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authorEric Sandeen <sandeen@sandeen.net>2013-09-09 15:33:29 -0500
committerBen Myers <bpm@sgi.com>2013-10-30 16:38:29 -0500
commit10e6e65dfcedff63275c3d649d329c044caa8e26 (patch)
treec2b36e18acb66c25dd339538f6b5b6ab6e922367 /fs/xfs
parent643f7c4e5656bd18c769211f933190f7bb738245 (diff)
downloadop-kernel-dev-10e6e65dfcedff63275c3d649d329c044caa8e26.zip
op-kernel-dev-10e6e65dfcedff63275c3d649d329c044caa8e26.tar.gz
xfs: be more forgiving of a v4 secondary sb w/ junk in v5 fields
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. Cc: stable@vger.kernel.org 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>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_sb.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/xfs/xfs_sb.c b/fs/xfs/xfs_sb.c
index 13c7834..b7c9aea 100644
--- a/fs/xfs/xfs_sb.c
+++ b/fs/xfs/xfs_sb.c
@@ -588,6 +588,11 @@ 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(
@@ -608,8 +613,12 @@ 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);
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