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[82.132.213.197]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c2a9c5baa1bsm93202166b.39.2026.09.22.06.54.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Sep 2026 06:54:39 -0700 (PDT) Message-ID: Date: Tue, 22 Sep 2026 14:54:25 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 04/13] block: introduce dma map backed bio type To: Christoph Hellwig Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Keith Busch , Sagi Grimberg , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Jens Axboe , Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Matthew Brost , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , dm-devel@lists.linux.dev References: <20260922131610.GA30468@lst.de> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20260922131610.GA30468@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_065442_724423_364764AE X-CRM114-Status: GOOD ( 16.16 ) X-Mailman-Approved-At: Tue, 22 Sep 2026 21:56:25 -0700 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 9/22/26 14:16, Christoph Hellwig wrote: > On Mon, Sep 21, 2026 at 02:38:48PM +0100, Pavel Begunkov wrote: >> Premapped buffers don't require a generic bio_vec since these have >> already been dma mapped. Repurpose the bi_io_vec space to strore dmabuf > > s/strore/store/ > > Can you please expland on the splitting considerations a bit? Preferably > both in a comment for the details, and in the commit log for how we > arrived at them and why they are fine for now? I'll add something to the commit log, but not sure which specific details in comments you mean. Do you want me to expand the comment above limiting the number of segments? Maybe I should add there that it's stricter than necessary and might cause more splitting than necessary? This one: /* * Limit by the number of segments. We don't expose the underlying * mapping layout, but with a known minimum segment size, any I/O * consisting of N full segments should be able to cover at least * this much. */ -- Pavel Begunkov