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fat: new inline functions to determine the FAT variant (32, 16 or 12)
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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>
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Carmeli Tamir authored and Linus Torvalds committed Jan 4, 2019
1 parent d19dc01 commit 306790f
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Showing 6 changed files with 39 additions and 22 deletions.
2 changes: 1 addition & 1 deletion fs/fat/cache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
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4 changes: 2 additions & 2 deletions fs/fat/dir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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)",
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25 changes: 22 additions & 3 deletions fs/fat/fat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 :
sbi->fat_bits == 16 ? MAX_FAT16 : MAX_FAT12;
return is_fat32(sbi) ? MAX_FAT32 :
is_fat16(sbi) ? MAX_FAT16 : MAX_FAT12;
}

static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
Expand Down Expand Up @@ -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;
}
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16 changes: 7 additions & 9 deletions fs/fat/fatent.c
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Original file line number Diff line number Diff line change
Expand Up @@ -290,27 +290,25 @@ void fat_ent_access_init(struct super_block *sb)

mutex_init(&sbi->fat_lock);

switch (sbi->fat_bits) {
case 32:
if (is_fat32(sbi)) {
sbi->fatent_shift = 2;
sbi->fatent_ops = &fat32_ops;
break;
case 16:
} else if (is_fat16(sbi)) {
sbi->fatent_shift = 1;
sbi->fatent_ops = &fat16_ops;
break;
case 12:
} else if (is_fat12(sbi)) {
sbi->fatent_shift = -1;
sbi->fatent_ops = &fat12_ops;
break;
} else {
fat_fs_error(sb, "invalid FAT variant, %u bits", sbi->fat_bits);
}
}

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);
Expand All @@ -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) {
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12 changes: 6 additions & 6 deletions fs/fat/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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)
Expand All @@ -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;
}
Expand Down Expand Up @@ -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;
Expand All @@ -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;
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2 changes: 1 addition & 1 deletion fs/fat/misc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down

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