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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY 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 B912FC433DF for ; Tue, 23 Jun 2020 15:23:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F5602078A for ; Tue, 23 Jun 2020 15:23:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="haG/nMSn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732982AbgFWPX5 (ORCPT ); Tue, 23 Jun 2020 11:23:57 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:39910 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732781AbgFWPX4 (ORCPT ); Tue, 23 Jun 2020 11:23:56 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05NFHmAM051598; Tue, 23 Jun 2020 15:23:52 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=xwXufsJvimn1soPQI7IXckY4J6Vlj3BJTG2KUrX7pgU=; b=haG/nMSn3UkSTkvV8rZNR5LXgK2mDmb3uJZ9fvjgPCNU4IVMUy5ZLIvs8YPKzooBVTur OHEhRSxwd/KnKhzjaXxBvGZM4nHxFylN05nLfQFJNkapWjcVBwbrjr+am1uV2Lcc1JUK bphBCudvGlU7i5BmpKKay/3wcYKsfmnDj6sSGFNYh/7p9yIRwzgpI7ZheT+rSameiTHz cBOkrY940iTAARLXLXTTMnCxZTx56/NVgiT9zNyi9F+J0bYpRf1dznaIe3MCa3S691DE qmWDyyjOa9MxjprJo8Yam3RHDJLoNzCmCuboS605Sb+qabclJ+zfLuSAQU8na8uaH4XC JA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2120.oracle.com with ESMTP id 31uk3c0hwj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 23 Jun 2020 15:23:52 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05NFHjli175327; Tue, 23 Jun 2020 15:23:52 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 31uk3cbycx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 23 Jun 2020 15:23:52 +0000 Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 05NFNptw002334; Tue, 23 Jun 2020 15:23:51 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 23 Jun 2020 15:23:51 +0000 Date: Tue, 23 Jun 2020 08:23:50 -0700 From: "Darrick J. Wong" To: Brian Foster Cc: xfs , Dave Chinner Subject: Re: [PATCH v2] xfs: don't eat an EIO/ENOSPC writeback error when scrubbing data fork Message-ID: <20200623152350.GE7625@magnolia> References: <20200623035010.GF7606@magnolia> <20200623121031.GB55038@bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623121031.GB55038@bfoster> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9661 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 malwarescore=0 phishscore=0 suspectscore=1 bulkscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006120000 definitions=main-2006230118 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9661 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 priorityscore=1501 phishscore=0 suspectscore=1 mlxlogscore=999 bulkscore=0 spamscore=0 clxscore=1015 mlxscore=0 impostorscore=0 adultscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006120000 definitions=main-2006230118 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Jun 23, 2020 at 08:10:31AM -0400, Brian Foster wrote: > On Mon, Jun 22, 2020 at 08:50:10PM -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 > > --- > > v2: explain why it's ok to keep going even if writeback fails > > --- > > fs/xfs/scrub/bmap.c | 19 ++++++++++++++++++- > > 1 file changed, 18 insertions(+), 1 deletion(-) > > > > diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c > > index 7badd6dfe544..0d7062b7068b 100644 > > --- a/fs/xfs/scrub/bmap.c > > +++ b/fs/xfs/scrub/bmap.c > > @@ -47,7 +47,24 @@ xchk_setup_inode_bmap( > > sc->sm->sm_type == XFS_SCRUB_TYPE_BMBTD) { > > inode_dio_wait(VFS_I(sc->ip)); > > error = filemap_write_and_wait(VFS_I(sc->ip)->i_mapping); > > - if (error) > > + if (error == -ENOSPC || error == -EIO) { > > + /* > > + * If writeback hits EIO or ENOSPC, reflect it back > > + * into the address space mapping so that a writer > > + * program calling fsync to look for errors will still > > + * capture the error. > > + * > > + * However, 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 properly > > + * account for delalloc extents, so leaving them in > > + * memory is fine. > > + */ > > + mapping_set_error(VFS_I(sc->ip)->i_mapping, error); > > I think the more appropriate thing to do is open code the data write and > wait and use the variants of the latter that don't consume address space > errors in the first place (i.e. filemap_fdatawait_keep_errors()). Then > we wouldn't need the special error handling branch or perhaps the first > part of the comment. Hm? Yes, it's certainly possible. I don't want to go opencoding more vfs methods (like some e4 filesystems do) so I'll propose that as a second patch for 5.9. On second thought, I wonder if I should just drop the flush entirely? It's not a huge burden to skip past the delalloc reservations. Hmmm. Any preferences? --D > Brian > > > + } else if (error) > > goto out; > > } > > > > >