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, URIBL_BLOCKED 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 396D0C433DF for ; Tue, 23 Jun 2020 03:50:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 169FB206C3 for ; Tue, 23 Jun 2020 03:50:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="B9ble4hf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731833AbgFWDui (ORCPT ); Mon, 22 Jun 2020 23:50:38 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:52790 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731216AbgFWDui (ORCPT ); Mon, 22 Jun 2020 23:50:38 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05N3adm8174109; Tue, 23 Jun 2020 03:50:36 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=txYLDsDJf1Ai/L/FItdqLLa0I28ZhhdLycQRmr3CXrk=; b=B9ble4hf3k0wAoR7bgd0+HAuF5oSnnuDsQm+aKPVMN/gPO2cgjOjjg4ITrzZijMk/ONU pAi2YIs2IaJd1P2ckbT93WIdjMmAc5xsCuDlzM/IBYyn/Uv6Z0tSz0gyKf/aBpb/t09+ XEM/I1OfQVdsTFC7gL8orP7jIS4jvtx27JmaPYALIcjK83BDGOTiq69wy/v0luF27nt3 JNZu7H/lXbmekFKzrCjTBktP2sOAVWiXWAyAHsFNaquLpEjmG6m4VvPawc6PaokJhisJ VMyCjjdK62d2HNzD2PMrtFv25pMRqQHzwumpbm2o+cOG8Kkf5ITfGUzxXhToBHvHWDAU xg== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2130.oracle.com with ESMTP id 31sebbjrn3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 23 Jun 2020 03:50:36 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05N3h6X6035391; Tue, 23 Jun 2020 03:50:36 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 31svcw35ap-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 23 Jun 2020 03:50:36 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 05N3oZWY015520; Tue, 23 Jun 2020 03:50:35 GMT Received: from localhost (/10.159.143.140) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 23 Jun 2020 03:50:35 +0000 Date: Mon, 22 Jun 2020 20:50:34 -0700 From: "Darrick J. Wong" To: Dave Chinner Cc: xfs Subject: Re: [PATCH] xfs: don't eat an EIO/ENOSPC writeback error when scrubbing data fork Message-ID: <20200623035034.GC7625@magnolia> References: <20200622171713.GG11245@magnolia> <20200622220839.GV2005@dread.disaster.area> <20200622232843.GA7625@magnolia> <20200622235800.GX2005@dread.disaster.area> <20200623010240.GB7625@magnolia> <20200623023710.GY2005@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200623023710.GY2005@dread.disaster.area> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9660 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 bulkscore=0 adultscore=0 malwarescore=0 suspectscore=1 phishscore=0 mlxscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006230026 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9660 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 cotscore=-2147483648 mlxscore=0 phishscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 suspectscore=1 clxscore=1015 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006230025 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 12:37:10PM +1000, Dave Chinner wrote: > On Mon, Jun 22, 2020 at 06:02:40PM -0700, Darrick J. Wong wrote: > > On Tue, Jun 23, 2020 at 09:58:00AM +1000, Dave Chinner wrote: > > > On Mon, Jun 22, 2020 at 04:28:43PM -0700, Darrick J. Wong wrote: > > > > On Tue, Jun 23, 2020 at 08:08:39AM +1000, Dave Chinner wrote: > > > > > On Mon, Jun 22, 2020 at 10:17:13AM -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 > > > > > > --- > > > > > > fs/xfs/scrub/bmap.c | 10 +++++++++- > > > > > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/fs/xfs/scrub/bmap.c b/fs/xfs/scrub/bmap.c > > > > > > index 7badd6dfe544..03be7cf3fe5a 100644 > > > > > > --- a/fs/xfs/scrub/bmap.c > > > > > > +++ b/fs/xfs/scrub/bmap.c > > > > > > @@ -47,7 +47,15 @@ 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. > > > > > > + */ > > > > > > + mapping_set_error(VFS_I(sc->ip)->i_mapping, error); > > > > > > + } else if (error) > > > > > > goto out; > > > > > > > > > > calling mapping_set_error() seems reasonable here and you've > > > > > explained that well, but shouldn't the error then be processed the > > > > > same way as all other errors? i.e. by jumping to out? > > > > > > > > > > If we are now continuing to scrub the bmap after ENOSPC/EIO occur, > > > > > why? > > > > > > > > Heh, ok, more explanation is needed. How about this? > > > > > > > > /* > > > > * 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. > > > > */ > > > > > > Ok. Does scrub deal with left-over delalloc extents correctly in > > > this case? > > > > It ignores the ones in the incore extent tree and flags them if they > > show up in the ondisk metadata. > > OK. Perhaps add this to the comment? ok, will do --D > Cheers, > > Dave. > -- > Dave Chinner > david@fromorbit.com