@@ -749,6 +749,11 @@ xfs_sb_verify(
* single bit error could clear the feature bit and unused parts of the
* superblock are supposed to be zero. Hence a non-null crc field indicates that
* we've potentially lost a feature bit and we should check it anyway.
+ *
+ * However, past bugs (i.e. in growfs) left non-zeroed regions beyond the
+ * last field in V4 secondary superblocks. So for secondary superblocks,
+ * we are more forgiving, and ignore CRC failures if the primary doesn't
+ * indicate that the fs version is V5.
*/
static void
xfs_sb_read_verify(
@@ -769,8 +774,12 @@ xfs_sb_read_verify(
if (!xfs_verify_cksum(bp->b_addr, be16_to_cpu(dsb->sb_sectsize),
offsetof(struct xfs_sb, sb_crc))) {
- error = EFSCORRUPTED;
- goto out_error;
+ /* Only fail bad secondaries on a known V5 filesystem */
+ if (bp->b_bn != XFS_SB_DADDR &&
+ xfs_sb_version_hascrc(&mp->m_sb)) {
+ error = EFSCORRUPTED;
+ goto out_error;
+ }
}
}
error = xfs_sb_verify(bp, true);
This is a note to let you know that I have just added a patch titled xfs: be more forgiving of a v4 secondary sb w/ junk in v5 fields to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 4ca70e5954382819b877003daa2339819c4bab95 Mon Sep 17 00:00:00 2001 From: Eric Sandeen <sandeen@sandeen.net> Date: Mon, 9 Sep 2013 15:33:29 -0500 Subject: xfs: be more forgiving of a v4 secondary sb w/ junk in v5 fields commit 10e6e65dfcedff63275c3d649d329c044caa8e26 upstream. Today, if xfs_sb_read_verify encounters a v4 superblock with junk past v4 fields which includes data in sb_crc, it will be treated as a failing checksum and a significant corruption. There are known prior bugs which leave junk at the end of the V4 superblock; we don't need to actually fail the verification in this case if other checks pan out ok. So if this is a secondary superblock, and the primary superblock doesn't indicate that this is a V5 filesystem, don't treat this as an actual checksum failure. We should probably check the garbage condition as we do in xfs_repair, and possibly warn about it or self-heal, but that's a different scope of work. Stable folks: This can go back to v3.10, which is what introduced the sb CRC checking that is tripped up by old, stale, incorrect V4 superblocks w/ unzeroed bits. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: Dave Chinner <david@fromorbit.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com> [ luis: backported to 3.5: - xfs_sb_read_verify() is defined in fs/xfs/xfs_mount.c in 3.11 ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- fs/xfs/xfs_mount.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) -- 1.8.3.2