From: Darrick J. Wong Date: Tue, 14 Oct 2014 06:35:49 +0000 (-0400) Subject: ext4: check s_chksum_driver when looking for bg csum presence X-Git-Tag: submit/tizen/20160422.055611~1^2~99^2~11^2~222 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9cf666834cffdb450b9b18f3e06c30493cb40ed2;p=sdk%2Femulator%2Femulator-kernel.git ext4: check s_chksum_driver when looking for bg csum presence 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 Signed-off-by: Theodore Ts'o Reviewed-by: Dmitry Monakhov Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index f57e9a795c5f..2a6830a7af33 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -2341,8 +2341,8 @@ 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 6686ce4a8773..608db5820740 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2019,6 +2019,10 @@ 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));