From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 801C87F5F for ; Mon, 9 Sep 2013 16:10:29 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 6CE19304051 for ; Mon, 9 Sep 2013 14:10:26 -0700 (PDT) Received: from sandeen.net (sandeen.net [63.231.237.45]) by cuda.sgi.com with ESMTP id yXcHXdvLeuGjAEUj for ; Mon, 09 Sep 2013 14:10:25 -0700 (PDT) Message-ID: <522E393E.10902@sandeen.net> Date: Mon, 09 Sep 2013 16:10:22 -0500 From: Eric Sandeen 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> <522E38DB.4020408@sgi.com> In-Reply-To: <522E38DB.4020408@sgi.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Mark Tinguely Cc: "'linux-xfs@oss.sgi.com'" , Eric Sandeen On 9/9/13 4:08 PM, Mark Tinguely wrote: > 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. Whoops, sorry. Thanks for the review. Want a resend? (Any idea why your mail client eats spaces? "if (bp->b_bn != XFS_SB_DADDR&&" isn't in the original patch...) > Reviewed-by: Mark Tinguely Thanks, -Eric _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs