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inode.c

/*
 *  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/smp_lock.h>
#include <linux/seq_file.h>
#include <linux/msdos_fs.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 <asm/unaligned.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);
      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_panic(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);
      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 int fat_write_begin(struct file *file, struct address_space *mapping,
                  loff_t pos, unsigned len, unsigned flags,
                  struct page **pagep, void **fsdata)
{
      *pagep = NULL;
      return cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
                        fat_get_block,
                        &MSDOS_I(mapping->host)->mmu_private);
}

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 < 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 inode *inode = file->f_mapping->host;

      if (rw == WRITE) {
            /*
             * FIXME: blockdev_direct_IO() doesn't use ->prepare_write(),
             * 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().
       */
      return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
                          offset, nr_segs, fat_get_block, NULL);
}

static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
{
      return generic_block_bmap(mapping, block, fat_get_block);
}

static const struct address_space_operations fat_aops = {
      .readpage   = fat_readpage,
      .readpages  = fat_readpages,
      .writepage  = fat_writepage,
      .writepages = fat_writepages,
      .sync_page  = block_sync_page,
      .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_clear_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(struct super_block *sb, loff_t i_pos)
{
      unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
      tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS * 2);
      return tmp & FAT_HASH_MASK;
}

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

      spin_lock(&sbi->inode_hash_lock);
      MSDOS_I(inode)->i_pos = i_pos;
      hlist_add_head(&MSDOS_I(inode)->i_fat_hash,
                  sbi->inode_hashtable + fat_hash(sb, i_pos));
      spin_unlock(&sbi->inode_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);
}

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(sb, 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 = MSDOS_MKMODE(de->attr,
                  S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
            inode->i_op = sbi->dir_ops;
            inode->i_fop = &fat_dir_operations;

            MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
            if (sbi->fat_bits == 32)
                  MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);

            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;

            inode->i_nlink = fat_subdirs(inode);
      } else { /* not a directory */
            inode->i_generation |= 1;
            inode->i_mode = MSDOS_MKMODE(de->attr,
                ((sbi->options.showexec && !is_exec(de->name + 8))
                  ? S_IRUGO|S_IWUGO : S_IRWXUGO)
                & ~sbi->options.fs_fmask) | S_IFREG;
            MSDOS_I(inode)->i_start = le16_to_cpu(de->start);
            if (sbi->fat_bits == 32)
                  MSDOS_I(inode)->i_start |= (le16_to_cpu(de->starthi) << 16);

            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;
      }
      MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
      inode->i_blocks = ((inode->i_size + (sbi->cluster_size - 1))
                     & ~((loff_t)sbi->cluster_size - 1)) >> 9;
      inode->i_mtime.tv_sec =
            date_dos2unix(le16_to_cpu(de->time), le16_to_cpu(de->date));
      inode->i_mtime.tv_nsec = 0;
      if (sbi->options.isvfat) {
            int secs = de->ctime_cs / 100;
            int csecs = de->ctime_cs % 100;
            inode->i_ctime.tv_sec  =
                  date_dos2unix(le16_to_cpu(de->ctime),
                              le16_to_cpu(de->cdate)) + secs;
            inode->i_ctime.tv_nsec = csecs * 10000000;
            inode->i_atime.tv_sec =
                  date_dos2unix(0, le16_to_cpu(de->adate));
            inode->i_atime.tv_nsec = 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_delete_inode(struct inode *inode)
{
      truncate_inode_pages(&inode->i_data, 0);

      if (!is_bad_inode(inode)) {
            inode->i_size = 0;
            fat_truncate(inode);
      }
      clear_inode(inode);
}

static void fat_clear_inode(struct inode *inode)
{
      struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);

      if (is_bad_inode(inode))
            return;
      lock_kernel();
      spin_lock(&sbi->inode_hash_lock);
      fat_cache_inval_inode(inode);
      hlist_del_init(&MSDOS_I(inode)->i_fat_hash);
      spin_unlock(&sbi->inode_hash_lock);
      unlock_kernel();
}

