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authorDarrick J. Wong <darrick.wong@oracle.com>2014-10-14 02:35:49 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-10-14 02:35:49 -0400
commit813d32f91333e4c33d5a19b67167c4bae42dae75 (patch)
tree09e1183d369c6b42a6fc3edcb73017ff54aa8a36 /fs/ext4
parentaef4885ae14f1df75b58395c5314d71f613d26d9 (diff)
ext4: check s_chksum_driver when looking for bg csum presence
Convert the ext4_has_group_desc_csum predicate to look for a checksum driver instead of the metadata_csum flag and change the bg checksum calculation function to look for GDT_CSUM before taking the crc16 path. Without this patch, if we mount with ^uninit_bg,^metadata_csum and later metadata_csum gets turned on by accident, the block group checksum functions will incorrectly assume that checksumming is enabled (metadata_csum) but that crc16 should be used (!s_chksum_driver). This is totally wrong, so fix the predicate and the checksum formula selection. (Granted, if the metadata_csum feature bit gets enabled on a live FS then something underhanded is going on, but we could at least avoid writing garbage into the on-disk fields.) Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/ext4.h4
-rw-r--r--fs/ext4/super.c4
2 files changed, 6 insertions, 2 deletions
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1483d9c6061f..c55a1faaed58 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2333,8 +2333,8 @@ extern int ext4_register_li_request(struct super_block *sb,
static inline int ext4_has_group_desc_csum(struct super_block *sb)
{
return EXT4_HAS_RO_COMPAT_FEATURE(sb,
- EXT4_FEATURE_RO_COMPAT_GDT_CSUM |
- EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
+ EXT4_FEATURE_RO_COMPAT_GDT_CSUM) ||
+ (EXT4_SB(sb)->s_chksum_driver != NULL);
}
static inline int ext4_has_metadata_csum(struct super_block *sb)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5afe42db303c..e96b6ecc8d34 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2005,6 +2005,10 @@ static __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
}
/* old crc16 code */
+ if (!(sbi->s_es->s_feature_ro_compat &
+ cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)))
+ return 0;
+
offset = offsetof(struct ext4_group_desc, bg_checksum);
crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));