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 90AD17F55 for ; Mon, 9 Sep 2013 16:16:06 -0500 (CDT) Message-ID: <522E3A95.40309@sgi.com> Date: Mon, 09 Sep 2013 16:16:05 -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> <522E38DB.4020408@sgi.com> <522E393E.10902@sandeen.net> In-Reply-To: <522E393E.10902@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 16:10, Eric Sandeen wrote: > 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? Since Ben will do all the work, not necessary. ;) > > (Any idea why your mail client eats spaces? "if (bp->b_bn != XFS_SB_DADDR&&" isn't > in the original patch...) Dave mentioned that too before, I will check into it. --Mark. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs