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 D0129C32771 for ; Mon, 26 Sep 2022 17:19:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230354AbiIZRS7 (ORCPT ); Mon, 26 Sep 2022 13:18:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230462AbiIZRSj (ORCPT ); Mon, 26 Sep 2022 13:18:39 -0400 Received: from mail-io1-xd2b.google.com (mail-io1-xd2b.google.com [IPv6:2607:f8b0:4864:20::d2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 486ABE1098 for ; Mon, 26 Sep 2022 09:32:45 -0700 (PDT) Received: by mail-io1-xd2b.google.com with SMTP id h194so5680656iof.4 for ; Mon, 26 Sep 2022 09:32:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date; bh=BxnsyrNOfRRvN4ZxwiPkZaVoZKcCqMXtLHTaeCguwX4=; b=KBC9QeNVMBnQErEdrDFPIQawHLknQnGE6SAYOpJC3hxSMiGNYPpGNkAJ/FhdC/ClCg tc1kiMOrX5LKuH1dYd29r02uKM0gtzoAguu1QcX3qOhLEazXtNHoJ65yGmqENYoHuwtm 6056Mt/ITJf9IEt5SohjtVrsCS2hIRg07g1QQRUU0BJEk1fSqr4U/6xXz8zIFQ8efmDR iHvywvdbZIM39V1jNyxhAw27EDk4eCe4mpFQio6WcwZCxMc3v3nWtsYgC5PMhxSwujy1 zp8qsFkMt0ux5iYPgioDdgtXbBQXz2vnEjDAt+xazrVZQ1drrCo4XcLyBfO+GvlC3BhH xWPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date; bh=BxnsyrNOfRRvN4ZxwiPkZaVoZKcCqMXtLHTaeCguwX4=; b=7Md+5hnGn2fDkqkKqVF/zI6517Ci4yTVdQBpc1E0uFsmrzU5k8wkVd9ovcKMQuNRs+ HvoKyBNBiCUV3qzvh2XSa925tr9FWMPHU3HGinPmRt+WJPzJ/QxDm+hicFKZeSxq0MfV 3yB2QLrcE1Silj1S+o2VrgR8x6bfqocd/y5uaBPDY9hu8ZdUSSGJJQjSjCGFaS2PkQAG dglHo3RSYj3MV6LxVLkzBC8yq/okDCuixfXwNJV9xDffzLGPvHo3ZOvRWUIJjBdtmlFf jsocWtPW7i8cbw/XlFxbnvcekASD6SIsnCzq90xWyRdtnrN1AbCklEI46YxPuVwLv9we O7Lg== X-Gm-Message-State: ACrzQf3w45+vQjw/x8BNmks/c7HhfQ6axWb7FZoT0Ai2csjXX0JrZVls KinDVK00FOCxsmasB+4zd5QGcw== X-Google-Smtp-Source: AMsMyM7hRmBGrNShU4EhDsmsaeaEdPVCEoPbLI2JqvhBfa9c1h1+675I8JpTEILBHkfM48YVXbJjmQ== X-Received: by 2002:a05:6638:19:b0:35a:52a2:dfbe with SMTP id z25-20020a056638001900b0035a52a2dfbemr11450888jao.213.1664209961137; Mon, 26 Sep 2022 09:32:41 -0700 (PDT) Received: from [192.168.1.94] ([207.135.234.126]) by smtp.gmail.com with ESMTPSA id h44-20020a022b2c000000b00358422fcc7bsm7194378jaa.120.2022.09.26.09.32.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 26 Sep 2022 09:32:40 -0700 (PDT) Message-ID: <2ee6a897-87e7-0592-2482-9928a9a63ff6@kernel.dk> Date: Mon, 26 Sep 2022 10:32:39 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH 1/2] block: modify blk_mq_plug() to allow only reads for zoned block devices Content-Language: en-US To: Christoph Hellwig Cc: Pankaj Raghav , linux-block@vger.kernel.org, damien.lemoal@opensource.wdc.com, gost.dev@samsung.com References: <20220925185348.120964-1-p.raghav@samsung.com> <20220925185348.120964-2-p.raghav@samsung.com> From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 9/26/22 8:43 AM, Christoph Hellwig wrote: > On Mon, Sep 26, 2022 at 08:40:54AM -0600, Jens Axboe wrote: >> On 9/26/22 8:37 AM, Christoph Hellwig wrote: >>> On Sun, Sep 25, 2022 at 08:53:46PM +0200, Pankaj Raghav wrote: >>>> Modify blk_mq_plug() to allow plugging only for read operations in zoned >>>> block devices as there are alternative IO paths in the linux block >>>> layer which can end up doing a write via driver private requests in >>>> sequential write zones. >>> >>> We should be able to plug for all operations that are not >>> REQ_OP_ZONE_APPEND just fine. >> >> Agree, I think we just want to make this about someone doing a series >> of appends. If you mix-and-match with passthrough you will have a bad >> time anyway. > > Err, sorry - what I wrote about is compelte garbage. I initially > wanted to say you can plug for REQ_OP_ZONE_APPEND just fine, and then > realized that we also want various other ones that have the write bit > set batched. So I suspect we really want to explicitly check for > REQ_OP_WRITE here. My memory was a bit hazy, since we have separate ops for the driver in/out, I think just checking for REQ_OP_WRITE is indeed the right choice. That's the single case we need to care about. -- Jens Axboe