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=-7.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 AF194C4320A for ; Tue, 17 Aug 2021 17:14:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 966B460FE6 for ; Tue, 17 Aug 2021 17:14:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231308AbhHQRPF (ORCPT ); Tue, 17 Aug 2021 13:15:05 -0400 Received: from mail-pj1-f43.google.com ([209.85.216.43]:52770 "EHLO mail-pj1-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229699AbhHQRPD (ORCPT ); Tue, 17 Aug 2021 13:15:03 -0400 Received: by mail-pj1-f43.google.com with SMTP id nt11so152347pjb.2; Tue, 17 Aug 2021 10:14:30 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=v2ezKXtmZ+KjzYhpA8Y6VRyR3KOD/971FoOogNR18Hs=; b=AH0Pf/fxVX60UAFVupMs2HrhXm/SeXCyGTdjRPsamQF/3aZsZHK1c7X3oF1ccKup9m 8X/i722eoiiGnVAkeabMka6Odu0OIJNmwd0ztRKT+7r0qN13Bo9dMzsl3T88K1EN8gws 33lbu7QGIcVeZaFNUXE2DLXd/4/ToB1oNXsVNQokhNwjjtVuwtXy0q2TYhGk4QINv3vX QblcpR+ujJ3/FdzXbje5uftWevEyBr+5XdJFukmMhtjIdtulZp8KDotYRjFfZDcO9XRj cB8PyXuAXUOMBPOj1vFAneMYuNHMfQUbbxhl5bjFnCxOeywjADUcP3l9AZUmpI6J/B0p zR4g== X-Gm-Message-State: AOAM531p4Ei5/9qdGJx2W266mjHtPG+KAvjWIX/3PSsN/9iVV+eSYlM+ mZ05yLWtLz1mP8TITDHeCiI= X-Google-Smtp-Source: ABdhPJxyRl0ks4xxfdYxuKBl/CqSpHH1tc/kfe77IZhXj/2ic6tgtgAm7bavNRKoa2tEHngKC7nW9Q== X-Received: by 2002:a17:90a:3b4b:: with SMTP id t11mr4532753pjf.182.1629220470271; Tue, 17 Aug 2021 10:14:30 -0700 (PDT) Received: from bvanassche-linux.mtv.corp.google.com ([2620:15c:211:201:ae3f:1e44:e6d0:4a44]) by smtp.gmail.com with ESMTPSA id x13sm2822931pjh.30.2021.08.17.10.14.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Aug 2021 10:14:29 -0700 (PDT) Subject: Re: [PATCH 3/7] block: copy offload support infrastructure To: SelvaKumar S , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org Cc: linux-api@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, kbusch@kernel.org, axboe@kernel.dk, damien.lemoal@wdc.com, asml.silence@gmail.com, johannes.thumshirn@wdc.com, hch@lst.de, willy@infradead.org, kch@kernel.org, martin.petersen@oracle.com, mpatocka@redhat.com, djwong@kernel.org, snitzer@redhat.com, agk@redhat.com, selvajove@gmail.com, joshiiitr@gmail.com, nj.shetty@samsung.com, nitheshshetty@gmail.com, joshi.k@samsung.com, javier.gonz@samsung.com, Mike Snitzer , Greg Kroah-Hartman , "Martin K. Petersen" References: <20210817101423.12367-1-selvakuma.s1@samsung.com> <20210817101423.12367-4-selvakuma.s1@samsung.com> From: Bart Van Assche Message-ID: Date: Tue, 17 Aug 2021 10:14:27 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210817101423.12367-4-selvakuma.s1@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 8/17/21 3:14 AM, SelvaKumar S wrote: > Introduce REQ_OP_COPY, a no-merge copy offload operation. Create > bio with control information as payload and submit to the device. > Larger copy operation may be divided if necessary by looking at device > limits. REQ_OP_COPY(19) is a write op and takes zone_write_lock when > submitted to zoned device. > Native copy offload is not supported for stacked devices. Using a single operation for copy-offloading instead of separate operations for reading and writing is fundamentally incompatible with the device mapper. I think we need a copy-offloading implementation that is compatible with the device mapper. Storing the parameters of the copy operation in the bio payload is incompatible with the current implementation of bio_split(). In other words, I think there are fundamental problems with this patch series. Bart.