static void fat_write_super(struct super_block *sb)
{
      sb->s_dirt = 0;

      if (!(sb->s_flags & MS_RDONLY))
            fat_clusters_flush(sb);
}

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

      if (sbi->nls_disk) {
            unload_nls(sbi->nls_disk);
            sbi->nls_disk = NULL;
            sbi->options.codepage = fat_default_codepage;
      }
      if (sbi->nls_io) {
            unload_nls(sbi->nls_io);
            sbi->nls_io = NULL;
      }
      if (sbi->options.iocharset != fat_default_iocharset) {
            kfree(sbi->options.iocharset);
            sbi->options.iocharset = fat_default_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_KERNEL);
      if (!ei)
            return NULL;
      return &ei->vfs_inode;
}

static void fat_destroy_inode(struct inode *inode)
{
      kmem_cache_free(fat_inode_cachep, MSDOS_I(inode));
}

static void init_once(struct kmem_cache *cachep, 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);
      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)
{
      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 msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);

      /* If the count of free cluster is still unknown, counts it here. */
      if (sbi->free_clusters == -1) {
            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_namelen = sbi->options.isvfat ? 260 : 12;

      return 0;
}

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 = 0;

retry:
      i_pos = MSDOS_I(inode)->i_pos;
      if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
            return 0;

      lock_kernel();
      bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);
      if (!bh) {
            printk(KERN_ERR "FAT: unable to read inode block "
                   "for updating (i_pos %lld)\n", i_pos);
            err = -EIO;
            goto out;
      }
      spin_lock(&sbi->inode_hash_lock);
      if (i_pos != MSDOS_I(inode)->i_pos) {
            spin_unlock(&sbi->inode_hash_lock);
            brelse(bh);
            unlock_kernel();
            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_attr(inode);
      raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
      raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
      fat_date_unix2dos(inode->i_mtime.tv_sec, &raw_entry->time, &raw_entry->date);
      if (sbi->options.isvfat) {
            __le16 atime;
            fat_date_unix2dos(inode->i_ctime.tv_sec,&raw_entry->ctime,&raw_entry->cdate);
            fat_date_unix2dos(inode->i_atime.tv_sec,&atime,&raw_entry->adate);
            raw_entry->ctime_cs = (inode->i_ctime.tv_sec & 1) * 100 +
                  inode->i_ctime.tv_nsec / 10000000;
      }
      spin_unlock(&sbi->inode_hash_lock);
      mark_buffer_dirty(bh);
      if (wait)
            err = sync_dirty_buffer(bh);
      brelse(bh);
out:
      unlock_kernel();
      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 vfsmount *mnt);
static const struct super_operations fat_sops = {
      .alloc_inode      = fat_alloc_inode,
      .destroy_inode    = fat_destroy_inode,
      .write_inode      = fat_write_inode,
      .delete_inode     = fat_delete_inode,
      .put_super  = fat_put_super,
      .write_super      = fat_write_super,
      .statfs           = fat_statfs,
      .clear_inode      = fat_clear_inode,
      .remount_fs = fat_remount,

      .read_inode = make_bad_inode,

      .show_options     = fat_show_options,
};

/*
 * a FAT file handle with fhtype 3 is
 *  0/  i_ino - for fast, reliable lookup if still in the cache
 *  1/  i_generation - to see if i_ino is still valid
 *          bit 0 == 0 iff directory
 *  2/  i_pos(8-39) - if ino has changed, but still in cache
 *  3/  i_pos(4-7)|i_logstart - to semi-verify inode found at i_pos
 *  4/  i_pos(0-3)|parent->i_logstart - maybe used to hunt for the file on disc
 *
 * Hack for NFSv2: Maximum FAT entry number is 28bits and maximum
 * i_pos is 40bits (blocknr(32) + dir offset(8)), so two 4bits
 * of i_logstart is used to store the directory entry offset.
 */

static struct dentry *fat_fh_to_dentry(struct super_block *sb,
            struct fid *fid, int fh_len, int fh_type)
{
      struct inode *inode = NULL;
      struct dentry *result;
      u32 *fh = fid->raw;

      if (fh_len < 5 || fh_type != 3)
            return NULL;

      inode = iget(sb, fh[0]);
      if (!inode || is_bad_inode(inode) || inode->i_generation != fh[1]) {
            if (inode)
                  iput(inode);
            inode = NULL;
      }
      if (!inode) {
            loff_t i_pos;
            int i_logstart = fh[3] & 0x0fffffff;

            i_pos = (loff_t)fh[2] << 8;
            i_pos |= ((fh[3] >> 24) & 0xf0) | (fh[4] >> 28);

