From: Christoph Hellwig <hch@lst.de>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Anuj Gupta <anuj1072538@gmail.com>,
hch@lst.de, djwong@kernel.org, cem@kernel.org,
brauner@kernel.org, axboe@kernel.dk, linux-block@vger.kernel.org,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
joshi.k@samsung.com, anuj20.g@samsung.com, nj.shetty@samsung.com
Subject: Re: [RFC 0/4] fs: support dma-buf backed direct I/O
Date: Wed, 28 Oct 2026 17:29:00 +0100 [thread overview]
Message-ID: <20261028162900.GA22640@lst.de> (raw)
In-Reply-To: <4649a20f-aba9-418e-987f-66f21ab24410@gmail.com>
On Sun, Oct 18, 2026 at 11:18:27PM +0100, Pavel Begunkov wrote:
> file_ref_t f_ref;
> /* --- cacheline 3 boundary (192 bytes) --- */
> +
> + /*
> + * A tag representing the underlying subsystem for dma-buf I/O.
> + * See struct dma_buf_io_ctx::importer_tag.
> + */
> + unsigned long f_dma_io_tag;
> } __randomize_layout
Growing strut file into a new cacheline just for dmabufs is a no-go..
Also note that a file can be placed on multiple block devices when
using RAID or just btrfs placements (not sure about f2fs).
next prev parent reply other threads:[~2026-10-28 16:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 9:19 [RFC 0/4] fs: support dma-buf backed direct I/O Anuj Gupta
2026-10-16 9:19 ` [RFC 1/4] block: factor out bdev_init_dma_buf_io_ctx() Anuj Gupta
2026-10-16 9:23 ` Christoph Hellwig
2026-10-16 9:19 ` [RFC 2/4] block: refuse a dma-buf bio for a disk the buffer was not registered on Anuj Gupta
2026-10-16 9:24 ` Christoph Hellwig
2026-10-21 15:12 ` Pavel Begunkov
2026-10-22 13:00 ` Nitesh Shetty
2026-10-16 9:19 ` [RFC 3/4] iomap: add dma-buf direct I/O guards and registration helper Anuj Gupta
2026-10-16 9:26 ` Christoph Hellwig
2026-10-16 9:19 ` [RFC 4/4] xfs: support dma-buf registered buffers for direct I/O Anuj Gupta
2026-10-16 9:28 ` Christoph Hellwig
2026-10-17 18:19 ` Kanchan Joshi
2026-10-18 22:28 ` Pavel Begunkov
2026-10-19 10:29 ` Anuj gupta
2026-10-18 22:18 ` [RFC 0/4] fs: support dma-buf backed " Pavel Begunkov
2026-10-28 16:29 ` Christoph Hellwig [this message]
2026-10-29 11:34 ` Pavel Begunkov
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