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bh=0ilKtUDLU3xGxduLonN3eGibnQvh68iPK6xSKyYUOoU=; b=b/nuvRU2/IoozMkhu3mIHfAyEl RKkQiEF+lhJUc10muHa6qXv1EXRebIM1fQTmhK2lF+fL0DqGhiHbG4ZWjR5LIgs9CFo8Z3Y2ZV1kY j/70R4chy02UprCaSQIywOcRQF1wRLUZKZsIERdMGYzlFNFhpaHyFO+2cigQZViw4farcxUf6TbYB UABDK7RtyPFSpYwhJesGSSkdH17qkYOL8VWFgqJ3baziBIGFJ3vfi1CeVThA9FDkTm2kE0stGx7kH ei0r1f5w7M9vLrL8bhmfvoCd9UFQTdw0WpoBSeeI+Q+VPjNp9p02KiaKHDf8EHdNKmmbHC63UWqS4 NnPSoXnA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uR2LU-00000003QVL-1zRf; Mon, 16 Jun 2025 05:25:24 +0000 Date: Sun, 15 Jun 2025 22:25:24 -0700 From: Christoph Hellwig To: wangtao Cc: Christoph Hellwig , Christian =?iso-8859-1?Q?K=F6nig?= , "sumit.semwal@linaro.org" , "kraxel@redhat.com" , "vivek.kasireddy@intel.com" , "viro@zeniv.linux.org.uk" , "brauner@kernel.org" , "hughd@google.com" , "akpm@linux-foundation.org" , "amir73il@gmail.com" , "benjamin.gaignard@collabora.com" , "Brian.Starkey@arm.com" , "jstultz@google.com" , "tjmercier@google.com" , "jack@suse.cz" , "baolin.wang@linux.alibaba.com" , "linux-media@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linaro-mm-sig@lists.linaro.org" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "wangbintian(BintianWang)" , yipengxiang , liulu 00013167 , hanfeng 00012985 Subject: Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range Message-ID: References: <20250603095245.17478-1-tao.wangtao@honor.com> <09c8fb7c-a337-4813-9f44-3a538c4ee8b1@amd.com> <5d36abace6bf492aadd847f0fabc38be@honor.com> <761986ec0f404856b6f21c3feca67012@honor.com> <34c2dbc06d074ffbb8f920418636bafc@honor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <34c2dbc06d074ffbb8f920418636bafc@honor.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-Stat-Signature: gpnmh38p656r6nocxkhb57nztnnjdkyr X-Rspamd-Queue-Id: 9C2F7180003 X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1750051533-340878 X-HE-Meta: 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 uRJ32Ig8 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 13, 2025 at 09:33:55AM +0000, wangtao wrote: > > > > > On Mon, Jun 09, 2025 at 09:32:20AM +0000, wangtao wrote: > > > Are you suggesting adding an ITER_DMABUF type to iov_iter, > > > > Yes. > > May I clarify: Do all disk operations require data to pass through > memory (reading into memory or writing from memory)? In the block layer, > the bio structure uses bio_iov_iter_get_pages to convert iter_type > objects into memory-backed bio_vec representations. > However, some dmabufs are not memory-based, making page-to-bio_vec > conversion impossible. This suggests adding a callback function in > dma_buf_ops to handle dmabuf- to-bio_vec conversion. bios do support PCI P2P tranfers. This could be fairly easily extended to other peer to peer transfers if we manage to come up with a coherent model for them. No need for a callback.