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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 99E65C54EE9 for ; Tue, 20 Sep 2022 05:03:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229990AbiITFDQ (ORCPT ); Tue, 20 Sep 2022 01:03:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229588AbiITFDN (ORCPT ); Tue, 20 Sep 2022 01:03:13 -0400 Received: from out199-18.us.a.mail.aliyun.com (out199-18.us.a.mail.aliyun.com [47.90.199.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0031159244; Mon, 19 Sep 2022 22:03:11 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=ziyangzhang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VQHRtDK_1663650186; Received: from 30.97.56.91(mailfrom:ZiyangZhang@linux.alibaba.com fp:SMTPD_---0VQHRtDK_1663650186) by smtp.aliyun-inc.com; Tue, 20 Sep 2022 13:03:07 +0800 Message-ID: Date: Tue, 20 Sep 2022 13:03:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [PATCH V3 5/7] ublk_drv: consider recovery feature in aborting mechanism Content-Language: en-US To: Ming Lei Cc: axboe@kernel.dk, xiaoguang.wang@linux.alibaba.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, joseph.qi@linux.alibaba.com References: <20220913041707.197334-1-ZiyangZhang@linux.alibaba.com> <20220913041707.197334-6-ZiyangZhang@linux.alibaba.com> <9a682fac-f022-1f4d-5c2c-e1f0a84746d8@linux.alibaba.com> <64492fad-e14a-c647-b490-cd1f53a475a8@linux.alibaba.com> <5af80188-c904-635a-242e-4bb1cd7f2e01@linux.alibaba.com> From: Ziyang Zhang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/9/20 12:49, Ming Lei wrote: > On Tue, Sep 20, 2022 at 12:39:31PM +0800, Ziyang Zhang wrote: >> On 2022/9/20 12:01, Ming Lei wrote: >>> On Tue, Sep 20, 2022 at 11:24:12AM +0800, Ziyang Zhang wrote: >>>> On 2022/9/20 11:04, Ming Lei wrote: >>>>> On Tue, Sep 20, 2022 at 09:49:33AM +0800, Ziyang Zhang wrote: >>>>> >>>>> Follows the delta patch against patch 5 for showing the idea: >>>>> >>>>> >>>>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >>>>> index 4409a130d0b6..60c5786c4711 100644 >>>>> --- a/drivers/block/ublk_drv.c >>>>> +++ b/drivers/block/ublk_drv.c >>>>> @@ -656,7 +656,8 @@ static void ublk_complete_rq(struct request *req) >>>>> * Also aborting may not be started yet, keep in mind that one failed >>>>> * request may be issued by block layer again. >>>>> */ >>>>> -static void __ublk_fail_req(struct ublk_io *io, struct request *req) >>>>> +static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io, >>>>> + struct request *req) >>>>> { >>>>> WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE); >>>>> >>>>> @@ -667,7 +668,10 @@ static void __ublk_fail_req(struct ublk_io *io, struct request *req) >>>>> req->tag, >>>>> io->flags); >>>>> io->flags |= UBLK_IO_FLAG_ABORTED; >>>>> - blk_mq_end_request(req, BLK_STS_IOERR); >>>>> + if (ublk_queue_can_use_recovery_reissue(ubq)) >>>>> + blk_mq_requeue_request(req, false); >>>> >>>> Here is one problem: >>>> We reset io->flags to 0 in ublk_queue_reinit() and it is called before new >>> >>> As we agreed, ublk_queue_reinit() will be moved to ublk_ch_release(), when there isn't >>> any inflight request, which is completed by either ublk server or __ublk_fail_req(). >>> >>> So clearing io->flags isn't related with quisceing device. >>> >>>> ubq_daemon with FETCH_REQ is accepted. ublk_abort_queue() is not protected with >>>> ub_mutex and it is called many times in monitor_work. So same rq may be requeued >>>> multiple times. >>> >>> UBLK_IO_FLAG_ABORTED is set for the slot, so one req is only ended or >>> requeued just once. >> >> Yes, we can move ublk_queue_reinit() into ublk_ch_release(), but monitor_work is scheduled >> periodically so ublk_abort_queue() is called multiple times. As ublk_queue_reinit() clear >> io->flags, ublk_abort_queue() can requeue the same rq twice. Note that monitor_work can be >> scheduled after ublk_ch_release(). > > No, monitor work is supposed to be shutdown after in-flight requests are > drained. Let's add cancel_delayed_work_sync(&ub->monitor_work) in ublk_ch_release(). monitor_work should not be scheduled after ub's state is QUIESCED. Regards, Zhang.