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Thu, 16 Feb 2023 16:13:52 -0800 (PST) Date: Thu, 16 Feb 2023 19:13:51 -0500 From: Mike Snitzer To: Uday Shankar Message-ID: References: <20230215201507.494152-1-ushankar@purestorage.com> <20230216192702.GA801590@dev-ushankar.dev.purestorage.com> MIME-Version: 1.0 In-Reply-To: <20230216192702.GA801590@dev-ushankar.dev.purestorage.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Subject: Re: [dm-devel] blk-mq: enforce op-specific segment limits in blk_insert_cloned_request X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Christoph Hellwig , Jens Axboe , dm-devel@redhat.com, linux-block@vger.kernel.org, Alasdair Kergon Errors-To: dm-devel-bounces@redhat.com Sender: "dm-devel" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Feb 16 2023 at 2:27P -0500, Uday Shankar wrote: > On Wed, Feb 15, 2023 at 10:09:36PM -0800, Christoph Hellwig wrote: > > I'd just remove the debug check entirely > > Older kernels have these checks in a separate function called > blk_cloned_rq_check_limits, which carries the following comment: > > /** > * blk_cloned_rq_check_limits - Helper function to check a cloned request > * for the new queue limits > * @q: the queue > * @rq: the request being checked > * > * Description: > * @rq may have been made based on weaker limitations of upper-level queues > * in request stacking drivers, and it may violate the limitation of @q. > * Since the block layer and the underlying device driver trust @rq > * after it is inserted to @q, it should be checked against @q before > * the insertion using this generic function. > * > * Request stacking drivers like request-based dm may change the queue > * limits when retrying requests on other queues. Those requests need > * to be checked against the new queue limits again during dispatch. > */. > > Is this concern no longer relevant? Still relevant. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel 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 6F58EC636CC for ; Fri, 17 Feb 2023 00:14:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229678AbjBQAOl (ORCPT ); Thu, 16 Feb 2023 19:14:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229505AbjBQAOk (ORCPT ); Thu, 16 Feb 2023 19:14:40 -0500 Received: from mail-qt1-f175.google.com (mail-qt1-f175.google.com [209.85.160.175]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0D113234FA for ; Thu, 16 Feb 2023 16:13:54 -0800 (PST) Received: by mail-qt1-f175.google.com with SMTP id f10so4036537qtv.1 for ; Thu, 16 Feb 2023 16:13:54 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=6kImKyTnUFlrsbZ3cxw052u3lsceBXaXeoQEmfLR09Q=; b=cjo2AHCbwPMfZ0b+ufm2xue4qk2YfNIrAkDkfg7soI3RmFZT/+FkzoKxLHgs0TS9Q8 jTE4qi8sDNhljRvW27V0PPfnxhJvZR2OHK49mHO3W7HkOswhEBujot7/TNCAENRKYKix MLAsE04T+T57e9hb17YBrrqPleExNB/LRjY5cYXIHL8G2uvMb6v+j3tPiO03g4b/v5ud viSRmm5WU4cqE4pTd3AMF+u/OZMQjoZDLQz3sK452V1kcCzzenuRF2tH2xI+thUdTo4Z b4/Gj6LsBC4QEZOuVhGl5Oq90v1kF393PriAQJiR4zmZwoFlIcqtUAnImOT/ukuGy77h FM3w== X-Gm-Message-State: AO0yUKU7kk/i1fyXMcJOMYVoywx2AMbZgSvsN6Jm4SnOqFFr/0qA3K3I aEQyCmMBgYYIHhKjtuGyxj61 X-Google-Smtp-Source: AK7set8j9cfHfcZl/vzGU/yVM8ih72maPo/h2Vl1C+ebpdpF9rGGVgryO/199T+35W3ZyOZr6LNmWA== X-Received: by 2002:ac8:5f4a:0:b0:3b9:bc8c:c1f8 with SMTP id y10-20020ac85f4a000000b003b9bc8cc1f8mr8029510qta.3.1676592833020; Thu, 16 Feb 2023 16:13:53 -0800 (PST) Received: from localhost ([87.249.138.162]) by smtp.gmail.com with ESMTPSA id 18-20020a370312000000b0071b1fe18746sm2260140qkd.63.2023.02.16.16.13.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Feb 2023 16:13:52 -0800 (PST) Date: Thu, 16 Feb 2023 19:13:51 -0500 From: Mike Snitzer To: Uday Shankar Cc: Christoph Hellwig , Jens Axboe , linux-block@vger.kernel.org, dm-devel@redhat.com, Alasdair Kergon Subject: Re: blk-mq: enforce op-specific segment limits in blk_insert_cloned_request Message-ID: References: <20230215201507.494152-1-ushankar@purestorage.com> <20230216192702.GA801590@dev-ushankar.dev.purestorage.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230216192702.GA801590@dev-ushankar.dev.purestorage.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Feb 16 2023 at 2:27P -0500, Uday Shankar wrote: > On Wed, Feb 15, 2023 at 10:09:36PM -0800, Christoph Hellwig wrote: > > I'd just remove the debug check entirely > > Older kernels have these checks in a separate function called > blk_cloned_rq_check_limits, which carries the following comment: > > /** > * blk_cloned_rq_check_limits - Helper function to check a cloned request > * for the new queue limits > * @q: the queue > * @rq: the request being checked > * > * Description: > * @rq may have been made based on weaker limitations of upper-level queues > * in request stacking drivers, and it may violate the limitation of @q. > * Since the block layer and the underlying device driver trust @rq > * after it is inserted to @q, it should be checked against @q before > * the insertion using this generic function. > * > * Request stacking drivers like request-based dm may change the queue > * limits when retrying requests on other queues. Those requests need > * to be checked against the new queue limits again during dispatch. > */. > > Is this concern no longer relevant? Still relevant.