash/unhash/location check/lookup
 *      6. fat_evict_inode() unhashes the F-d-c entry.
 *      7. lookup() and readdir() do igrab() if they find a F-d-c entry
 *          and consider negative result as cache miss.
 */

static void fat_hash_init(struct super_block *sb)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    int i;

    spin_lock_init(&sbi->inode_hash_lock);
    for (i = 0; i < FAT_HASH_SIZE; i++)
        INIT_HLIST_HEAD(&sbi->inode_hashtable[i]);
}

static inline unsigned long fat_hash(loff_t i_pos)
{
    return hash_32(i_pos, FAT_HASH_BITS);
}

static void dir_hash_init(struct super_block *sb)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    int i;

    spin_lock_init(&sbi->dir_hash_lock);
    for (i = 0; i < FAT_HASH_SIZE; i++)
        INIT_HLIST_HEAD(&sbi->dir_hashtable[i]);
}

void fat_attach(struct inode *inode, loff_t i_pos)
{
    struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

    if (inode->i_ino != MSDOS_ROOT_INO) {
        struct hlist_head *head =   sbi->inode_hashtable
                      + fat_hash(i_pos);

        spin_lock(&sbi->inode_hash_lock);
        MSDOS_I(inode)->i_pos = i_pos;
        hlist_add_head(&MSDOS_I(inode)->i_fat_hash, head);
        spin_unlock(&sbi->inode_hash_lock);
    }

    /* If NFS support is enabled, cache the mapping of start cluster
     * to directory inode. This is used during reconnection of
     * dentries to the filesystem root.
     */
    if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
        struct hlist_head *d_head = sbi->dir_hashtable;
        d_head += fat_dir_hash(MSDOS_I(inode)->i_logstart);

        spin_lock(&sbi->dir_hash_lock);
        hlist_add_head(&MSDOS_I(inode)->i_dir_hash, d_head);
        spin_unlock(&sbi->dir_hash_lock);
    }
}
EXPORT_SYMBOL_GPL(fat_attach);

void fat_detach(struct inode *inode)
{
    struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
    spin_lock(&sbi->inode_hash_lock);
    MSDOS_I(inode)->i_pos = 0;
    hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
    spin_unlock(&sbi->inode_hash_lock);

    if (S_ISDIR(inode->i_mode) && sbi->options.nfs) {
        spin_lock(&sbi->dir_hash_lock);
        hlist_del_init(&MSDOS_I(inode)->i_dir_hash);
        spin_unlock(&sbi->dir_hash_lock);
    }
}
EXPORT_SYMBOL_GPL(fat_detach);

struct inode *fat_iget(struct super_block *sb, loff_t i_pos)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    struct hlist_head *head = sbi->inode_hashtable + fat_hash(i_pos);
    struct hlist_node *_p;
    struct msdos_inode_info *i;
    struct inode *inode = NULL;

    spin_lock(&sbi->inode_hash_lock);
    hlist_for_each_entry(i, _p, head, i_fat_hash) {
        BUG_ON(i->vfs_inode.i_sb != sb);
        if (i->i_pos != i_pos)
            continue;
        inode = igrab(&i->vfs_inode);
        if (inode)
            break;
    }
    spin_unlock(&sbi->inode_hash_lock);
    return inode;
}

static int is_exec(unsigned char *extension)
{
    unsigned char *exe_extensions = "EXECOMBAT", *walk;

    for (walk = exe_extensions; *walk; walk += 3)
        if (!strncmp(extension, walk, 3))
            return 1;
    return 0;
}

static int fat_calc_dir_size(struct inode *inode)
{
    struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
    int ret, fclus, dclus;

    inode->i_size = 0;
    if (MSDOS_I(inode)->i_start == 0)
        return 0;

    ret = fat_get_cluster(inode, FAT_ENT_EOF, &fclus, &dclus);
    if (ret < 0)
        return ret;
    inode->i_size = (fclus + 1) << sbi->cluster_bits;

    return 0;
}

/* doesn't deal with root inode */
static int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
{
    struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
    int error;

    MSDOS_I(inode)->i_pos = 0;
    inode->i_uid = sbi->options.fs_uid;
    inode->i_gid = sbi->options.fs_gid;
    inode->i_version++;
    inode->i_generation = get_seconds();

    if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
        inode->i_generation &= ~1;
        inode->i_mode = fat_make_mode(sbi, de->attr, S_IRWXUGO);
        inode->i_op = sbi->dir_ops;
        inode->i_fop = &fat_dir_operations;

        MSDOS_I(inode)->i_start = fat_get_start(sbi, de);
        MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
        error = fat_calc_dir_size(inode);
        if (error < 0)
            return error;
        MSDOS_I(inode)->mmu_private = inode->i_size;

        set_nlink(inode, fat_subdirs(inode));
    } else { /* not a directory */
        inode->i_generation |= 1;
        inode->i_mode = fat_make_mode(sbi, de->attr,
            ((sbi->options.showexec && !is_exec(de->name + 8))
             ? S_IRUGO|S_IWUGO : S_IRWXUGO));
        MSDOS_I(inode)->i_start = fat_get_start(sbi, de);

        MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
        inode->i_size = le32_to_cpu(de->size);
        inode->i_op = &fat_file_inode_operations;
        inode->i_fop = &fat_file_operations;
        inode->i_mapping->a_ops = &fat_aops;
        MSDOS_I(inode)->mmu_private = inode->i_size;
    }
    if (de->attr & ATTR_SYS) {
        if (sbi->options.sys_immutable)
            inode->i_flags |= S_IMMUTABLE;
    }
    fat_save_attrs(inode, de->attr);

    inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
               & ~((loff_t)sbi->cluster_size - 1)) >> 9;

    fat_time_fat2unix(sbi, &inode->i_mtime, de->time, de->date, 0);
    if (sbi->options.isvfat) {
        fat_time_fat2unix(sbi, &inode->i_ctime, de->ctime,
                  de->cdate, de->ctime_cs);
        fat_time_fat2unix(sbi, &inode->i_atime, 0, de->adate, 0);
    } else
        inode->i_ctime = inode->i_atime = inode->i_mtime;

    return 0;
}

struct inode *fat_build_inode(struct super_block *sb,
            struct msdos_dir_entry *de, loff_t i_pos)
{
    struct inode *inode;
    int err;

    inode = fat_iget(sb, i_pos);
    if (inode)
        goto out;
    inode = new_inode(sb);
    if (!inode) {
        inode = ERR_PTR(-ENOMEM);
        goto out;
    }
    inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
    inode->i_version = 1;
    err = fat_fill_inode(inode, de);
    if (err) {
        iput(inode);
        inode = ERR_PTR(err);
        goto out;
    }
    fat_attach(inode, i_pos);
    insert_inode_hash(inode);
out:
    return inode;
}

EXPORT_SYMBOL_GPL(fat_build_inode);

static void fat_evict_inode(struct inode *inode)
{
    truncate_inode_pages(&inode->i_data, 0);
    if (!inode->i_nlink) {
        inode->i_size = 0;
        fat_truncate_blocks(inode, 0);
    }
    invalidate_inode_buffers(inode);
    clear_inode(inode);
    fat_cache_inval_inode(inode);
    fat_detach(inode);
}

static void fat_put_super(struct super_block *sb)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);

    iput(sbi->fsinfo_inode);
    iput(sbi->fat_inode);

    unload_nls(sbi->nls_disk);
    unload_nls(sbi->nls_io);

    if (sbi->options.iocharset != fat_default_iocharset)
        kfree(sbi->options.iocharset);

    sb->s_fs_info = NULL;
    kfree(sbi);
}

static struct kmem_cache *fat_inode_cachep;

static struct inode *fat_alloc_inode(struct super_block *sb)
{
    struct msdos_inode_info *ei;
    ei = kmem_cache_alloc(fat_inode_cachep, GFP_NOFS);
    if (!ei)
        return NULL;

    init_rwsem(&ei->truncate_lock);
    return &ei->vfs_inode;
}

static void fat_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
}

static void fat_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, fat_i_callback);
}

static void init_once(void *foo)
{
    struct msdos_inode_info *ei = (struct msdos_inode_info *)foo;

    spin_lock_init(&ei->cache_lru_lock);
    ei->nr_caches = 0;
    ei->cache_valid_id = FAT_CACHE_VALID + 1;
    INIT_LIST_HEAD(&ei->cache_lru);
    INIT_HLIST_NODE(&ei->i_fat_hash);
    INIT_HLIST_NODE(&ei->i_dir_hash);
    inode_init_once(&ei->vfs_inode);
}

static int __init fat_init_inodecache(void)
{
    fat_inode_cachep = kmem_cache_create("fat_inode_cache",
                         sizeof(struct msdos_inode_info),
                         0, (SLAB_RECLAIM_ACCOUNT|
                        SLAB_MEM_SPREAD),
                         init_once);
    if (fat_inode_cachep == NULL)
        return -ENOMEM;
    return 0;
}

static void __exit fat_destroy_inodecache(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(fat_inode_cachep);
}

static int fat_remount(struct super_block *sb, int *flags, char *data)
{
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    *flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
    return 0;
}

static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

    /* If the count of free cluster is still unknown, counts it here. */
    if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
        int err = fat_count_free_clusters(dentry->d_sb);
        if (err)
            return err;
    }

    buf->f_type = dentry->d_sb->s_magic;
    buf->f_bsize = sbi->cluster_size;
    buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
    buf->f_bfree = sbi->free_clusters;
    buf->f_bavail = sbi->free_clusters;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);
    buf->f_namelen =
        (sbi->options.isvfat ? FAT_LFN_LEN : 12) * NLS_MAX_CHARSET_SIZE;

    return 0;
}

static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
                    struct inode *inode)
{
    loff_t i_pos;
#if BITS_PER_LONG == 32
    spin_lock(&sbi->inode_hash_lock);
#endif
    i_pos = MSDOS_I(inode)->i_pos;
#if BITS_PER_LONG == 32
    spin_unlock(&sbi->inode_hash_lock);
#endif
    return i_pos;
}