            /* try 2 - see if i_pos is in F-d-c
             * require i_logstart to be the same
             * Will fail if you truncate and then re-write
             */

            inode = fat_iget(sb, i_pos);
            if (inode && MSDOS_I(inode)->i_logstart != i_logstart) {
                  iput(inode);
                  inode = NULL;
            }
      }
      if (!inode) {
            /* For now, do nothing
             * What we could do is:
             * follow the file starting at fh[4], and record
             * the ".." entry, and the name of the fh[2] entry.
             * The follow the ".." file finding the next step up.
             * This way we build a path to the root of
             * the tree. If this works, we lookup the path and so
             * get this inode into the cache.
             * Finally try the fat_iget lookup again
             * If that fails, then weare totally out of luck
             * But all that is for another day
             */
      }
      if (!inode)
            return ERR_PTR(-ESTALE);


      /* now to find a dentry.
       * If possible, get a well-connected one
       */
      result = d_alloc_anon(inode);
      if (result == NULL) {
            iput(inode);
            return ERR_PTR(-ENOMEM);
      }
      result->d_op = sb->s_root->d_op;
      return result;
}

static int
fat_encode_fh(struct dentry *de, __u32 *fh, int *lenp, int connectable)
{
      int len = *lenp;
      struct inode *inode =  de->d_inode;
      u32 ipos_h, ipos_m, ipos_l;

      if (len < 5)
            return 255; /* no room */

      ipos_h = MSDOS_I(inode)->i_pos >> 8;
      ipos_m = (MSDOS_I(inode)->i_pos & 0xf0) << 24;
      ipos_l = (MSDOS_I(inode)->i_pos & 0x0f) << 28;
      *lenp = 5;
      fh[0] = inode->i_ino;
      fh[1] = inode->i_generation;
      fh[2] = ipos_h;
      fh[3] = ipos_m | MSDOS_I(inode)->i_logstart;
      spin_lock(&de->d_lock);
      fh[4] = ipos_l | MSDOS_I(de->d_parent->d_inode)->i_logstart;
      spin_unlock(&de->d_lock);
      return 3;
}

static struct dentry *fat_get_parent(struct dentry *child)
{
      struct buffer_head *bh;
      struct msdos_dir_entry *de;
      loff_t i_pos;
      struct dentry *parent;
      struct inode *inode;
      int err;

      lock_kernel();

      err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
      if (err) {
            parent = ERR_PTR(err);
            goto out;
      }
      inode = fat_build_inode(child->d_sb, de, i_pos);
      brelse(bh);
      if (IS_ERR(inode)) {
            parent = ERR_PTR(PTR_ERR(inode));
            goto out;
      }
      parent = d_alloc_anon(inode);
      if (!parent) {
            iput(inode);
            parent = ERR_PTR(-ENOMEM);
      }
out:
      unlock_kernel();

      return parent;
}

static const struct export_operations fat_export_ops = {
      .encode_fh  = fat_encode_fh,
      .fh_to_dentry     = fat_fh_to_dentry,
      .get_parent = fat_get_parent,
};

static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
{
      struct msdos_sb_info *sbi = MSDOS_SB(mnt->mnt_sb);
      struct fat_mount_options *opts = &sbi->options;
      int isvfat = opts->isvfat;

