From patchwork Fri Aug 30 21:06:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 11124537 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DCC2A112C for ; Fri, 30 Aug 2019 21:06:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B83BD2343D for ; Fri, 30 Aug 2019 21:06:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="B6J8WGrL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728117AbfH3VGI (ORCPT ); Fri, 30 Aug 2019 17:06:08 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:43824 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727991AbfH3VGI (ORCPT ); Fri, 30 Aug 2019 17:06:08 -0400 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 x7UL4OP3052181; Fri, 30 Aug 2019 21:06:05 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 : content-transfer-encoding : in-reply-to; s=corp-2019-08-05; bh=X0qTs6quRkeDzh6JsWpMpr4j3/R7HoLuineFF9PtkUM=; b=B6J8WGrLpX/O5g43lTMjZEkpBTejd35tNxHNpt0F+VEYkvu1AIzN3AX/f8mey1uyZGXe eGpblgYW9tYltwOQAhSbMDbi1nt6LfAkI2dRyIIm1DAnIfR1I7RP52+IYw6zTxr0Wxa+ FMSAOFow9EtauioLvdND+3KysoaQirxMuZ95dGexrLWqmnAWAtGEC7ZbyTNhYpbhI5fi P8fzfNg5ztl8U7A3Jfv+ur1kG7CSObqkH4yoq5zqO99UKknvpuVeqdQ0F3FSJSyNunjs WXyGfuJHQ4Sf8m7KnmwF9w7ikDse1lMTKglkWdjb6M53fa0awMuoqyJRjnVgX3JBHy1Q mQ== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by aserp2120.oracle.com with ESMTP id 2uqbcx005j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 30 Aug 2019 21:06:05 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x7UL4EII066304; Fri, 30 Aug 2019 21:06:05 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 2uphavq7k3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 30 Aug 2019 21:06:05 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x7UL64xQ019365; Fri, 30 Aug 2019 21:06:04 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 30 Aug 2019 14:06:04 -0700 Date: Fri, 30 Aug 2019 14:06:03 -0700 From: "Darrick J. Wong" To: viro@zeniv.linux.org.uk, andreas.gruenbacher@gmail.com Cc: xfs , linux-fsdevel Subject: [PATCH v2] splice: only read in as much information as there is pipe buffer space Message-ID: <20190830210603.GB5340@magnolia> References: <20190829161155.GA5360@magnolia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190829161155.GA5360@magnolia> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9365 signatures=668685 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=8.0.1-1906280000 definitions=main-1908300202 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9365 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 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=8.0.1-1906280000 definitions=main-1908300202 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Darrick J. Wong Andreas Grünbacher reports that on the two filesystems that support iomap directio, it's possible for splice() to return -EAGAIN (instead of a short splice) if the pipe being written to has less space available in its pipe buffers than the length supplied by the calling process. Months ago we fixed splice_direct_to_actor to clamp the length of the read request to the size of the splice pipe. Do the same to do_splice. Fixes: 17614445576b6 ("splice: don't read more than available pipe space") Reported-by: Andreas Grünbacher Signed-off-by: Darrick J. Wong Reviewed-by: Andreas Grünbacher Tested-by: Andreas Grünbacher --- v2: tidy up the other call site per Andreas' request --- fs/splice.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index 98412721f056..2ddbace9129f 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -945,12 +945,13 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, WARN_ON_ONCE(pipe->nrbufs != 0); while (len) { + unsigned int pipe_pages; size_t read_len; loff_t pos = sd->pos, prev_pos = pos; /* Don't try to read more the pipe has space for. */ - read_len = min_t(size_t, len, - (pipe->buffers - pipe->nrbufs) << PAGE_SHIFT); + pipe_pages = pipe->buffers - pipe->nrbufs; + read_len = min(len, (size_t)pipe_pages << PAGE_SHIFT); ret = do_splice_to(in, &pos, pipe, read_len, flags); if (unlikely(ret <= 0)) goto out_release; @@ -1101,6 +1102,7 @@ static long do_splice(struct file *in, loff_t __user *off_in, struct pipe_inode_info *ipipe; struct pipe_inode_info *opipe; loff_t offset; + unsigned int pipe_pages; long ret; ipipe = get_pipe_info(in); @@ -1123,6 +1125,10 @@ static long do_splice(struct file *in, loff_t __user *off_in, if ((in->f_flags | out->f_flags) & O_NONBLOCK) flags |= SPLICE_F_NONBLOCK; + /* Don't try to read more the pipe has space for. */ + pipe_pages = opipe->buffers - opipe->nrbufs; + len = min(len, (size_t)pipe_pages << PAGE_SHIFT); + return splice_pipe_to_pipe(ipipe, opipe, len, flags); } @@ -1180,8 +1186,13 @@ static long do_splice(struct file *in, loff_t __user *off_in, pipe_lock(opipe); ret = wait_for_space(opipe, flags); - if (!ret) + if (!ret) { + /* Don't try to read more the pipe has space for. */ + pipe_pages = opipe->buffers - opipe->nrbufs; + len = min(len, (size_t)pipe_pages << PAGE_SHIFT); + ret = do_splice_to(in, &offset, opipe, len, flags); + } pipe_unlock(opipe); if (ret > 0) wakeup_pipe_readers(opipe);