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=-8.3 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, 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 69FACC33CA9 for ; Mon, 13 Jan 2020 21:52:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 381B22072B for ; Mon, 13 Jan 2020 21:52:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="j6eMW51U" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728769AbgAMVwS (ORCPT ); Mon, 13 Jan 2020 16:52:18 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:43898 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728755AbgAMVwS (ORCPT ); Mon, 13 Jan 2020 16:52:18 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00DLhrNl131209; Mon, 13 Jan 2020 21:52:03 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-2019-08-05; bh=8OFklpwMX2/C6RJSwi+fm6fYp/IFQq/XiSxcQChY2wM=; b=j6eMW51UMTwX2ljCfQdhee9fKu/Vp8P03c55D8NXqX09RE4eJJ5M1pUJjuJBtXOVzOvA k18MFaqQQ39drAqe1yV1vP+K8RLtueA/ol2O0YxJlcEqWIglvVgVUrGc2v8hJluDCUiZ LQBz20yK5wcyARmN2zs8ldLvNF3srACHaQoLZtHgWPk82LeKArsxj9P2X4yqCW4PAUCw 9qwM8skZKz7UZNg9O75dwLwFXX0isxDLYgNxWv19UdrbVHJmxrBq3KvpQfD6qHGYjka9 AqfL/qJ476yV1EEa+ICLQpF7XkvpX3/J4dyM/7NRPQlrRkL6OZ51xBZUJPr9YkXC98Az yA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2120.oracle.com with ESMTP id 2xf73thuky-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Jan 2020 21:52:03 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00DLmPVR083023; Mon, 13 Jan 2020 21:52:02 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 2xfrgjebsn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Jan 2020 21:52:02 +0000 Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 00DLq0vJ023482; Mon, 13 Jan 2020 21:52:00 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 13 Jan 2020 13:52:00 -0800 Date: Mon, 13 Jan 2020 13:51:59 -0800 From: "Darrick J. Wong" To: Ritesh Harjani Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, jack@suse.cz Subject: Re: [RFC 1/2] iomap: direct-io: Move inode_dio_begin before filemap_write_and_wait_range Message-ID: <20200113215159.GA8235@magnolia> References: <27607a16327fe9664f32d09abe565af0d1ae56c9.1578907891.git.riteshh@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <27607a16327fe9664f32d09abe565af0d1ae56c9.1578907891.git.riteshh@linux.ibm.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9499 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001130178 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9499 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001130177 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Mon, Jan 13, 2020 at 04:34:21PM +0530, Ritesh Harjani wrote: > Some filesystems (e.g. ext4) need to know in it's writeback path, that > whether DIO is in progress or not. This info may be needed to avoid the > stale data exposure race with DIO reads. Does XFS have this problem too? Admittedly dio read during mmap write is probably not well supported. ;) > Signed-off-by: Ritesh Harjani > --- > fs/iomap/direct-io.c | 17 +++++++++++++---- Might want to cc fsdevel and the iomap maintainers... --D > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c > index 23837926c0c5..d1c159bd3854 100644 > --- a/fs/iomap/direct-io.c > +++ b/fs/iomap/direct-io.c > @@ -468,9 +468,18 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > flags |= IOMAP_NOWAIT; > } > > + /* > + * Call inode_dio_begin() before we write out and wait for writeback to > + * complete. This may be needed by some filesystems to prevent race > + * like stale data exposure by DIO reads. > + */ > + inode_dio_begin(inode); > + /* So that i_dio_count is incremented before below operation */ > + smp_mb__after_atomic(); > + > ret = filemap_write_and_wait_range(mapping, pos, end); > if (ret) > - goto out_free_dio; > + goto out_end_dio; > > /* > * Try to invalidate cache pages for the range we're direct > @@ -488,11 +497,9 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > !inode->i_sb->s_dio_done_wq) { > ret = sb_init_dio_done_wq(inode->i_sb); > if (ret < 0) > - goto out_free_dio; > + goto out_end_dio; > } > > - inode_dio_begin(inode); > - > blk_start_plug(&plug); > do { > ret = iomap_apply(inode, pos, count, flags, ops, dio, > @@ -568,6 +575,8 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, > > return iomap_dio_complete(dio); > > +out_end_dio: > + inode_dio_end(inode); > out_free_dio: > kfree(dio); > return ret; > -- > 2.21.0 >