static int __fat_write_inode(struct inode *inode, int wait)
{
    struct super_block *sb = inode->i_sb;
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    struct buffer_head *bh;
    struct msdos_dir_entry *raw_entry;
    loff_t i_pos;
    int err;

    if (inode->i_ino == MSDOS_ROOT_INO)
        return 0;

retry:
    i_pos = fat_i_pos_read(sbi, inode);
    if (!i_pos)
        return 0;

    bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
    if (!bh) {
        fat_msg(sb, KERN_ERR, "unable to read inode block "
               "for updating (i_pos %lld)", i_pos);
        return -EIO;
    }
    spin_lock(&sbi->inode_hash_lock);
    if (i_pos != MSDOS_I(inode)->i_pos) {
        spin_unlock(&sbi->inode_hash_lock);
        brelse(bh);
        goto retry;
    }

    raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
        [i_pos & (sbi->dir_per_block - 1)];
    if (S_ISDIR(inode->i_mode))
        raw_entry->size = 0;
    else
        raw_entry->size = cpu_to_le32(inode->i_size);
    raw_entry->attr = fat_make_attrs(inode);
    fat_set_start(raw_entry, MSDOS_I(inode)->i_logstart);
    fat_time_unix2fat(sbi, &inode->i_mtime, &raw_entry->time,
              &raw_entry->date, NULL);
    if (sbi->options.isvfat) {
        __le16 atime;
        fat_time_unix2fat(sbi, &inode->i_ctime, &raw_entry->ctime,
                  &raw_entry->cdate, &raw_entry->ctime_cs);
        fat_time_unix2fat(sbi, &inode->i_atime, &atime,
                  &raw_entry->adate, NULL);
    }
    spin_unlock(&sbi->inode_hash_lock);
    mark_buffer_dirty(bh);
    err = 0;
    if (wait)
        err = sync_dirty_buffer(bh);
    brelse(bh);
    return err;
}

static int fat_write_inode(struct inode *inode, struct writeback_control *wbc)
{
    int err;

    if (inode->i_ino == MSDOS_FSINFO_INO) {
        struct super_block *sb = inode->i_sb;

        mutex_lock(&MSDOS_SB(sb)->s_lock);
        err = fat_clusters_flush(sb);
        mutex_unlock(&MSDOS_SB(sb)->s_lock);
    } else
        err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);

    return err;
}

int fat_sync_inode(struct inode *inode)
{
    return __fat_write_inode(inode, 1);
}

EXPORT_SYMBOL_GPL(fat_sync_inode);

static int fat_show_options(struct seq_file *m, struct dentry *root);
static const struct super_operations fat_sops = {
    .alloc_inode    = fat_alloc_inode,
    .destroy_inode  = fat_destroy_inode,
    .write_inode    = fat_write_inode,
    .evict_inode    = fat_evict_inode,
    .put_super  = fat_put_super,
    .statfs     = fat_statfs,
    .remount_fs = fat_remount,

    .show_options   = fat_show_options,
};

static const struct export_operations fat_export_ops = {
    .fh_to_dentry   = fat_fh_to_dentry,
    .fh_to_parent   = fat_fh_to_parent,
    .get_parent = fat_get_parent,
};

static int fat_show_options(struct seq_file *m, struct dentry *root)
{
    struct msdos_sb_info *sbi = MSDOS_SB(root->d_sb);
    struct fat_mount_options *opts = &sbi->options;
    int isvfat = opts->isvfat;

    if (!uid_eq(opts->fs_uid, GLOBAL_ROOT_UID))
        seq_printf(m, ",uid=%u",
                from_kuid_munged(&init_user_ns, opts->fs_uid));
    if (!gid_eq(opts->fs_gid, GLOBAL_ROOT_GID))
        seq_printf(m, ",gid=%u",
                from_kgid_munged(&init_user_ns, opts->fs_gid));
    seq_printf(m, ",fmask=%04o", opts->fs_fmask);
    seq_printf(m, ",dmask=%04o", opts->fs_dmask);
    if (opts->allow_utime)
        seq_printf(m, ",allow_utime=%04o", opts->allow_utime);
    if (sbi->nls_disk)
        seq_printf(m, ",codepage=%s", sbi->nls_disk->charset);
    if (isvfat) {
        if (sbi->nls_io)
            seq_printf(m, ",iocharset=%s", sbi->nls_io->charset);