      if (opts->fs_uid != 0)
            seq_printf(m, ",uid=%u", opts->fs_uid);
      if (opts->fs_gid != 0)
            seq_printf(m, ",gid=%u", opts->fs_gid);
      seq_printf(m, ",fmask=%04o", opts->fs_fmask);
      seq_printf(m, ",dmask=%04o", opts->fs_dmask);
      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->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");
      }

      return 0;
}

enum {
      Opt_check_n, Opt_check_r, Opt_check_s, Opt_uid, Opt_gid,
      Opt_umask, Opt_dmask, Opt_fmask, 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_obsolate, Opt_flush, Opt_err,
};

static 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_codepage, "codepage=%u"},
      {Opt_usefree, "usefree"},
      {Opt_nocase, "nocase"},
      {Opt_quiet, "quiet"},
      {Opt_showexec, "showexec"},
      {Opt_debug, "debug"},
      {Opt_immutable, "sys_immutable"},
      {Opt_obsolate, "conv=binary"},
      {Opt_obsolate, "conv=text"},
      {Opt_obsolate, "conv=auto"},
      {Opt_obsolate, "conv=b"},
      {Opt_obsolate, "conv=t"},
      {Opt_obsolate, "conv=a"},
      {Opt_obsolate, "fat=%u"},
      {Opt_obsolate, "blocksize=%u"},
      {Opt_obsolate, "cvf_format=%20s"},
      {Opt_obsolate, "cvf_options=%100s"},
      {Opt_obsolate, "posix"},
      {Opt_flush, "flush"},
      {Opt_err, NULL},
};
static match_table_t msdos_tokens = {
      {Opt_nodots, "nodots"},
      {Opt_nodots, "dotsOK=no"},
      {Opt_dots, "dots"},
      {Opt_dots, "dotsOK=yes"},
      {Opt_err, NULL}
};
static 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_err, NULL}
};

static int parse_options(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->fs->umask;
      opts->codepage = fat_default_codepage;
      opts->iocharset = fat_default_iocharset;
      if (is_vfat)
            opts->shortname = VFAT_SFN_DISPLAY_LOWER|VFAT_SFN_CREATE_WIN95;
      else
            opts->shortname = 0;
      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;
      *debug = 0;

      if (!options)
            return 0;

      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 = option;
                  break;
            case Opt_gid:
                  if (match_int(&args[0], &option))
                        return 0;
                  opts->fs_gid = option;
                  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_codepage:
                  if (match_int(&args[0], &option))
                        return 0;
                  opts->codepage = option;
                  break;
            case Opt_flush:
                  opts->flush = 1;
                  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;

            /* obsolete mount options */
            case Opt_obsolate:
                  printk(KERN_INFO "FAT: \"%s\" option is obsolete, "
                         "not supported now\n", p);
                  break;
            /* unknown option */
            default:
                  if (!silent) {
                        printk(KERN_ERR
                               "FAT: Unrecognized mount option \"%s\" "
                               "or missing value\n", p);
                  }
                  return -EINVAL;
            }
      }
      /* UTF-8 doesn't provide FAT semantics */
      if (!strcmp(opts->iocharset, "utf8")) {
            printk(KERN_ERR "FAT: utf8 is not a recommended IO charset"
                   " for FAT filesystems, filesystem will be case sensitive!\n");
      }

      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 = (S_IRWXUGO & ~sbi->options.fs_dmask) | S_IFDIR;
      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;

      MSDOS_I(inode)->i_attrs = ATTR_NONE;
      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;
      inode->i_nlink = 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,
               const struct inode_operations *fs_dir_inode_ops, int isvfat)
{
      struct inode *root_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];

      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;
      sbi->dir_ops = fs_dir_inode_ops;

