1 files changed, 15 insertions, 11 deletions

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index c0b5b5c3373b..79bb0e73a65f 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -686,7 +686,7 @@ static void fat_set_state(struct super_block *sb,
 
 	b = (struct fat_boot_sector *) bh->b_data;
 
-	if (sbi->fat_bits == 32) {
+	if (is_fat32(sbi)) {
 		if (set)
 			b->fat32.state |= FAT_STATE_DIRTY;
 		else
@@ -1396,7 +1396,7 @@ static int fat_read_root(struct inode *inode)
 	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) {
+	if (is_fat32(sbi)) {
 		MSDOS_I(inode)->i_start = sbi->root_cluster;
 		error = fat_calc_dir_size(inode);
 		if (error < 0)
@@ -1423,7 +1423,7 @@ static unsigned long calc_fat_clusters(struct super_block *sb)
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
 	/* Divide first to avoid overflow */
-	if (sbi->fat_bits != 12) {
+	if (!is_fat12(sbi)) {
 		unsigned long ent_per_sec = sb->s_blocksize * 8 / sbi->fat_bits;
 		return ent_per_sec * sbi->fat_length;
 	}
@@ -1743,7 +1743,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	}
 
 	/* interpret volume ID as a little endian 32 bit integer */
-	if (sbi->fat_bits == 32)
+	if (is_fat32(sbi))
 		sbi->vol_id = bpb.fat32_vol_id;
 	else /* fat 16 or 12 */
 		sbi->vol_id = bpb.fat16_vol_id;
@@ -1769,11 +1769,11 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 
 	total_clusters = (total_sectors - sbi->data_start) / sbi->sec_per_clus;
 
-	if (sbi->fat_bits != 32)
+	if (!is_fat32(sbi))
 		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)
+	if (is_fat32(sbi))
 		sbi->dirty = bpb.fat32_state & FAT_STATE_DIRTY;
 	else /* fat 16 or 12 */
 		sbi->dirty = bpb.fat16_state & FAT_STATE_DIRTY;
@@ -1781,7 +1781,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	/* check that FAT table does not overflow */
 	fat_clusters = calc_fat_clusters(sb);
 	total_clusters = min(total_clusters, fat_clusters - FAT_START_ENT);
-	if (total_clusters > MAX_FAT(sb)) {
+	if (total_clusters > max_fat(sb)) {
 		if (!silent)
 			fat_msg(sb, KERN_ERR, "count of clusters too big (%u)",
 			       total_clusters);
@@ -1803,11 +1803,15 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
 	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.
+	 * The low byte of the first FAT entry must have the same value as
+	 * the media field of the boot sector. But in real world, too many
+	 * devices are writing wrong values. So, removed that validity check.
 	 *
-	 * if (FAT_FIRST_ENT(sb, media) != first)
+	 * The removed check compared the first FAT entry to a value dependent
+	 * on the media field like this:
+	 * == (0x0F00 | media), for FAT12
+	 * == (0XFF00 | media), for FAT16
+	 * == (0x0FFFFF | media), for FAT32
 	 */
 
 	error = -EINVAL;