From patchwork Sun Dec 2 18:08:32 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10708137 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CD55413BB for ; Sun, 2 Dec 2018 18:09:07 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AB81C2A81B for ; Sun, 2 Dec 2018 18:09:07 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9A0922A81D; Sun, 2 Dec 2018 18:09:07 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 361F32A74B for ; Sun, 2 Dec 2018 18:09:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725613AbeLBSJI (ORCPT ); Sun, 2 Dec 2018 13:09:08 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:38876 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725554AbeLBSJI (ORCPT ); Sun, 2 Dec 2018 13:09:08 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wB2I8bOs133887; Sun, 2 Dec 2018 18:08:37 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : mime-version : content-type; s=corp-2018-07-02; bh=FD407ow1hQpA8GCIcVeHNP2opeh/znRCCGyjtnQmblU=; b=Rpt4VHtyBGbCCnJ47CTaa+6i9/qWV5VCU1E2zcrN3rCib0dnkTirZ7ykVjmWKhovDRKI FaDZBQydD4oCDmLhiaBbuCn5BtjVFTPx8Gt3cbKajHM1jtSZOhKqKesbI3IMTko0+Hte yHDPBdrUlaR16KthEW0NQ0CQYbGTCv6oW2GuKpfbIqwl4nktzl83gDGbjrESQMTB1nmi nG6fopXnhl4qKwOB56t0kfQN75dYWLplqNpMeHlT2mGsdoCJscdojuy1O9RAgsmLwdK3 f2TwErhQ/QBmXhG7BstAIVr4PSl9qMOsFR1Zkgg3bYxkPQO8bPaAqYLb1W9TF6EBKZ3v aA== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2p3j8q34sp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 02 Dec 2018 18:08:36 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wB2I8aME001194 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 2 Dec 2018 18:08:36 GMT Received: from abhmp0010.oracle.com (abhmp0010.oracle.com [141.146.116.16]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id wB2I8XEG032132; Sun, 2 Dec 2018 18:08:34 GMT Received: from localhost (/10.159.151.183) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 02 Dec 2018 10:08:33 -0800 Date: Sun, 2 Dec 2018 10:08:32 -0800 From: "Darrick J. Wong" To: Amir Goldstein , Dave Chinner Cc: jencce.kernel@gmail.com, linux-xfs , overlayfs , Zorro Lang , fstests , linux-fsdevel , Christoph Hellwig Subject: [PATCH v2 1/2] splice: don't read more than available pipe space Message-ID: <20181202180832.GR8125@magnolia> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9095 signatures=668686 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=8.0.1-1810050000 definitions=main-1812020174 Sender: fstests-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: fstests@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Darrick J. Wong In commit 4721a601099, we tried to fix a problem wherein directio reads into a splice pipe will bounce EFAULT/EAGAIN all the way out to userspace by simulating a zero-byte short read. This happens because some directio read implementations (xfs) will call bio_iov_iter_get_pages to grab pipe buffer pages and issue asynchronous reads, but as soon as we run out of pipe buffers that _get_pages call returns EFAULT, which the splice code translates to EAGAIN and bounces out to userspace. In that commit, the iomap code catches the EFAULT and simulates a zero-byte read, but that causes assertion errors on regular splice reads because xfs doesn't allow short directio reads. The brokenness is compounded by splice_direct_to_actor immediately bailing on do_splice_to returning <= 0 without ever calling ->actor (which empties out the pipe), so if userspace calls back we'll EFAULT again on the full pipe, and nothing ever gets copied. Therefore, teach splice_direct_to_actor to clamp its requests to the amount of free space in the pipe and remove the simulated short read from the iomap directio code. Fixes: 4721a601099 ("iomap: dio data corruption and spurious errors when pipes fill") Reported-by: Amir Goldstein Reviewed-by: Christoph Hellwig Signed-off-by: Darrick J. Wong --- v2: split into two parts per hch request --- fs/splice.