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

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

      b = (struct fat_boot_sector *) bh->b_data;
      if (!b->reserved) {
            if (!silent)
                  printk(KERN_ERR "FAT: bogus number of reserved sectors\n");
            brelse(bh);
            goto out_invalid;
      }
      if (!b->fats) {
            if (!silent)
                  printk(KERN_ERR "FAT: bogus number of FAT structure\n");
            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)
                  printk(KERN_ERR "FAT: invalid media value (0x%02x)\n",
                         media);
            brelse(bh);
            goto out_invalid;
      }
      logical_sector_size =
            le16_to_cpu(get_unaligned((__le16 *)&b->sector_size));
      if (!is_power_of_2(logical_sector_size)
          || (logical_sector_size < 512)
          || (PAGE_CACHE_SIZE < logical_sector_size)) {
            if (!silent)
                  printk(KERN_ERR "FAT: bogus logical sector size %u\n",
                         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)
                  printk(KERN_ERR "FAT: bogus sectors per cluster %u\n",
                         sbi->sec_per_clus);
            brelse(bh);
            goto out_invalid;
      }

      if (logical_sector_size < sb->s_blocksize) {
            printk(KERN_ERR "FAT: logical sector size too small for device"
                   " (logical sector size = %u)\n", 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)) {
                  printk(KERN_ERR "FAT: unable to set blocksize %u\n",
                         logical_sector_size);
                  goto out_fail;
            }
            bh = sb_bread(sb, 0);
            if (bh == NULL) {
                  printk(KERN_ERR "FAT: unable to read boot sector"
                         " (logical sector size = %lu)\n",
                         sb->s_blocksize);
                  goto out_fail;
            }
            b = (struct fat_boot_sector *) bh->b_data;
      }

      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->prev_free = FAT_START_ENT;

      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);

            sb->s_maxbytes = 0xffffffff;

            /* 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) {
                  printk(KERN_ERR "FAT: bread failed, FSINFO block"
                         " (sector = %lu)\n", sbi->fsinfo_sector);
                  brelse(bh);
                  goto out_fail;
            }

            fsinfo = (struct fat_boot_fsinfo *)fsinfo_bh->b_data;
            if (!IS_FSINFO(fsinfo)) {
                  printk(KERN_WARNING
                         "FAT: Did not find valid FSINFO signature.\n"
                         "     Found signature1 0x%08x signature2 0x%08x"
                         " (sector = %lu)\n",
                         le32_to_cpu(fsinfo->signature1),
                         le32_to_cpu(fsinfo->signature2),
                         sbi->fsinfo_sector);
            } else {
                  if (sbi->options.usefree)
                        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 =
            le16_to_cpu(get_unaligned((__le16 *)&b->dir_entries));
      if (sbi->dir_entries & (sbi->dir_per_block - 1)) {
            if (!silent)
                  printk(KERN_ERR "FAT: bogus directroy-entries per block"
                         " (%u)\n", 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 = le16_to_cpu(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)
                  printk(KERN_ERR "FAT: count of clusters too big (%u)\n",
                         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);
      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) {
            printk(KERN_ERR "FAT: codepage %s not found\n", 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) {
                  printk(KERN_ERR "FAT: IO charset %s not found\n",
                         sbi->options.iocharset);
                  goto out_fail;
            }
      }

      error = -ENOMEM;
      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)
            goto out_fail;
      error = -ENOMEM;
      insert_inode_hash(root_inode);
      sb->s_root = d_alloc_root(root_inode);
      if (!sb->s_root) {
            printk(KERN_ERR "FAT: get root inode failed\n");
            goto out_fail;
      }

      return 0;

out_invalid:
      error = -EINVAL;
      if (!silent)
            printk(KERN_INFO "VFS: Can't find a valid FAT filesystem"
                   " on dev %s.\n", sb->s_id);

out_fail:
      if (root_inode)
            iput(root_inode);
      if (sbi->nls_io)
            unload_nls(sbi->nls_io);
      if (sbi->nls_disk)
            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;
      struct address_space *mapping = inode->i_mapping;
      struct writeback_control wbc = {
             .sync_mode = WB_SYNC_NONE,
            .nr_to_write = 0,
      };
      /* if we used WB_SYNC_ALL, sync_inode waits for the io for the
      * inode to finish.  So WB_SYNC_NONE is sent down to sync_inode
      * and filemap_fdatawrite is used for the data blocks
      */
      ret = sync_inode(inode, &wbc);
      if (!ret)
             ret = filemap_fdatawrite(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");

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