| From 813d32f91333e4c33d5a19b67167c4bae42dae75 Mon Sep 17 00:00:00 2001 |
| From: "Darrick J. Wong" <darrick.wong@oracle.com> |
| Date: Tue, 14 Oct 2014 02:35:49 -0400 |
| Subject: ext4: check s_chksum_driver when looking for bg csum presence |
| |
| From: "Darrick J. Wong" <darrick.wong@oracle.com> |
| |
| 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 <darrick.wong@oracle.com> |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| 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 |
| @@ -2333,8 +2333,8 @@ 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 |
| @@ -2025,6 +2025,10 @@ 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)); |