        switch (opts->shortname) {
        case VFAT_SFN_DISPLAY_WIN95 | VFAT_SFN_CREATE_WIN95:
            seq_puts(m, ",shortname=win95");
            break;
        case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WINNT:
            seq_puts(m, ",shortname=winnt");
            break;
        case VFAT_SFN_DISPLAY_WINNT | VFAT_SFN_CREATE_WIN95:
            seq_puts(m, ",shortname=mixed");
            break;
        case VFAT_SFN_DISPLAY_LOWER | VFAT_SFN_CREATE_WIN95:
            seq_puts(m, ",shortname=lower");
            break;
        default:
            seq_puts(m, ",shortname=unknown");
            break;
        }
    }
    if (opts->name_check != 'n')
        seq_printf(m, ",check=%c", opts->name_check);
    if (opts->usefree)
        seq_puts(m, ",usefree");
    if (opts->quiet)
        seq_puts(m, ",quiet");
    if (opts->nfs)
        seq_puts(m, ",nfs");
    if (opts->showexec)
        seq_puts(m, ",showexec");
    if (opts->sys_immutable)
        seq_puts(m, ",sys_immutable");
    if (!isvfat) {
        if (opts->dotsOK)
            seq_puts(m, ",dotsOK=yes");
        if (opts->nocase)
            seq_puts(m, ",nocase");
    } else {
        if (opts->utf8)
            seq_puts(m, ",utf8");
        if (opts->unicode_xlate)
            seq_puts(m, ",uni_xlate");
        if (!opts->numtail)
            seq_puts(m, ",nonumtail");
        if (opts->rodir)
            seq_puts(m, ",rodir");
    }
    if (opts->flush)
        seq_puts(m, ",flush");
    if (opts->tz_utc)
        seq_puts(m, ",tz=UTC");
    if (opts->errors == FAT_ERRORS_CONT)
        seq_puts(m, ",errors=continue");
    else if (opts->errors == FAT_ERRORS_PANIC)
        seq_puts(m, ",errors=panic");
    else
        seq_puts(m, ",errors=remount-ro");
    if (opts->discard)
        seq_puts(m, ",discard");

    return 0;
}

enum {
    Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
    Opt_umask, Opt_dmask, Opt_fmask, Opt_allow_utime, Opt_codepage,
    Opt_usefree, Opt_nocase, Opt_quiet, Opt_showexec, Opt_debug,
    Opt_immutable, Opt_dots, Opt_nodots,
    Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
    Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
    Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
    Opt_obsolete, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
    Opt_err_panic, Opt_err_ro, Opt_discard, Opt_nfs, Opt_err,
};

static const match_table_t fat_tokens = {
    {Opt_check_r, "check=relaxed"},
    {Opt_check_s, "check=strict"},
    {Opt_check_n, "check=normal"},
    {Opt_check_r, "check=r"},
    {Opt_check_s, "check=s"},
    {Opt_check_n, "check=n"},
    {Opt_uid, "uid=%u"},
    {Opt_gid, "gid=%u"},
    {Opt_umask, "umask=%o"},
    {Opt_dmask, "dmask=%o"},
    {Opt_fmask, "fmask=%o"},
    {Opt_allow_utime, "allow_utime=%o"},
    {Opt_codepage, "codepage=%u"},
    {Opt_usefree, "usefree"},
    {Opt_nocase, "nocase"},
    {Opt_quiet, "quiet"},
    {Opt_showexec, "showexec"},
    {Opt_debug, "debug"},
    {Opt_immutable, "sys_immutable"},
    {Opt_flush, "flush"},
    {Opt_tz_utc, "tz=UTC"},
    {Opt_err_cont, "errors=continue"},
    {Opt_err_panic, "errors=panic"},
    {Opt_err_ro, "errors=remount-ro"},
    {Opt_discard, "discard"},
    {Opt_nfs, "nfs"},
    {Opt_obsolete, "conv=binary"},
    {Opt_obsolete, "conv=text"},
    {Opt_obsolete, "conv=auto"},
    {Opt_obsolete, "conv=b"},
    {Opt_obsolete, "conv=t"},
    {Opt_obsolete, "conv=a"},
    {Opt_obsolete, "fat=%u"},
    {Opt_obsolete, "blocksize=%u"},
    {Opt_obsolete, "cvf_format=%20s"},
    {Opt_obsolete, "cvf_options=%100s"},
    {Opt_obsolete, "posix"},
    {Opt_err, NULL},
};
static const match_table_t msdos_tokens = {
    {Opt_nodots, "nodots"},
    {Opt_nodots, "dotsOK=no"},
    {Opt_dots, "dots"},
    {Opt_dots, "dotsOK=yes"},
    {Opt_err, NULL}
};
static const match_table_t vfat_tokens = {
    {Opt_charset, "iocharset=%s"},
    {Opt_shortname_lower, "shortname=lower"},
    {Opt_shortname_win95, "shortname=win95"},
    {Opt_shortname_winnt, "shortname=winnt"},
    {Opt_shortname_mixed, "shortname=mixed"},
    {Opt_utf8_no, "utf8=0"},        /* 0 or no or false */
    {Opt_utf8_no, "utf8=no"},
    {Opt_utf8_no, "utf8=false"},
    {Opt_utf8_yes, "utf8=1"},       /* empty or 1 or yes or true */
    {Opt_utf8_yes, "utf8=yes"},
    {Opt_utf8_yes, "utf8=true"},
    {Opt_utf8_yes, "utf8"},
    {Opt_uni_xl_no, "uni_xlate=0"},     /* 0 or no or false */
    {Opt_uni_xl_no, "uni_xlate=no"},
    {Opt_uni_xl_no, "uni_xlate=false"},
    {Opt_uni_xl_yes, "uni_xlate=1"},    /* empty or 1 or yes or true */
    {Opt_uni_xl_yes, "uni_xlate=yes"},
    {Opt_uni_xl_yes, "uni_xlate=true"},
    {Opt_uni_xl_yes, "uni_xlate"},
    {Opt_nonumtail_no, "nonumtail=0"},  /* 0 or no or false */
    {Opt_nonumtail_no, "nonumtail=no"},
    {Opt_nonumtail_no, "nonumtail=false"},
    {Opt_nonumtail_yes, "nonumtail=1"}, /* empty or 1 or yes or true */
    {Opt_nonumtail_yes, "nonumtail=yes"},
    {Opt_nonumtail_yes, "nonumtail=true"},
    {Opt_nonumtail_yes, "nonumtail"},
    {Opt_rodir, "rodir"},
    {Opt_err, NULL}
};