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/splice.c b/fs/splice.c index 3553f1956508..4bd9d9590199 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -949,7 +949,10 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, size_t read_len; loff_t pos = sd->pos, prev_pos = pos; - ret = do_splice_to(in, &pos, pipe, len, flags); + /* Don't try to read more the pipe has space for. */ + read_len = min_t(size_t, len, + (pipe->buffers - pipe->nrbufs) << PAGE_SHIFT); + ret = do_splice_to(in, &pos, pipe, read_len, flags); if (unlikely(ret <= 0)) goto out_release; From patchwork Sun Dec 2 18:10:45 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10708143 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8CBC0109C for ; Sun, 2 Dec 2018 18:11:08 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7DA2F2A799 for ; Sun, 2 Dec 2018 18:11:08 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 71FCB2A820; Sun, 2 Dec 2018 18:11:08 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 174032A799 for ; Sun, 2 Dec 2018 18:11:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725786AbeLBSLK (ORCPT ); Sun, 2 Dec 2018 13:11:10 -0500 Received: from aserp2120.oracle.com ([141.146.126.78]:40300 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725535AbeLBSLJ (ORCPT ); Sun, 2 Dec 2018 13:11:09 -0500 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wB2I8b0Y133893; Sun, 2 Dec 2018 18:10:49 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-2018-07-02; bh=fo5WD0HQVBpt7GT0fxmVc0UQDu+AViXsnmk0oIJ5lvw=; b=AhQCGLIyU2v07S3v5woeG4QZJroR4ZvHMowsAc+ADQ7XZAmg3wFyw41VJ9eOW/VVGDn/ jtzE3b7FsCJ+8plwiueVHNJ7bqFvUlsmkEq3jMsyC3CGt2it1avuHNU6QA0gruCGL40A iLX13UuyEmbx1DSnPhzIE/aM/GyXZs/ythEoOaSSAY28QU6F33NV7J9/nXBTYRM3pyOi bS/CBZ549hf4I9hHyKh/OQUiF3hU8ELiBCSyXXv//l3lJSbKQHmyfNg+hDTD2rMDbOZ+ 1tEywPAANfgvjFL321PPc5WZnA7b8ve9E192/j31WsUKUByTHxUqM8DjC2RUIcZD8z5N Aw== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2120.oracle.com with ESMTP id 2p3j8q34vj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 02 Dec 2018 18:10:48 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wB2IAmWj026933 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sun, 2 Dec 2018 18:10:48 GMT Received: from abhmp0005.oracle.com (abhmp0005.oracle.com [141.146.116.11]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id wB2IAl3I019418; Sun, 2 Dec 2018 18:10:47 GMT Received: from localhost (/10.159.151.183) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sun, 02 Dec 2018 10:10:47 -0800 Date: Sun, 2 Dec 2018 10:10:45 -0800 From: "Darrick J. Wong" To: Amir Goldstein , Dave Chinner Cc: jencce.kernel@gmail.com, linux-xfs , overlayfs , Zorro Lang , fstests , linux-fsdevel , Christoph Hellwig Subject: [PATCH v2 2/2] iomap: partially revert 4721a601099 (simulated directio short read on EFAULT) Message-ID: <20181202181045.GS8125@magnolia> References: <20181202180832.GR8125@magnolia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181202180832.GR8125@magnolia> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9095 signatures=668686 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812020174 Sender: fstests-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: fstests@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Darrick J. Wong In commit 4721a601099, we tried to fix a problem wherein directio reads into a splice pipe will bounce EFAULT/EAGAIN all the way out to userspace by simulating a zero-byte short read. This happens because some directio read implementations (xfs) will call bio_iov_iter_get_pages to grab pipe buffer pages and issue asynchronous reads, but as soon as we run out of pipe buffers that _get_pages call returns EFAULT, which the splice code translates to EAGAIN and bounces out to userspace. In that commit, the iomap code catches the EFAULT and simulates a zero-byte read, but that causes assertion errors on regular splice reads because xfs doesn't allow short directio reads. This causes infinite splice() loops and assertion failures on generic/095 on overlayfs because xfs only permit total success or total failure of a directio operation. The underlying issue in the pipe splice code has now been fixed by changing the pipe splice loop to avoid avoid reading more data than there is space in the pipe. Therefore, it's no longer necessary to simulate the short directio, so remove the hack from iomap. Fixes: 4721a601099 ("iomap: dio data corruption and spurious errors when pipes fill") Reported-by: Amir Goldstein Reviewed-by: Christoph Hellwig Signed-off-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- v2: split into two patches per hch request --- fs/iomap.c | 9 --------- 1 file changed, 9 deletions(-) diff --git a/fs/iomap.c b/fs/iomap.c index 3ffb776fbebe..d6bc98ae8d35 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -1877,15 +1877,6 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, dio->wait_for_completion = true; ret = 0; } - - /* - * Splicing to pipes can fail on a full pipe. We have to - * swallow this to make it look like a short IO - * otherwise the higher splice layers will completely - * mishandle the error and stop moving data. - */ - if (ret == -EFAULT) - ret = 0; break; } pos += ret;