3.14-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Darrick J. Wong" <[email protected]> commit 813d32f91333e4c33d5a19b67167c4bae42dae75 upstream. 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 <[email protected]> Signed-off-by: Theodore Ts'o <[email protected]> Reviewed-by: Dmitry Monakhov <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/ext4/ext4.h | 4 ++-- fs/ext4/super.c | 4 ++++ 2 files changed, 6 insertions(+), 2 deletions(-) --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2341,8 +2341,8 @@ extern int ext4_register_li_request(stru 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) --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2019,6 +2019,10 @@ static __le16 ext4_group_desc_csum(struc } /* 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)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
