xfs: be more forgiving of a v4 secondary sb w/ junk in v5 fields
authorEric Sandeen <sandeen@sandeen.net>
Mon, 9 Sep 2013 20:33:29 +0000 (15:33 -0500)
committerBen Myers <bpm@sgi.com>
Wed, 30 Oct 2013 21:38:29 +0000 (16:38 -0500)
commit10e6e65dfcedff63275c3d649d329c044caa8e26
treec2b36e18acb66c25dd339538f6b5b6ab6e922367
parent643f7c4e5656bd18c769211f933190f7bb738245
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>
fs/xfs/xfs_sb.c