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Tue, 17 Aug 2021 10:14:29 -0700 (PDT) To: SelvaKumar S , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org 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> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-loop: dm-devel@redhat.com Cc: Mike Snitzer , Greg Kroah-Hartman , djwong@kernel.org, dm-devel@redhat.com, hch@lst.de, agk@redhat.com, linux-scsi@vger.kernel.org, nitheshshetty@gmail.com, willy@infradead.org, nj.shetty@samsung.com, kch@kernel.org, selvajove@gmail.com, mpatocka@redhat.com, javier.gonz@samsung.com, kbusch@kernel.org, axboe@kernel.dk, damien.lemoal@wdc.com, joshi.k@samsung.com, "Martin K. Petersen" , linux-api@vger.kernel.org, johannes.thumshirn@wdc.com, linux-fsdevel@vger.kernel.org, joshiiitr@gmail.com, asml.silence@gmail.com Subject: Re: [dm-devel] [PATCH 3/7] block: copy offload support infrastructure X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" 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. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel