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=-1.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 EAE1EC07E85 for ; Fri, 7 Dec 2018 03:34:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F62A2082D for ; Fri, 7 Dec 2018 03:34:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="x0J3U+zj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9F62A2082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726047AbeLGDei (ORCPT ); Thu, 6 Dec 2018 22:34:38 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:37118 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbeLGDei (ORCPT ); Thu, 6 Dec 2018 22:34:38 -0500 Received: by mail-pl1-f195.google.com with SMTP id b5so1162330plr.4 for ; Thu, 06 Dec 2018 19:34:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=wYYVI1ZQvqHTNSyFIOkP+j90ajmQeZj7B5YbyYFFvhM=; b=x0J3U+zjEMawL0idEB7cFaja3XK2XoF2zzC/KP1vwVUpkMVwW2wYKtBEmYcgzzsGpQ 5+zjX/Ss1oljMDkmzqq3vloVVYNJ+9rHDKwJ0miw8lXdFjB9n4cx+rwleVbjkAnqQHb/ HrwHyMW+/Ku9qpYrLA43vjkOZNo3l5Wz3VxQygMe0CfNt9epRbHc9BCfQcQHxKgdEvQQ N/S5qFwA+2iogITUoa00zzqnuyPMX2kZF2ZOGL6jrbhu9UXHfNP/FVbp3QuTeTkwfjdM nfzzaOMAblyD007lq4PhaZOBXiYEW4Oc4gH/Q+5PBpe5h6/pxAxEOHTrFS+hVD8YYwES fjOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=wYYVI1ZQvqHTNSyFIOkP+j90ajmQeZj7B5YbyYFFvhM=; b=t7HUb3tbOlQ+eQM+nohr9WPHrqlDEvmLKY0UEZva1+Q+jUuaO6DHwr0sxqBjvWnkPi 0lvYPNJCIxCYymN7lTHwThfPbekrzO2Vc3F0qt/M/6kJlu8xUvrD+sJQ80vMOhVFBKM2 sn74oJTGdKOD38jQB5c5F9z/ggm6A1QgjmNn0ccYGlMCzNMiKyccdI9ToRqhud2rbNyx w4/XubEUZQjWwiRKjZeydFavHShE7eQftwCoIwWBMoG1JdAxQA8YfobU7+eyhCyqOOm5 N+W0PsjYddldlhixeNWBshBXs/M4Vc7Pn0+V9ytjtBqqiMMfIVVTNuD13kA3JwXcs9rh DA8A== X-Gm-Message-State: AA+aEWYAytTBJHTZhZEYipKNlqQ/skagOxPFK68mVFr7PRmU7XtBBT4a qPSzeGlgXjO6maW52IxmaA9kjOAcmF0= X-Google-Smtp-Source: AFSGD/XlZ25pIYCgTUW0+pWL77cq782G/X2/H4chWFbnSHZSdfEHVSVk6LXwR0+JYqiL/Hb76iQOxg== X-Received: by 2002:a17:902:3064:: with SMTP id u91mr583616plb.325.1544153678007; Thu, 06 Dec 2018 19:34:38 -0800 (PST) Received: from [192.168.1.121] (66.29.188.166.static.utbb.net. [66.29.188.166]) by smtp.gmail.com with ESMTPSA id w11sm1792963pgk.16.2018.12.06.19.34.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Dec 2018 19:34:37 -0800 (PST) Subject: Re: [PATCH V11 0/4] blk-mq: refactor code of issue directly From: Jens Axboe To: "jianchao.wang" Cc: ming.lei@redhat.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1544152185-32667-1-git-send-email-jianchao.w.wang@oracle.com> <0adf3419-bcce-93d8-51fb-aee7cbb5ae17@oracle.com> <16205e68-aa5e-c59d-364e-4164a0e51dc7@kernel.dk> Message-ID: Date: Thu, 6 Dec 2018 20:34:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <16205e68-aa5e-c59d-364e-4164a0e51dc7@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12/6/18 8:32 PM, Jens Axboe wrote: > On 12/6/18 8:26 PM, jianchao.wang wrote: >> >> >> On 12/7/18 11:16 AM, Jens Axboe wrote: >>> On 12/6/18 8:09 PM, Jianchao Wang wrote: >>>> Hi Jens >>>> >>>> Please consider this patchset for 4.21. >>>> >>>> It refactors the code of issue request directly to unify the interface >>>> and make the code clearer and more readable. >>>> >>>> This patch set is rebased on the recent for-4.21/block and add the 1st >>>> patch which inserts the non-read-write request to hctx dispatch >>>> list to avoid to involve merge and io scheduler when bypass_insert >>>> is true, otherwise, inserting is ignored, BLK_STS_RESOURCE is returned >>>> and the caller will fail forever. >>>> >>>> The 2nd patch refactors the code of issue request directly to unify the >>>> helper interface which could handle all the cases. >>>> >>>> The 3rd patch make blk_mq_sched_insert_requests issue requests directly >>>> with 'bypass' false, then it needn't to handle the non-issued requests >>>> any more. >>>> >>>> The 4th patch replace and kill the blk_mq_request_issue_directly. >>> >>> Sorry to keep iterating on this, but let's default to inserting to >>> the dispatch list if we ever see busy from a direct dispatch. I'm fine >>> with doing that for 4.21, as suggested by Ming, I just didn't want to >>> fiddle with it for 4.20. This will prevent any merging on the request >>> going forward, which I think is a much safer default. >>> >>> You do this already for some cases. Let's do it unconditionally for >>> a request that was ever subjected to ->queue_rq() and we didn't either >>> error or finish after the fact. >>> >> I have done it in this version if I get your point correctly. >> Please refer to the following fragment in the 2nd patch. >> >> + /* >> + * If the request is issued unsuccessfully with >> + * BLK_STS_DEV_RESOURCE or BLK_STS_RESOURCE, insert >> + * the request to hctx dispatch list due to attached >> + * lldd resource. >> + */ >> + force = true; >> + ret = __blk_mq_issue_directly(hctx, rq, cookie, last); >> +out_unlock: >> + hctx_unlock(hctx, srcu_idx); >> +out: >> + switch (ret) { >> + case BLK_STS_OK: >> + break; >> + case BLK_STS_DEV_RESOURCE: >> + case BLK_STS_RESOURCE: >> + if (force) { >> + blk_mq_request_bypass_insert(rq, run_queue); >> + ret = bypass ? BLK_STS_OK : ret; >> + } else if (!bypass) { >> + blk_mq_sched_insert_request(rq, false, >> + run_queue, false); >> + } >> + break; >> + default: > > You are right, I missed that you set force = true before doing the > issue. So this looks good to me! I applied your series. With this, we should be good to remove the REQ_NOMERGE logic that was added for the corruption case, and the blk_rq_can_direct_dispatch() as well? -- Jens Axboe