Re: enable iomap dio write completions from interrupt context v2

[Christian Brauner <brauner@kernel.org>]

On Thu, 13 Nov 2025 18:06:25 +0100, Christoph Hellwig wrote:
> Currently iomap defers all write completions to interrupt context.  This
> was based on my assumption that no one cares about the latency of those
> to simplify the code vs the old direct-io.c.  It turns out someone cared,
> as Avi reported a lot of context switches with ScyllaDB, which at least
> in older kernels with workqueue scheduling issues caused really high
> tail latencies.
> 
> [...]

Applied to the vfs-6.19.iomap branch of the vfs/vfs.git tree.
Patches in the vfs-6.19.iomap branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-6.19.iomap

[1/5] fs, iomap: remove IOCB_DIO_CALLER_COMP
      https://git.kernel.org/vfs/vfs/c/56749ed317e2
[2/5] iomap: always run error completions in user context
      https://git.kernel.org/vfs/vfs/c/222f2c7c6d14
[3/5] iomap: rework REQ_FUA selection
      https://git.kernel.org/vfs/vfs/c/845c50436431
[4/5] iomap: support write completions from interrupt context
      https://git.kernel.org/vfs/vfs/c/a4ae47e5d2bc
[5/5] iomap: invert the polarity of IOMAP_DIO_INLINE_COMP
      https://git.kernel.org/vfs/vfs/c/65a466aef147