ext4: Replace open coded mdata csum feature to helper function

Besides the fact that this replacement improves code readability
it also protects from errors caused direct EXT4_S(sb)->s_es manipulation
which may result attempt to use uninitialized  csum machinery.

#Testcase_BEGIN
IMG=/dev/ram0
MNT=/mnt
mkfs.ext4 $IMG
mount $IMG $MNT
#Enable feature directly on disk, on mounted fs
tune2fs -O metadata_csum  $IMG
# Provoke metadata update, likey result in OOPS
touch $MNT/test
umount $MNT
#Testcase_END

# Replacement script
@@
expression E;
@@
- EXT4_HAS_RO_COMPAT_FEATURE(E, EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)
+ ext4_has_metadata_csum(E)

https://bugzilla.kernel.org/show_bug.cgi?id=82201

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

1 files changed, 5 insertions, 10 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a0811cc00c91..5afe42db303c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -140,8 +140,7 @@ static __le32 ext4_superblock_csum(struct super_block *sb,
 static int ext4_superblock_csum_verify(struct super_block *sb,
                                        struct ext4_super_block *es)
 {
-        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
-                                       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+        if (!ext4_has_metadata_csum(sb))
                 return 1;
 
         return es->s_checksum == ext4_superblock_csum(sb, es);
@@ -151,8 +150,7 @@ void ext4_superblock_csum_set(struct super_block *sb)
 {
         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 
-        if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
-                EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+        if (!ext4_has_metadata_csum(sb))
                 return;
 
         es->s_checksum = ext4_superblock_csum(sb, es);
@@ -1989,8 +1987,7 @@ static __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
         __u16 crc = 0;
         __le32 le_group = cpu_to_le32(block_group);
 
-        if ((sbi->s_es->s_feature_ro_compat &
-             cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))) {
+        if (ext4_has_metadata_csum(sbi->s_sb)) {
                 /* Use new metadata_csum algorithm */
                 __le16 save_csum;
                 __u32 csum32;
@@ -3199,8 +3196,7 @@ static int set_journal_csum_feature_set(struct super_block *sb)
         int compat, incompat;
         struct ext4_sb_info *sbi = EXT4_SB(sb);
 
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
-                                       EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {
+        if (ext4_has_metadata_csum(sb)) {
                 /* journal checksum v3 */
                 compat = 0;
                 incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
@@ -3508,8 +3504,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         }
 
         /* Precompute checksum seed for all metadata */
-        if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
-                        EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+        if (ext4_has_metadata_csum(sb))
                 sbi->s_csum_seed = ext4_chksum(sbi, ~0, es->s_uuid,
                                                sizeof(es->s_uuid));