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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7870BC4BA3B for ; Thu, 27 Feb 2020 09:19:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B6F5222C2 for ; Thu, 27 Feb 2020 09:19:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="Mzto7rMY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728653AbgB0JTi (ORCPT ); Thu, 27 Feb 2020 04:19:38 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:38092 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728504AbgB0JTh (ORCPT ); Thu, 27 Feb 2020 04:19:37 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01R9F6Hl091510; Thu, 27 Feb 2020 09:19:28 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=d4b3D5DmveOIQH3fWRGTZrbAVm/isi1FEEnnWao0g3Q=; b=Mzto7rMY0tpW51J82egbXBwUzv80GMbUmMq+I+MPuPuT06flkQU7cEnFXvakSmEOPQUl 2FE94qyM26vHcglBUprf18NvBk/Yqtc+jBEYR6Rd7ia1J51MSHY/Sislq0/PGJo3lx4u UqwHhW83khyME/iq3oWXHJG8Sezjlp511+qV5P3816W8+mLB4QcjTt/Dnju2yMBRbt7B jglV0+YI5znbvlkZCNqgYphv+lTKb2ngvIAlJCyC4B9AS5daMsyRtEIaPSdyHdb2OAvo ImVUxGwzN9RyYtObMVp8Tb/df+wI5FJdsIFDOUan4sMjejc/lW+H3MWhMG+q2HPvf/Nj Mw== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2120.oracle.com with ESMTP id 2ydct39hds-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Feb 2020 09:19:28 +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 01R9EJiw172581; Thu, 27 Feb 2020 09:19:28 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3030.oracle.com with ESMTP id 2ydcs4mxj6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 27 Feb 2020 09:19:28 +0000 Received: from abhmp0009.oracle.com (abhmp0009.oracle.com [141.146.116.15]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 01R9JRun026400; Thu, 27 Feb 2020 09:19:27 GMT Received: from [192.168.1.14] (/114.88.246.185) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 27 Feb 2020 01:19:27 -0800 Subject: Re: [PATCH 1/4] io_uring: add IORING_OP_READ{WRITE}V_PI cmd To: Christoph Hellwig , Jens Axboe Cc: linux-block@vger.kernel.org, martin.petersen@oracle.com, linux-fsdevel@vger.kernel.org, darrick.wong@oracle.com, io-uring@vger.kernel.org References: <20200226083719.4389-1-bob.liu@oracle.com> <20200226083719.4389-2-bob.liu@oracle.com> <6e466774-4dc5-861c-58b5-f0cc728bacff@kernel.dk> <20200226155728.GA32543@infradead.org> <20200226165309.GA3995@infradead.org> From: Bob Liu Message-ID: Date: Thu, 27 Feb 2020 17:19:31 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20200226165309.GA3995@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9543 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 bulkscore=0 malwarescore=0 mlxlogscore=923 mlxscore=0 phishscore=0 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002270075 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9543 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 bulkscore=0 impostorscore=0 spamscore=0 priorityscore=1501 malwarescore=0 adultscore=0 phishscore=0 mlxlogscore=963 mlxscore=0 suspectscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002270075 Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 2/27/20 12:53 AM, Christoph Hellwig wrote: > On Wed, Feb 26, 2020 at 08:58:46AM -0700, Jens Axboe wrote: >> Yeah, should probably be a RWF_ flag instead, and a 64-bit SQE field >> for the PI data. The 'last iovec is PI' is kind of icky. > > Abusing an iovec (although I though of the first once when looking > into it) looks really horrible, but has two huge advantages: > > - it doesn't require passing another argument all the way down > the I/O stack > - it works with all the vectored interfaces that take a flag > argument, so not just io_uring, but also preadv2/pwritev2 and aio. > And while I don't care too much about the last I think preadv2 > and pwritev2 are valuable to support. > Indeed, actually the 'last iovec is PI' idea was learned from Darrick's original patch which support PI passthrough via aio. https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg27537.html