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=-9.9 required=3.0 tests=BAYES_00,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=unavailable 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 A7FADC55179 for ; Thu, 29 Oct 2020 16:13:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E5AE20838 for ; Thu, 29 Oct 2020 16:13:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="E1Jkqt18" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725965AbgJ2QNM (ORCPT ); Thu, 29 Oct 2020 12:13:12 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:42380 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725855AbgJ2QNL (ORCPT ); Thu, 29 Oct 2020 12:13:11 -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 09TG9ErG156978; Thu, 29 Oct 2020 16:13:03 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=bHoj8umFYPWY0A4MzESGkhTRt3TkvuqQ/Jd2QnoOiOI=; b=E1Jkqt18IAvScHjQeJ0D3iY4zyIVReT6u/g9R8MHzatXcY8ZG6jGOljbg0UoQ3wKdUHT pZZgetr6FBx27f+/yvjzoSqMvnWDvGWHuHPrvrc37LRmcJUNdtRCEh/bc1L33Fz/AjGS wqiUmlhjA8j5yHEWNJrepiQPidF8WZhYvg/s54Uh7wv8of8/ph+8X0NVDN9VkNbPnmN4 4QTgqsdSq+H3vI9TSNRbGGC62u6Ta24ZtQd7he4ed4JcKMCiXkhCp0h5fysX14x6UaTi /+NfFhjxbRVr2gLZrhdEQPCUHWtv26jLi4WoTug0zFpYyHRV40+GyYZdpu7wvITnbfFK Tg== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2120.oracle.com with ESMTP id 34cc7m5rph-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 29 Oct 2020 16:13:03 +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 09TGAYFb175310; Thu, 29 Oct 2020 16:13:02 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3030.oracle.com with ESMTP id 34cwupy18e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 29 Oct 2020 16:13:02 +0000 Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 09TGD07E031655; Thu, 29 Oct 2020 16:13:00 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 29 Oct 2020 09:13:00 -0700 Date: Thu, 29 Oct 2020 09:12:58 -0700 From: "Darrick J. Wong" To: Brian Foster Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v2 2/3] iomap: support partial page discard on writeback block mapping failure Message-ID: <20201029161258.GA1061246@magnolia> References: <20201029132325.1663790-1-bfoster@redhat.com> <20201029132325.1663790-3-bfoster@redhat.com> <20201029152718.GK1061252@magnolia> <20201029160732.GA1660404@bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201029160732.GA1660404@bfoster> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9788 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 mlxscore=0 bulkscore=0 spamscore=0 adultscore=0 malwarescore=0 mlxlogscore=999 suspectscore=1 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010290113 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9788 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 adultscore=0 malwarescore=0 spamscore=0 clxscore=1015 mlxscore=0 suspectscore=1 priorityscore=1501 impostorscore=0 bulkscore=0 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2010290113 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Oct 29, 2020 at 12:07:32PM -0400, Brian Foster wrote: > On Thu, Oct 29, 2020 at 08:27:18AM -0700, Darrick J. Wong wrote: > > On Thu, Oct 29, 2020 at 09:23:24AM -0400, Brian Foster wrote: > > > iomap writeback mapping failure only calls into ->discard_page() if > > > the current page has not been added to the ioend. Accordingly, the > > > XFS callback assumes a full page discard and invalidation. This is > > > problematic for sub-page block size filesystems where some portion > > > of a page might have been mapped successfully before a failure to > > > map a delalloc block occurs. ->discard_page() is not called in that > > > error scenario and the bio is explicitly failed by iomap via the > > > error return from ->prepare_ioend(). As a result, the filesystem > > > leaks delalloc blocks and corrupts the filesystem block counters. > > > > > > Since XFS is the only user of ->discard_page(), tweak the semantics > > > to invoke the callback unconditionally on mapping errors and provide > > > the file offset that failed to map. Update xfs_discard_page() to > > > discard the corresponding portion of the file and pass the range > > > along to iomap_invalidatepage(). The latter already properly handles > > > both full and sub-page scenarios by not changing any iomap or page > > > state on sub-page invalidations. > > > > > > Signed-off-by: Brian Foster > > > --- > > > fs/iomap/buffered-io.c | 15 ++++++++------- > > > fs/xfs/xfs_aops.c | 13 +++++++------ > > > include/linux/iomap.h | 2 +- > > > 3 files changed, 16 insertions(+), 14 deletions(-) > > > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > > index bcfc288dba3f..d1f04eabc7e4 100644 > > > --- a/fs/iomap/buffered-io.c > > > +++ b/fs/iomap/buffered-io.c > > > @@ -1412,14 +1412,15 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, > > > * appropriately. > > > */ > > > if (unlikely(error)) { > > > + /* > > > + * Let the filesystem know what portion of the current page > > > + * failed to map. If the page wasn't been added to ioend, it > > > + * won't be affected by I/O completion and we must unlock it > > > + * now. > > > + */ > > > + if (wpc->ops->discard_page) > > > + wpc->ops->discard_page(page, file_offset); > > > if (!count) { > > > - /* > > > - * If the current page hasn't been added to ioend, it > > > - * won't be affected by I/O completions and we must > > > - * discard and unlock it right here. > > > - */ > > > - if (wpc->ops->discard_page) > > > - wpc->ops->discard_page(page); > > > ClearPageUptodate(page); > > > unlock_page(page); > > > goto done; > > > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c > > > index b35611882ff9..46920c530b20 100644 > > > --- a/fs/xfs/xfs_aops.c > > > +++ b/fs/xfs/xfs_aops.c > > > @@ -527,13 +527,14 @@ xfs_prepare_ioend( > > > */ > > > static void > > > xfs_discard_page( > > > - struct page *page) > > > + struct page *page, > > > + loff_t fileoff) > > > { > > > struct inode *inode = page->mapping->host; > > > struct xfs_inode *ip = XFS_I(inode); > > > struct xfs_mount *mp = ip->i_mount; > > > - loff_t offset = page_offset(page); > > > - xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, offset); > > > + unsigned int pageoff = offset_in_page(fileoff); > > > + xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, fileoff); > > > int error; > > > > > > if (XFS_FORCED_SHUTDOWN(mp)) > > > @@ -541,14 +542,14 @@ xfs_discard_page( > > > > > > xfs_alert_ratelimited(mp, > > > "page discard on page "PTR_FMT", inode 0x%llx, offset %llu.", > > > - page, ip->i_ino, offset); > > > + page, ip->i_ino, fileoff); > > > > > > error = xfs_bmap_punch_delalloc_range(ip, start_fsb, > > > - PAGE_SIZE / i_blocksize(inode)); > > > + (PAGE_SIZE - pageoff) / i_blocksize(inode)); > > > > Er... could you rebase this against 5.10-rc1, please? willy changed > > that line to not use PAGE_SIZE directly. > > > > Sure.. (note that there's still a PAGE_SIZE usage in the > iomap_invalidatepage() call). I think he has more for 5.11, but in the meantime it's just fixing the merge conflicts. :) > > I /think/ the way to resolve the merge conflict here is to change this > > last argument to: > > > > (i_blocks_per_page(page) - pageoff) / i_blocksize(inode) > > > > Hmm... pageoff is bytes so that doesn't look quite right. How about > something like this? > > ... > unsigned int pageoff = offset_in_page(fileoff); > xfs_fileoff_t pageoff_fsb = XFS_B_TO_FSBT(mp, pageoff); > > ... > error = xfs_bmap_punch_delalloc_range(ip, start_fsb, > i_blocks_per_page(inode, page) - pageoff_fsb); > ... You could probably combine the two variables, but otherwise that looks fine to me. --D > > Brian > > > --D > > > > > if (error && !XFS_FORCED_SHUTDOWN(mp)) > > > xfs_alert(mp, "page discard unable to remove delalloc mapping."); > > > out_invalidate: > > > - iomap_invalidatepage(page, 0, PAGE_SIZE); > > > + iomap_invalidatepage(page, pageoff, PAGE_SIZE - pageoff); > > > } > > > > > > static const struct iomap_writeback_ops xfs_writeback_ops = { > > > diff --git a/include/linux/iomap.h b/include/linux/iomap.h > > > index 4d1d3c3469e9..36e0ab19210a 100644 > > > --- a/include/linux/iomap.h > > > +++ b/include/linux/iomap.h > > > @@ -220,7 +220,7 @@ struct iomap_writeback_ops { > > > * Optional, allows the file system to discard state on a page where > > > * we failed to submit any I/O. > > > */ > > > - void (*discard_page)(struct page *page); > > > + void (*discard_page)(struct page *page, loff_t fileoff); > > > }; > > > > > > struct iomap_writepage_ctx { > > > -- > > > 2.25.4 > > > > > >