init android origin source code

1 files changed, 1619 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/fs/fat/inode.c b/ANDROID_3.4.5/fs/fat/inode.c
new file mode 100644
index 00000000..d403f76c
--- /dev/null
+++ b/ANDROID_3.4.5/fs/fat/inode.c
@@ -0,0 +1,1619 @@
+/*
+ *  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);
+}
+
+void fat_attach(struct inode *inode, loff_t i_pos)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+	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);
+}
+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(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 = 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;
+
+		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 = 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;
+	}
+	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);
+	end_writeback(inode);
+	fat_cache_inval_inode(inode);
+	fat_detach(inode);
+}
+
+static void fat_write_super(struct super_block *sb)
+{
+	lock_super(sb);
+	sb->s_dirt = 0;
+
+	if (!(sb->s_flags & MS_RDONLY))
+		fat_clusters_flush(sb);
+	unlock_super(sb);
+}
+
+static int fat_sync_fs(struct super_block *sb, int wait)
+{
+	int err = 0;
+
+	if (sb->s_dirt) {
+		lock_super(sb);
+		sb->s_dirt = 0;
+		err = fat_clusters_flush(sb);
+		unlock_super(sb);
+	}
+
+	return err;
+}
+
+static void fat_put_super(struct super_block *sb)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(sb);
+
+	if (sb->s_dirt)
+		fat_write_super(sb);
+
+	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);
+	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 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);
+	raw_entry->start = cpu_to_le16(MSDOS_I(inode)->i_logstart);
+	raw_entry->starthi = cpu_to_le16(MSDOS_I(inode)->i_logstart >> 16);
+	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)
+{
+	return __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
+}
+
+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,
+	.write_super	= fat_write_super,
+	.sync_fs	= fat_sync_fs,
+	.statfs		= fat_statfs,
+	.remount_fs	= fat_remount,
+
+	.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;
+	u32 *fh = fid->raw;
+
+	if (fh_len < 5 || fh_type != 3)
+		return NULL;
+
+	inode = ilookup(sb, fh[0]);
+	if (!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;
+		}
+	}
+
+	/*
+	 * For now, do nothing if the inode is not found.
+	 *
+	 * What we could do is:
+	 *
+	 *	- follow the file starting at fh[4], and record the ".." entry,
+	 *	  and the name of the fh[2] entry.
+	 *	- then 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 we are totally out
+	 * of luck.  But all that is for another day
+	 */
+	return d_obtain_alias(inode);
+}
+
+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) {
+		*lenp = 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 super_block *sb = child->d_sb;
+	struct buffer_head *bh;
+	struct msdos_dir_entry *de;
+	loff_t i_pos;
+	struct dentry *parent;
+	struct inode *inode;
+	int err;
+
+	lock_super(sb);
+
+	err = fat_get_dotdot_entry(child->d_inode, &bh, &de, &i_pos);
+	if (err) {
+		parent = ERR_PTR(err);
+		goto out;
+	}
+	inode = fat_build_inode(sb, de, i_pos);
+	brelse(bh);
+
+	parent = d_obtain_alias(inode);
+out:
+	unlock_super(sb);
+
+	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 dentry *root)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(root->d_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 (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->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_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_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->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 = 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_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;
+
+		/* 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 buffer_head *bh;
+	struct fat_boot_sector *b;
+	struct fat_boot_bsx *bsx;
+	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;
+	}
+
+	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;
+		}
+
+		bsx = (struct fat_boot_bsx *)(bh->b_data + FAT32_BSX_OFFSET);
+
+		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);
+	} else {
+		bsx = (struct fat_boot_bsx *)(bh->b_data + FAT16_BSX_OFFSET);
+	}
+
+	/* interpret volume ID as a little endian 32 bit integer */
+	sbi->vol_id = (((u32)bsx->vol_id[0]) | ((u32)bsx->vol_id[1] << 8) |
+		((u32)bsx->vol_id[2] << 16) | ((u32)bsx->vol_id[3] << 24));
+
+	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);
+	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;
+	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);
+	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 (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;
+	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");