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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 84026C27C4F for ; Wed, 26 Jun 2024 05:22:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=7GOq09YPV5WKvKiqDxdCpSznJOrv/nBzOVzuKrdTRsk=; b=fM10S79MkAD5nXy2S3r3ay3L+p TUvt3kG7rUhxqAE49XYPZFjW/6EkTw3e2KqmGyYGkMHC1OWQjHlvhAeuKPBGb5zPPowFcufMSKc7x qgIricf4ii9VzuYFs7vN9KR//C7i26R2DCv3i2L1AnnLwUWfUH6zS9/zN7iI6Sqr2UBzhl84frL/N Oqr5hQy8SFfvcK6dZTeydxF6pSHFgIdtthbsiC1Hv6pm6aMNSyEvp1MOLY6wN8Tg6nW0rnrfCr8aN uHPnaLKv31WMCa1xugEeF5vvUL4N8ybdbsa6TuJNLlCdbTE02UynBU6RseR1mLRweQ7989rXgPC8t kXaWzNBA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sML7I-00000005RkG-16Me; Wed, 26 Jun 2024 05:22:48 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sML7D-00000005Rht-3b0Q for linux-nvme@lists.infradead.org; Wed, 26 Jun 2024 05:22:46 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 04B43227A87; Wed, 26 Jun 2024 07:22:39 +0200 (CEST) Date: Wed, 26 Jun 2024 07:22:38 +0200 From: Christoph Hellwig To: Damien Le Moal Cc: Bart Van Assche , Nitesh Shetty , Christoph Hellwig , Jens Axboe , Jonathan Corbet , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Keith Busch , Sagi Grimberg , Chaitanya Kulkarni , Alexander Viro , Christian Brauner , Jan Kara , martin.petersen@oracle.com, david@fromorbit.com, hare@suse.de, damien.lemoal@opensource.wdc.com, anuj20.g@samsung.com, joshi.k@samsung.com, nitheshshetty@gmail.com, gost.dev@samsung.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, dm-devel@lists.linux.dev, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v20 02/12] Add infrastructure for copy offload in block and request layer. Message-ID: <20240626052238.GC21996@lst.de> References: <20240604044042.GA29094@lst.de> <4ffad358-a3e6-4a88-9a40-b7e5d05aa53c@acm.org> <20240605082028.GC18688@lst.de> <6679526f.170a0220.9ffd.aefaSMTPIN_ADDED_BROKEN@mx.google.com> <4ea90738-afd1-486c-a9a9-f7e2775298ff@acm.org> <05c7c08d-f512-4727-ae3c-aba6e8f2973f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <05c7c08d-f512-4727-ae3c-aba6e8f2973f@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240625_222244_108049_A10D9148 X-CRM114-Status: GOOD ( 13.93 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jun 26, 2024 at 06:18:18AM +0900, Damien Le Moal wrote: > > DM can deal with "abnormal" BIOs on its own. There is code for that. > See is_abnormal_io() and __process_abnormal_io(). Sure, that will need more code > compared to a bio sector+size based simple split, but I do not think it is a big > deal given the potential benefits of the offloading. It's not just dm. You also need it in the partition remapping code (mandatory), md (nice to have), etc. And then we have the whole mess of what is in the payload for the I/O stack vs what is in the payload for the on the wire protocol, which will have different formatting and potentially also different sizes.