static int parse_options(struct super_block *sb, char *options, int is_vfat,
             int silent, int *debug, struct fat_mount_options *opts)
{
    char *p;
    substring_t args[MAX_OPT_ARGS];
    int option;
    char *iocharset;

    opts->isvfat = is_vfat;

    opts->fs_uid = current_uid();
    opts->fs_gid = current_gid();
    opts->fs_fmask = opts->fs_dmask = current_umask();
    opts->allow_utime = -1;
    opts->codepage = fat_default_codepage;
    opts->iocharset = fat_default_iocharset;
    if (is_vfat) {
        opts->shortname = VFAT_SFN_DISPLAY_WINNT|VFAT_SFN_CREATE_WIN95;
        opts->rodir = 0;
    } else {
        opts->shortname = 0;
        opts->rodir = 1;
    }
    opts->name_check = 'n';
    opts->quiet = opts->showexec = opts->sys_immutable = opts->dotsOK =  0;
    opts->utf8 = opts->unicode_xlate = 0;
    opts->numtail = 1;
    opts->usefree = opts->nocase = 0;
    opts->tz_utc = 0;
    opts->nfs = 0;
    opts->errors = FAT_ERRORS_RO;
    *debug = 0;

    if (!options)
        goto out;

    while ((p = strsep(&options, ",")) != NULL) {
        int token;
        if (!*p)
            continue;

        token = match_token(p, fat_tokens, args);
        if (token == Opt_err) {
            if (is_vfat)
                token = match_token(p, vfat_tokens, args);
            else
                token = match_token(p, msdos_tokens, args);
        }
        switch (token) {
        case Opt_check_s:
            opts->name_check = 's';
            break;
        case Opt_check_r:
            opts->name_check = 'r';
            break;
        case Opt_check_n:
            opts->name_check = 'n';
            break;
        case Opt_usefree:
            opts->usefree = 1;
            break;
        case Opt_nocase:
            if (!is_vfat)
                opts->nocase = 1;
            else {
                /* for backward compatibility */
                opts->shortname = VFAT_SFN_DISPLAY_WIN95
                    | VFAT_SFN_CREATE_WIN95;
            }
            break;
        case Opt_quiet:
            opts->quiet = 1;
            break;
        case Opt_showexec:
            opts->showexec = 1;
            break;
        case Opt_debug:
            *debug = 1;
            break;
        case Opt_immutable:
            opts->sys_immutable = 1;
            break;
        case Opt_uid:
            if (match_int(&args[0], &option))
                return 0;
            opts->fs_uid = make_kuid(current_user_ns(), option);
            if (!uid_valid(opts->fs_uid))
                return 0;
            break;
        case Opt_gid:
            if (match_int(&args[0], &option))
                return 0;
            opts->fs_gid = make_kgid(current_user_ns(), option);
            if (!gid_valid(opts->fs_gid))
                return 0;
            break;
        case Opt_umask:
            if (match_octal(&args[0], &option))
                return 0;
            opts->fs_fmask = opts->fs_dmask = option;
            break;
        case Opt_dmask:
            if (match_octal(&args[0], &option))
                return 0;
            opts->fs_dmask = option;
            break;
        case Opt_fmask:
            if (match_octal(&args[0], &option))
                return 0;
            opts->fs_fmask = option;
            break;
        case Opt_allow_utime:
            if (match_octal(&args[0], &option))
                return 0;
            opts->allow_utime = option & (S_IWGRP | S_IWOTH);
            break;
        case Opt_codepage:
            if (match_int(&args[0], &option))
                return 0;
            opts->codepage = option;
            break;
        case Opt_flush:
            opts->flush = 1;
            break;
        case Opt_tz_utc:
            opts->tz_utc = 1;
            break;
        case Opt_err_cont:
            opts->errors = FAT_ERRORS_CONT;
            break;
        case Opt_err_panic:
            opts->errors = FAT_ERRORS_PANIC;
            break;
        case Opt_err_ro:
            opts->errors = FAT_ERRORS_RO;
            break;

        /* msdos specific */
        case Opt_dots:
            opts->dotsOK = 1;
            break;
        case Opt_nodots:
            opts->dotsOK = 0;
            break;

