From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 904AB7F5F for ; Mon, 9 Sep 2013 16:08:47 -0500 (CDT) Message-ID: <522E38DB.4020408@sgi.com> Date: Mon, 09 Sep 2013 16:08:43 -0500 From: Mark Tinguely MIME-Version: 1.0 Subject: Re: [PATCH V2] xfs: be more forgiving of a v4 secondary sb w/ junk in v5 fields References: <520D1BA3.1050500@redhat.com> <20130815210018.GR6023@dastard> <520D44E7.1000905@sandeen.net> <520D592D.4040600@redhat.com> <522E3099.1040503@sandeen.net> In-Reply-To: <522E3099.1040503@sandeen.net> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: "'linux-xfs@oss.sgi.com'" , Eric Sandeen On 09/09/13 15:33, Eric Sandeen wrote: > 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 > --- > > V2: Comment changes: More! (No code changes) > > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c > index 2b0ba35..b2deab1 100644 > --- a/fs/xfs/xfs_mount.c > +++ b/fs/xfs/xfs_mount.c > @@ -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 moved to fs/xfs/xfs_sb.c in TOT, but the patch looks good to me. Reviewed-by: Mark Tinguely _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs