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 DD8DC7F47 for ; Tue, 25 Aug 2015 19:55:02 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay1.corp.sgi.com (Postfix) with ESMTP id C9BC28F8049 for ; Tue, 25 Aug 2015 17:55:02 -0700 (PDT) Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id kBlWs6mAcmkfR3j9 for ; Tue, 25 Aug 2015 17:55:00 -0700 (PDT) Date: Wed, 26 Aug 2015 10:54:47 +1000 From: Dave Chinner Subject: Re: [PATCH 07/11] xfs_repair: force not-so-bad bmbt blocks back through the verifier Message-ID: <20150826005447.GS714@dastard> References: <20150826003220.23973.59731.stgit@birch.djwong.org> <20150826003305.23973.65768.stgit@birch.djwong.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20150826003305.23973.65768.stgit@birch.djwong.org> 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: "Darrick J. Wong" Cc: xfs@oss.sgi.com On Tue, Aug 25, 2015 at 05:33:05PM -0700, Darrick J. Wong wrote: > If during prefetch we encounter a bmbt block that fails the CRC check > due to corruption in the unused part of the block, force the buffer > back through the non-prefetch verifiers later so that the CRC is > updated. Otherwise, the bad checksum goes unfixed and the kernel will > still flag the bmbt block as invalid. > > Signed-off-by: Darrick J. Wong > --- > repair/prefetch.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > > diff --git a/repair/prefetch.c b/repair/prefetch.c > index 1de3ec0..77d29c8 100644 > --- a/repair/prefetch.c > +++ b/repair/prefetch.c > @@ -276,6 +276,14 @@ pf_scan_lbtree( > > XFS_BUF_SET_PRIORITY(bp, isadir ? B_DIR_BMAP : B_BMAP); > > + /* > + * Make this bmbt buffer go back through the verifiers later so that > + * we correct checksum errors stemming from bitflips in the unused > + * parts of the bmbt block. > + */ > + if (bp->b_error == -EFSBADCRC) > + bp->b_flags |= LIBXFS_B_UNCHECKED; This is because the next read of the buffer clears bp->b_error, right? So, while I think this is necessary, I also think the prefetch on this btree should stop as we can't trust the contents of the buffer to be correct. Hence I'd suggest that: /* * If the verfier flagged a problem with the buffer, we * can't trust it's contents for the purposes of readahead. * Stop prefetching the tree, and mark this buffer as * unchecked so that the next read of the buffer by the * repair code will retain the error status and hence be * acted on appropriately. */ if (bp->b_error) { bp->b_flags |= LIBXFS_B_UNCHECKED; libxfs_putbuf(bp); return 0; } Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs