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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-496c45b1c2asm171605965e9.5.2026.07.29.10.46.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jul 2026 10:46:07 -0700 (PDT) Message-ID: <5afa3726-6c15-41c8-af19-766eb76b4b46@gmail.com> Date: Wed, 29 Jul 2026 18:45:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 14/14] io_uring/rsrc: add dmabuf backed registered buffers To: Anuj gupta Cc: Anuj Gupta/Anuj Gupta , Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Alexander Viro , Christian Brauner , Andrew Morton , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Nitesh Shetty , Kanchan Joshi , Jason Gunthorpe , Damien Le Moal , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Benjamin Marzinski , David Sterba , Ilya Dryomov , dm-devel@lists.linux.dev, nvdimm@lists.linux.dev, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org References: <26dcd0ae5c87a3ada5710b14b6894ef343cec6fe.1785274111.git.asml.silence@gmail.com> <583fdfb2-5368-467f-a388-6d388859c995@samsung.com> <0df2f832-e8a8-4fdd-a5b6-e08657c2891f@gmail.com> Content-Language: en-US From: Pavel Begunkov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260729_104610_403876_C478D8C5 X-CRM114-Status: GOOD ( 13.29 ) X-Mailman-Approved-At: Thu, 30 Jul 2026 22:07:00 -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 7/29/26 17:52, Anuj gupta wrote: > On Wed, Jul 29, 2026 at 7:37 PM Pavel Begunkov wrote: >>>> +static int io_import_dmabuf(struct io_kiocb *req, >>>> + int ddir, struct iov_iter *iter, >>>> + struct io_mapped_ubuf *imu, >>>> + size_t len, size_t offset, >>>> + unsigned issue_flags) >>>> +{ >>>> + struct io_regbuf_dma *db = imu->priv; >>>> + struct dma_buf_io_map *map; >>>> + >>>> + if (!IS_ENABLED(CONFIG_DMA_SHARED_BUFFER)) >>>> + return -EOPNOTSUPP; >>>> + if (!len) >>>> + return -EFAULT; >>>> + if (req->file != db->target_file) >>>> + return -EBADF; >>>> + >>>> + if (req->flags & REQ_F_DROP_DMABUF) { >>>> + map = req->dmabuf_map; >>>> + goto init_iter; >>>> + } >>> >>> O_DIRECT is checked only during registration; we should recheck >>> (file->f_flags & O_DIRECT) per request. >> >> Nobody should be able to clear O_DIRECT, unless I missed something? >> And fwiw, io_uring wouldn't be the right place to do it. >> > > fcntl(fd, F_SETFL, flags & ~O_DIRECT) on an already registered, already > open fd succeeds. The consequence is that subsequent I/Os switch to Very exciting. > buffered I/O and cause silent data loss. Something on this path needs > to reject this combination. Yeah, I'll fix it, thanks -- Pavel Begunkov