From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 26E0AC433E0 for ; Thu, 25 Jun 2020 21:49:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F3ECF20789 for ; Thu, 25 Jun 2020 21:49:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390510AbgFYVtS (ORCPT ); Thu, 25 Jun 2020 17:49:18 -0400 Received: from mail107.syd.optusnet.com.au ([211.29.132.53]:41660 "EHLO mail107.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389963AbgFYVtS (ORCPT ); Thu, 25 Jun 2020 17:49:18 -0400 Received: from dread.disaster.area (pa49-180-53-24.pa.nsw.optusnet.com.au [49.180.53.24]) by mail107.syd.optusnet.com.au (Postfix) with ESMTPS id EA0D9D59982; Fri, 26 Jun 2020 07:49:13 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1joZk7-0000ZL-2u; Fri, 26 Jun 2020 07:49:11 +1000 Date: Fri, 26 Jun 2020 07:49:11 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: xfs , Brian Foster Subject: Re: [PATCH v4] xfs: don't eat an EIO/ENOSPC writeback error when scrubbing data fork Message-ID: <20200625214911.GE2005@dread.disaster.area> References: <20200625011643.GJ7625@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200625011643.GJ7625@magnolia> User-Agent: Mutt/1.10.1 (2018-07-13) X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=W5xGqiek c=1 sm=1 tr=0 a=moVtWZxmCkf3aAMJKIb/8g==:117 a=moVtWZxmCkf3aAMJKIb/8g==:17 a=kj9zAlcOel0A:10 a=nTHF0DUjJn0A:10 a=yPCof4ZbAAAA:8 a=20KFwNOVAAAA:8 a=7-415B0cAAAA:8 a=1Tq5uGCwEe95VkJqrwsA:9 a=bjKgapt9jWoZRjqa:21 a=KsNI6vUMcgsd9x59:21 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Wed, Jun 24, 2020 at 06:16:43PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > The data fork scrubber calls filemap_write_and_wait to flush dirty pages > and delalloc reservations out to disk prior to checking the data fork's > extent mappings. Unfortunately, this means that scrub can consume the > EIO/ENOSPC errors that would otherwise have stayed around in the address > space until (we hope) the writer application calls fsync to persist data > and collect errors. The end result is that programs that wrote to a > file might never see the error code and proceed as if nothing were > wrong. > > xfs_scrub is not in a position to notify file writers about the > writeback failure, and it's only here to check metadata, not file > contents. Therefore, if writeback fails, we should stuff the error code > back into the address space so that an fsync by the writer application > can pick that up. > > Fixes: 99d9d8d05da2 ("xfs: scrub inode block mappings") > Signed-off-by: Darrick J. Wong > --- > v4: remove if block that only had a gigantic comment > v3: don't play this game where we clear the mapping error only to re-set it > v2: explain why it's ok to keep going even if writeback fails > --- > fs/xfs/scrub/bmap.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c > index 7badd6dfe544..955302e7cdde 100644 > --- a/fs/xfs/scrub/bmap.c > +++ b/fs/xfs/scrub/bmap.c > @@ -45,9 +45,27 @@ xchk_setup_inode_bmap( > */ > if (S_ISREG(VFS_I(sc->ip)->i_mode) && > sc->sm->sm_type == XFS_SCRUB_TYPE_BMBTD) { > + struct address_space *mapping = VFS_I(sc->ip)->i_mapping; > + > inode_dio_wait(VFS_I(sc->ip)); > - error = filemap_write_and_wait(VFS_I(sc->ip)->i_mapping); > - if (error) > + > + /* > + * Try to flush all incore state to disk before we examine the > + * space mappings for the data fork. Leave accumulated errors > + * in the mapping for the writer threads to consume. > + * > + * On ENOSPC or EIO writeback errors, we continue into the > + * extent mapping checks because write failures do not > + * necessarily imply anything about the correctness of the file > + * metadata. The metadata and the file data could be on > + * completely separate devices; a media failure might only > + * affect a subset of the disk, etc. We can handle delalloc > + * extents in the scrubber, so leaving them in memory is fine. > + */ > + error = filemap_fdatawrite(mapping); > + if (!error) > + error = filemap_fdatawait_keep_errors(mapping); > + if (error && (error != -ENOSPC && error != -EIO)) > goto out; > } looks good. Reviewed-by: Dave Chinner -- Dave Chinner david@fromorbit.com