        /* vfat specific */
        case Opt_charset:
            if (opts->iocharset != fat_default_iocharset)
                kfree(opts->iocharset);
            iocharset = match_strdup(&args[0]);
            if (!iocharset)
                return -ENOMEM;
            opts->iocharset = iocharset;
            break;
        case Opt_shortname_lower:
            opts->shortname = VFAT_SFN_DISPLAY_LOWER
                    | VFAT_SFN_CREATE_WIN95;
            break;
        case Opt_shortname_win95:
            opts->shortname = VFAT_SFN_DISPLAY_WIN95
                    | VFAT_SFN_CREATE_WIN95;
            break;
        case Opt_shortname_winnt:
            opts->shortname = VFAT_SFN_DISPLAY_WINNT
                    | VFAT_SFN_CREATE_WINNT;
            break;
        case Opt_shortname_mixed:
            opts->shortname = VFAT_SFN_DISPLAY_WINNT
                    | VFAT_SFN_CREATE_WIN95;
            break;
        case Opt_utf8_no:       /* 0 or no or false */
            opts->utf8 = 0;
            break;
        case Opt_utf8_yes:      /* empty or 1 or yes or true */
            opts->utf8 = 1;
            break;
        case Opt_uni_xl_no:     /* 0 or no or false */
            opts->unicode_xlate = 0;
            break;
        case Opt_uni_xl_yes:        /* empty or 1 or yes or true */
            opts->unicode_xlate = 1;
            break;
        case Opt_nonumtail_no:      /* 0 or no or false */
            opts->numtail = 1;  /* negated option */
            break;
        case Opt_nonumtail_yes:     /* empty or 1 or yes or true */
            opts->numtail = 0;  /* negated option */
            break;
        case Opt_rodir:
            opts->rodir = 1;
            break;
        case Opt_discard:
            opts->discard = 1;
            break;
        case Opt_nfs:
            opts->nfs = 1;
            break;

        /* obsolete mount options */
        case Opt_obsolete:
            fat_msg(sb, KERN_INFO, "\"%s\" option is obsolete, "
                   "not supported now", p);
            break;
        /* unknown option */
        default:
            if (!silent) {
                fat_msg(sb, KERN_ERR,
                       "Unrecognized mount option \"%s\" "
                       "or missing value", p);
            }
            return -EINVAL;
        }
    }

out:
    /* UTF-8 doesn't provide FAT semantics */
    if (!strcmp(opts->iocharset, "utf8")) {
        fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset"
               " for FAT filesystems, filesystem will be "
               "case sensitive!");
    }

    /* If user doesn't specify allow_utime, it's initialized from dmask. */
    if (opts->allow_utime == (unsigned short)-1)
        opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH);
    if (opts->unicode_xlate)
        opts->utf8 = 0;

    return 0;
}

static int fat_read_root(struct inode *inode)
{
    struct super_block *sb = inode->i_sb;
    struct msdos_sb_info *sbi = MSDOS_SB(sb);
    int error;

    MSDOS_I(inode)->i_pos = 0;
    inode->i_uid = sbi->options.fs_uid;
    inode->i_gid = sbi->options.fs_gid;
    inode->i_version++;
    inode->i_generation = 0;
    inode->i_mode = fat_make_mode(sbi, ATTR_DIR, S_IRWXUGO);
    inode->i_op = sbi->dir_ops;
    inode->i_fop = &fat_dir_operations;
    if (sbi->fat_bits == 32) {
        MSDOS_I(inode)->i_start = sbi->root_cluster;
        error = fat_calc_dir_size(inode);
        if (error < 0)
            return error;
    } else {
        MSDOS_I(inode)->i_start = 0;
        inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
    }
    inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
               & ~((loff_t)sbi->cluster_size - 1)) >> 9;
    MSDOS_I(inode)->i_logstart = 0;
    MSDOS_I(inode)->mmu_private = inode->i_size;

    fat_save_attrs(inode, ATTR_DIR);
    inode->i_mtime.tv_sec = inode->i_atime.tv_sec = inode->i_ctime.tv_sec = 0;
    inode->i_mtime.tv_nsec = inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = 0;
    set_nlink(inode, fat_subdirs(inode)+2);

    return 0;
}

/*
 * Read the super block of an MS-DOS FS.
 */
int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
           void (*setup)(struct super_block *))
{
    struct inode *root_inode = NULL, *fat_inode = NULL;
    struct inode *fsinfo_inode = NULL;
    struct buffer_head *bh;
    struct fat_boot_sector *b;
    struct msdos_sb_info *sbi;
    u16 logical_sector_size;
    u32 total_sectors, total_clusters, fat_clusters, rootdir_sectors;
    int debug;
    unsigned int media;
    long error;
    char buf[50];

    /*
     * GFP_KERNEL is ok here, because while we do hold the
     * supeblock lock, memory pressure can't call back into
     * the filesystem, since we're only just about to mount
     * it and have no inodes etc active!
     */
    sbi = kzalloc(sizeof(struct msdos_sb_info), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;
    sb->s_fs_info = sbi;

    sb->s_flags |= MS_NODIRATIME;
    sb->s_magic = MSDOS_SUPER_MAGIC;
    sb->s_op = &fat_sops;
    sb->s_export_op = &fat_export_ops;
    ratelimit_state_init(&sbi->ratelimit, DEFAULT_RATELIMIT_INTERVAL,
                 DEFAULT_RATELIMIT_BURST);

    error = parse_options(sb, data, isvfat, silent, &debug, &sbi->options);
    if (error)
        goto out_fail;

    setup(sb); /* flavour-specific stuff that needs options */

    error = -EIO;
    sb_min_blocksize(sb, 512);
    bh = sb_bread(sb, 0);
    if (bh == NULL) {
        fat_msg(sb, KERN_ERR, "unable to read boot sector");
        goto out_fail;
    }

    b = (struct fat_boot_sector *) bh->b_data;
    if (!b->reserved) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "bogus number of reserved sectors");
        brelse(bh);
        goto out_invalid;
    }
    if (!b->fats) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "bogus number of FAT structure");
        brelse(bh);
        goto out_invalid;
    }

    /*
     * Earlier we checked here that b->secs_track and b->head are nonzero,
     * but it turns out valid FAT filesystems can have zero there.
     */

    media = b->media;
    if (!fat_valid_media(media)) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "invalid media value (0x%02x)",
                   media);
        brelse(bh);
        goto out_invalid;
    }
    logical_sector_size = get_unaligned_le16(&b->sector_size);
    if (!is_power_of_2(logical_sector_size)
        || (logical_sector_size < 512)
        || (logical_sector_size > 4096)) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "bogus logical sector size %u",
                   logical_sector_size);
        brelse(bh);
        goto out_invalid;
    }
    sbi->sec_per_clus = b->sec_per_clus;
    if (!is_power_of_2(sbi->sec_per_clus)) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "bogus sectors per cluster %u",
                   sbi->sec_per_clus);
        brelse(bh);
        goto out_invalid;
    }

    if (logical_sector_size < sb->s_blocksize) {
        fat_msg(sb, KERN_ERR, "logical sector size too small for device"
               " (logical sector size = %u)", logical_sector_size);
        brelse(bh);
        goto out_fail;
    }
    if (logical_sector_size > sb->s_blocksize) {
        brelse(bh);

        if (!sb_set_blocksize(sb, logical_sector_size)) {
            fat_msg(sb, KERN_ERR, "unable to set blocksize %u",
                   logical_sector_size);
            goto out_fail;
        }
        bh = sb_bread(sb, 0);
        if (bh == NULL) {
            fat_msg(sb, KERN_ERR, "unable to read boot sector"
                   " (logical sector size = %lu)",
                   sb->s_blocksize);
            goto out_fail;
        }
        b = (struct fat_boot_sector *) bh->b_data;
    }

    mutex_init(&sbi->s_lock);
    sbi->cluster_size = sb->s_blocksize * sbi->sec_per_clus;
    sbi->cluster_bits = ffs(sbi->cluster_size) - 1;
    sbi->fats = b->fats;
    sbi->fat_bits = 0;      /* Don't know yet */
    sbi->fat_start = le16_to_cpu(b->reserved);
    sbi->fat_length = le16_to_cpu(b->fat_length);
    sbi->root_cluster = 0;
    sbi->free_clusters = -1;    /* Don't know yet */
    sbi->free_clus_valid = 0;
    sbi->prev_free = FAT_START_ENT;
    sb->s_maxbytes = 0xffffffff;

    if (!sbi->fat_length && b->fat32_length) {
        struct fat_boot_fsinfo *fsinfo;
        struct buffer_head *fsinfo_bh;

        /* Must be FAT32 */
        sbi->fat_bits = 32;
        sbi->fat_length = le32_to_cpu(b->fat32_length);
        sbi->root_cluster = le32_to_cpu(b->root_cluster);

        /* MC - if info_sector is 0, don't multiply by 0 */
        sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
        if (sbi->fsinfo_sector == 0)
            sbi->fsinfo_sector = 1;

        fsinfo_bh = sb_bread(sb, sbi->fsinfo_sector);
        if (fsinfo_bh == NULL) {
            fat_msg(sb, KERN_ERR, "bread failed, FSINFO block"
                   " (sector = %lu)", sbi->fsinfo_sector);
            brelse(bh);
            goto out_fail;
        }

        fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
        if (!IS_FSINFO(fsinfo)) {
            fat_msg(sb, KERN_WARNING, "Invalid FSINFO signature: "
                   "0x%08x, 0x%08x (sector = %lu)",
                   le32_to_cpu(fsinfo->signature1),
                   le32_to_cpu(fsinfo->signature2),
                   sbi->fsinfo_sector);
        } else {
            if (sbi->options.usefree)
                sbi->free_clus_valid = 1;
            sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
            sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
        }

        brelse(fsinfo_bh);
    }

    sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
    sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;

    sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
    sbi->dir_entries = get_unaligned_le16(&b->dir_entries);
    if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "bogus directroy-entries per block"
                   " (%u)", sbi->dir_entries);
        brelse(bh);
        goto out_invalid;
    }

    rootdir_sectors = sbi->dir_entries
        * sizeof(struct msdos_dir_entry) / sb->s_blocksize;
    sbi->data_start = sbi->dir_start + rootdir_sectors;
    total_sectors = get_unaligned_le16(&b->sectors);
    if (total_sectors == 0)
        total_sectors = le32_to_cpu(b->total_sect);

    total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;

    if (sbi->fat_bits != 32)
        sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;

    /* check that FAT table does not overflow */
    fat_clusters = sbi->fat_length * sb->s_blocksize * 8 / sbi->fat_bits;
    total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
    if (total_clusters > MAX_FAT(sb)) {
        if (!silent)
            fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
                   total_clusters);
        brelse(bh);
        goto out_invalid;
    }

    sbi->max_cluster = total_clusters + FAT_START_ENT;
    /* check the free_clusters, it's not necessarily correct */
    if (sbi->free_clusters != -1 && sbi->free_clusters > total_clusters)
        sbi->free_clusters = -1;
    /* check the prev_free, it's not necessarily correct */
    sbi->prev_free %= sbi->max_cluster;
    if (sbi->prev_free < FAT_START_ENT)
        sbi->prev_free = FAT_START_ENT;

    brelse(bh);

    /* set up enough so that it can read an inode */
    fat_hash_init(sb);
    dir_hash_init(sb);
    fat_ent_access_init(sb);

    /*
     * The low byte of FAT's first entry must have same value with
     * media-field.  But in real world, too many devices is
     * writing wrong value.  So, removed that validity check.
     *
     * if (FAT_FIRST_ENT(sb, media) != first)
     */

    error = -EINVAL;
    sprintf(buf, "cp%d", sbi->options.codepage);
    sbi->nls_disk = load_nls(buf);
    if (!sbi->nls_disk) {
        fat_msg(sb, KERN_ERR, "codepage %s not found", buf);
        goto out_fail;
    }

    /* FIXME: utf8 is using iocharset for upper/lower conversion */
    if (sbi->options.isvfat) {
        sbi->nls_io = load_nls(sbi->options.iocharset);
        if (!sbi->nls_io) {
            fat_msg(sb, KERN_ERR, "IO charset %s not found",
                   sbi->options.iocharset);
            goto out_fail;
        }
    }

    error = -ENOMEM;
    fat_inode = new_inode(sb);
    if (!fat_inode)
        goto out_fail;
    MSDOS_I(fat_inode)->i_pos = 0;
    sbi->fat_inode = fat_inode;

    fsinfo_inode = new_inode(sb);
    if (!fsinfo_inode)
        goto out_fail;
    fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
    sbi->fsinfo_inode = fsinfo_inode;
    insert_inode_hash(fsinfo_inode);

    root_inode = new_inode(sb);
    if (!root_inode)
        goto out_fail;
    root_inode->i_ino = MSDOS_ROOT_INO;
    root_inode->i_version = 1;
    error = fat_read_root(root_inode);
    if (error < 0) {
        iput(root_inode);
        goto out_fail;
    }
    error = -ENOMEM;
    insert_inode_hash(root_inode);
    fat_attach(root_inode, 0);
    sb->s_root = d_make_root(root_inode);
    if (!sb->s_root) {
        fat_msg(sb, KERN_ERR, "get root inode failed");
        goto out_fail;
    }

    return 0;

out_invalid:
    error = -EINVAL;
    if (!silent)
        fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");

out_fail:
    if (fsinfo_inode)
        iput(fsinfo_inode);
    if (fat_inode)
        iput(fat_inode);
    unload_nls(sbi->nls_io);
    unload_nls(sbi->nls_disk);
    if (sbi->options.iocharset != fat_default_iocharset)
        kfree(sbi->options.iocharset);
    sb->s_fs_info = NULL;
    kfree(sbi);
    return error;
}

EXPORT_SYMBOL_GPL(fat_fill_super);

/*
 * helper function for fat_flush_inodes.  This writes both the inode
 * and the file data blocks, waiting for in flight data blocks before
 * the start of the call.  It does not wait for any io started
 * during the call
 */
static int writeback_inode(struct inode *inode)
{

    int ret;

    /* if we used wait=1, sync_inode_metadata waits for the io for the
    * inode to finish.  So wait=0 is sent down to sync_inode_metadata
    * and filemap_fdatawrite is used for the data blocks
    */
    ret = sync_inode_metadata(inode, 0);
    if (!ret)
        ret = filemap_fdatawrite(inode->i_mapping);
    return ret;
}

/*
 * write data and metadata corresponding to i1 and i2.  The io is
 * started but we do not wait for any of it to finish.
 *
 * filemap_flush is used for the block device, so if there is a dirty
 * page for a block already in flight, we will not wait and start the
 * io over again
 */
int fat_flush_inodes(struct super_block *sb, struct inode *i1, struct inode *i2)
{
    int ret = 0;
    if (!MSDOS_SB(sb)->options.flush)
        return 0;
    if (i1)
        ret = writeback_inode(i1);
    if (!ret && i2)
        ret = writeback_inode(i2);
    if (!ret) {
        struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
        ret = filemap_flush(mapping);
    }
    return ret;
}
EXPORT_SYMBOL_GPL(fat_flush_inodes);

static int __init init_fat_fs(void)
{
    int err;

    err = fat_cache_init();
    if (err)
        return err;

    err = fat_init_inodecache();
    if (err)
        goto failed;

    return 0;

failed:
    fat_cache_destroy();
    return err;
}

static void __exit exit_fat_fs(void)
{
    fat_cache_destroy();
    fat_destroy_inodecache();
}

module_init(init_fat_fs)
module_exit(exit_fat_fs)

MODULE_LICENSE("GPL");