3 files changed, 74 insertions, 8 deletions

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 12701a567752..e9cc3f0d58e2 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -95,6 +95,8 @@ struct msdos_sb_info {
 
 	spinlock_t dir_hash_lock;
 	struct hlist_head dir_hashtable[FAT_HASH_SIZE];
+
+	unsigned int dirty;           /* fs state before mount */
 };
 
 #define FAT_CACHE_VALID	0	/* special case for valid cache */
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index f8f491677a4a..acf6e479b443 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -341,12 +341,11 @@ 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) {
+	hlist_for_each_entry(i, head, i_fat_hash) {
 		BUG_ON(i->vfs_inode.i_sb != sb);
 		if (i->i_pos != i_pos)
 			continue;
@@ -488,10 +487,59 @@ static void fat_evict_inode(struct inode *inode)
 	fat_detach(inode);
 }
 
+static void fat_set_state(struct super_block *sb,
+			unsigned int set, unsigned int force)
+{
+	struct buffer_head *bh;
+	struct fat_boot_sector *b;
+	struct msdos_sb_info *sbi = sb->s_fs_info;
+
+	/* do not change any thing if mounted read only */
+	if ((sb->s_flags & MS_RDONLY) && !force)
+		return;
+
+	/* do not change state if fs was dirty */
+	if (sbi->dirty) {
+		/* warn only on set (mount). */
+		if (set)
+			fat_msg(sb, KERN_WARNING, "Volume was not properly "
+				"unmounted. Some data may be corrupt. "
+				"Please run fsck.");
+		return;
+	}
+
+	bh = sb_bread(sb, 0);
+	if (bh == NULL) {
+		fat_msg(sb, KERN_ERR, "unable to read boot sector "
+			"to mark fs as dirty");
+		return;
+	}
+
+	b = (struct fat_boot_sector *) bh->b_data;
+
+	if (sbi->fat_bits == 32) {
+		if (set)
+			b->fat32.state |= FAT_STATE_DIRTY;
+		else
+			b->fat32.state &= ~FAT_STATE_DIRTY;
+	} else /* fat 16 and 12 */ {
+		if (set)
+			b->fat16.state |= FAT_STATE_DIRTY;
+		else
+			b->fat16.state &= ~FAT_STATE_DIRTY;
+	}
+
+	mark_buffer_dirty(bh);
+	sync_dirty_buffer(bh);
+	brelse(bh);
+}
+
 static void fat_put_super(struct super_block *sb)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
+	fat_set_state(sb, 0, 0);
+
 	iput(sbi->fsinfo_inode);
 	iput(sbi->fat_inode);
 
@@ -566,8 +614,18 @@ static void __exit fat_destroy_inodecache(void)
 
 static int fat_remount(struct super_block *sb, int *flags, char *data)
 {
+	int new_rdonly;
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 	*flags |= MS_NODIRATIME | (sbi->options.isvfat ? 0 : MS_NOATIME);
+
+	/* make sure we update state on remount. */
+	new_rdonly = *flags & MS_RDONLY;
+	if (new_rdonly != (sb->s_flags & MS_RDONLY)) {
+		if (new_rdonly)
+			fat_set_state(sb, 0, 0);
+		else
+			fat_set_state(sb, 1, 1);
+	}
 	return 0;
 }
 
@@ -1298,17 +1356,17 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	sbi->prev_free = FAT_START_ENT;
 	sb->s_maxbytes = 0xffffffff;
 
-	if (!sbi->fat_length && b->fat32_length) {
+	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);
+		sbi->fat_length = le32_to_cpu(b->fat32.length);
+		sbi->root_cluster = le32_to_cpu(b->fat32.root_cluster);
 
 		/* MC - if info_sector is 0, don't multiply by 0 */
-		sbi->fsinfo_sector = le16_to_cpu(b->info_sector);
+		sbi->fsinfo_sector = le16_to_cpu(b->fat32.info_sector);
 		if (sbi->fsinfo_sector == 0)
 			sbi->fsinfo_sector = 1;
 
@@ -1362,6 +1420,12 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	if (sbi->fat_bits != 32)
 		sbi->fat_bits = (total_clusters > MAX_FAT12) ? 16 : 12;
 
+	/* some OSes set FAT_STATE_DIRTY and clean it on unmount. */
+	if (sbi->fat_bits == 32)
+		sbi->dirty = b->fat32.state & FAT_STATE_DIRTY;
+	else /* fat 16 or 12 */
+		sbi->dirty = b->fat16.state & FAT_STATE_DIRTY;
+
 	/* 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);
@@ -1456,6 +1520,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 					"the device does not support discard");
 	}
 
+	fat_set_state(sb, 1, 0);
 	return 0;
 
 out_invalid:
diff --git a/fs/fat/nfs.c b/fs/fat/nfs.c
index ef4b5faba87b..499c10438ca2 100644
--- a/fs/fat/nfs.c
+++ b/fs/fat/nfs.c
@@ -21,13 +21,12 @@ static struct inode *fat_dget(struct super_block *sb, int i_logstart)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 	struct hlist_head *head;
-	struct hlist_node *_p;
 	struct msdos_inode_info *i;
 	struct inode *inode = NULL;
 
 	head = sbi->dir_hashtable + fat_dir_hash(i_logstart);
 	spin_lock(&sbi->dir_hash_lock);
-	hlist_for_each_entry(i, _p, head, i_dir_hash) {
+	hlist_for_each_entry(i, head, i_dir_hash) {
 		BUG_ON(i->vfs_inode.i_sb != sb);
 		if (i->i_logstart != i_logstart)
 			continue;