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Mon, 05 Oct 2026 04:44:59 -0700 (PDT) Received: from [10.41.30.1] ([161.12.45.16]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48c62270751sm3087877f8f.13.2026.10.05.04.44.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 05 Oct 2026 04:44:58 -0700 (PDT) Message-ID: Date: Mon, 5 Oct 2026 12:44:55 +0100 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 02/13] iov_iter: add iterator type for dmabuf maps 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: <74a9d65f5c4f9acce5f57ad5921a9fadc6eda712.1790602223.git.asml.silence@gmail.com> <20261005091008.GA10727@lst.de> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <20261005091008.GA10727@lst.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/5/26 10:10, Christoph Hellwig wrote: > On Mon, Sep 28, 2026 at 02:32:18PM +0100, Pavel Begunkov wrote: >> Introduce a new iterator type for dmabuf maps. The map in an opaque >> object with internals and format specific to the subsystem / driver, and >> only it can use that subsystem / driver for issuing IO. The task of the >> middle layers is to pass the map / iterator further down, maybe doing >> basic splitting and length checking. The iterator can only be used by >> operations of the file the associated map was created for. >> >> Suggested-by: Keith Busch >> Reviewed-by: Christoph Hellwig >> Signed-off-by: Pavel Begunkov > > FYI, I think the Sashiko complaint about iterate_and_advance2 > is correct here. We don't really hit that in the series, but leaving > iov_iter methods partially implemented and fall through to others > seems dangerous. At minimum that needs a WARN_ON to catch that case. v7 already covers iterate_and_advance2(). It complains about iterate_and_advance_kernel() but there are many types this one doesn't support. -- Pavel Begunkov