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From: Christoph Hellwig <hch@infradead.org>
To: wangtao <tao.wangtao@honor.com>
Cc: "Christoph Hellwig" <hch@infradead.org>,
	"Christian König" <christian.koenig@amd.com>,
	"sumit.semwal@linaro.org" <sumit.semwal@linaro.org>,
	"kraxel@redhat.com" <kraxel@redhat.com>,
	"vivek.kasireddy@intel.com" <vivek.kasireddy@intel.com>,
	"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"brauner@kernel.org" <brauner@kernel.org>,
	"hughd@google.com" <hughd@google.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"amir73il@gmail.com" <amir73il@gmail.com>,
	"benjamin.gaignard@collabora.com"
	<benjamin.gaignard@collabora.com>,
	"Brian.Starkey@arm.com" <Brian.Starkey@arm.com>,
	"jstultz@google.com" <jstultz@google.com>,
	"tjmercier@google.com" <tjmercier@google.com>,
	"jack@suse.cz" <jack@suse.cz>,
	"baolin.wang@linux.alibaba.com" <baolin.wang@linux.alibaba.com>,
	"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"wangbintian(BintianWang)" <bintian.wang@honor.com>,
	yipengxiang <yipengxiang@honor.com>,
	"liulu 00013167" <liulu.liu@honor.com>,
	"hanfeng 00012985" <feng.han@honor.com>
Subject: Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range
Date: Sun, 15 Jun 2025 22:25:24 -0700	[thread overview]
Message-ID: <aE-qxK6rbvfoeBr6@infradead.org> (raw)
In-Reply-To: <34c2dbc06d074ffbb8f920418636bafc@honor.com>

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.


      reply	other threads:[~2025-06-16  5:25 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-03  9:52 [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range wangtao
2025-06-03  9:52 ` [PATCH v4 1/4] fs: allow cross-FS copy_file_range for memory file with direct I/O wangtao
2025-06-03 10:56   ` Amir Goldstein
2025-06-03 12:38     ` wangtao
2025-06-03 12:43       ` Amir Goldstein
2025-06-03  9:52 ` [PATCH v4 2/4] dmabuf: Implement copy_file_range callback for dmabuf direct I/O prep wangtao
2025-06-03 10:42   ` Christian König
2025-06-03 12:26     ` wangtao
2025-06-03 13:04   ` Christoph Hellwig
2025-06-03  9:52 ` [PATCH v4 3/4] udmabuf: Implement udmabuf direct I/O wangtao
2025-06-03  9:52 ` [PATCH v4 4/4] dmabuf:system_heap Implement system_heap dmabuf " wangtao
2025-06-03 13:00 ` [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range Christoph Hellwig
2025-06-03 13:14   ` Christian König
2025-06-03 13:19     ` Christoph Hellwig
2025-06-03 14:18       ` Christian König
2025-06-03 14:28         ` Christoph Hellwig
2025-06-03 15:55           ` Christian König
2025-06-03 16:01             ` Christoph Hellwig
2025-06-06  9:59               ` wangtao
2025-06-06  9:52       ` wangtao
2025-06-06 11:20         ` Christian König
2025-06-09  4:35           ` Christoph Hellwig
2025-06-09  9:32             ` wangtao
2025-06-10 10:52               ` Christian König
2025-06-10 13:37                 ` Christoph Hellwig
2025-06-13  9:43                   ` wangtao
2025-06-16  5:24                     ` Christoph Hellwig
2025-06-10 13:34               ` Christoph Hellwig
2025-06-13  9:33                 ` wangtao
2025-06-16  5:25                   ` Christoph Hellwig [this message]

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