fat: new inline functions to determine the FAT variant (32, 16 or 12)

This patch introduces 3 new inline functions - is_fat12, is_fat16 and
is_fat32, and replaces every occurrence in the code in which the FS
variant (whether this is FAT12, FAT16 or FAT32) was previously checked
using msdos_sb_info->fat_bits.

Link: http://lkml.kernel.org/r/1544990640-11604-4-git-send-email-carmeli.tamir@gmail.com
Signed-off-by: Carmeli Tamir <carmeli.tamir@gmail.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fat/cache.c

@@ -363,7 +363,7 @@ int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
 
 	*phys = 0;
 	*mapped_blocks = 0;
-	if ((sbi->fat_bits != 32) && (inode->i_ino == MSDOS_ROOT_INO)) {
+	if (!is_fat32(sbi) && (inode->i_ino == MSDOS_ROOT_INO)) {
 		if (sector < (sbi->dir_entries >> sbi->dir_per_block_bits)) {
 			*phys = sector + sbi->dir_start;
 			*mapped_blocks = 1;

fs/fat/dir.c

@@ -57,7 +57,7 @@ static inline void fat_dir_readahead(struct inode *dir, sector_t iblock,
 	if ((iblock & (sbi->sec_per_clus - 1)) || sbi->sec_per_clus == 1)
 		return;
 	/* root dir of FAT12/FAT16 */
-	if ((sbi->fat_bits != 32) && (dir->i_ino == MSDOS_ROOT_INO))
+	if (!is_fat32(sbi) && (dir->i_ino == MSDOS_ROOT_INO))
 		return;
 
 	bh = sb_find_get_block(sb, phys);
@@ -1313,7 +1313,7 @@ int fat_add_entries(struct inode *dir, void *slots, int nr_slots,
 		}
 	}
 	if (dir->i_ino == MSDOS_ROOT_INO) {
-		if (sbi->fat_bits != 32)
+		if (!is_fat32(sbi))
 			goto error;
 	} else if (MSDOS_I(dir)->i_start == 0) {
 		fat_msg(sb, KERN_ERR, "Corrupted directory (i_pos %lld)",

fs/fat/fat.h

@@ -142,13 +142,32 @@ static inline struct msdos_sb_info *MSDOS_SB(struct super_block *sb)
 	return sb->s_fs_info;
 }
 
+/*
+ * Functions that determine the variant of the FAT file system (i.e.,
+ * whether this is FAT12, FAT16 or FAT32.
+ */
+static inline bool is_fat12(const struct msdos_sb_info *sbi)
+{
+	return sbi->fat_bits == 12;
+}
+
+static inline bool is_fat16(const struct msdos_sb_info *sbi)
+{
+	return sbi->fat_bits == 16;
+}
+
+static inline bool is_fat32(const struct msdos_sb_info *sbi)
+{
+	return sbi->fat_bits == 32;
+}
+
 /* Maximum number of clusters */
 static inline u32 max_fat(struct super_block *sb)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
-	return sbi->fat_bits == 32 ? MAX_FAT32 :
+	return is_fat32(sbi) ? MAX_FAT32 :
-		sbi->fat_bits == 16 ? MAX_FAT16 : MAX_FAT12;
+		is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
 }
 
 static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
@@ -266,7 +285,7 @@ static inline int fat_get_start(const struct msdos_sb_info *sbi,
 				const struct msdos_dir_entry *de)
 {
 	int cluster = le16_to_cpu(de->start);
-	if (sbi->fat_bits == 32)
+	if (is_fat32(sbi))
 		cluster |= (le16_to_cpu(de->starthi) << 16);
 	return cluster;
 }

fs/fat/fatent.c

@@ -290,19 +290,17 @@ void fat_ent_access_init(struct super_block *sb)
 
 	mutex_init(&sbi->fat_lock);
 
-	switch (sbi->fat_bits) {
+	if (is_fat32(sbi)) {
-	case 32:
 		sbi->fatent_shift = 2;
 		sbi->fatent_ops = &fat32_ops;
-		break;
+	} else if (is_fat16(sbi)) {
-	case 16:
 		sbi->fatent_shift = 1;
 		sbi->fatent_ops = &fat16_ops;
-		break;
+	} else if (is_fat12(sbi)) {
-	case 12:
 		sbi->fatent_shift = -1;
 		sbi->fatent_ops = &fat12_ops;
-		break;
+	} else {
+		fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
 	}
 }
 
@@ -310,7 +308,7 @@ static void mark_fsinfo_dirty(struct super_block *sb)
 {
 	struct msdos_sb_info *sbi = MSDOS_SB(sb);
 
-	if (sb_rdonly(sb) || sbi->fat_bits != 32)
+	if (sb_rdonly(sb) || !is_fat32(sbi))
 		return;
 
 	__mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC);
@@ -327,7 +325,7 @@ static inline int fat_ent_update_ptr(struct super_block *sb,
 	/* Is this fatent's blocks including this entry? */
 	if (!fatent->nr_bhs || bhs[0]->b_blocknr != blocknr)
 		return 0;
-	if (sbi->fat_bits == 12) {
+	if (is_fat12(sbi)) {
 		if ((offset + 1) < sb->s_blocksize) {
 			/* This entry is on bhs[0]. */
 			if (fatent->nr_bhs == 2) {

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;

fs/fat/misc.c

@@ -64,7 +64,7 @@ int fat_clusters_flush(struct super_block *sb)
 	struct buffer_head *bh;
 	struct fat_boot_fsinfo *fsinfo;
 
-	if (sbi->fat_bits != 32)
+	if (!is_fat32(sbi))
 		return 0;
 
 	bh = sb_bread(sb, sbi->fsinfo_sector);