linux-kernel - Re: re-enable IOCB_NOWAIT writes to files v4

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Message-ID: <20251224-zusah-emporsteigen-764a9185a0a1@brauner>
Date: Wed, 24 Dec 2025 14:11:29 +0100
From: Christian Brauner <brauner@...nel.org>
To: Christoph Hellwig <hch@....de>
Cc: Christian Brauner <brauner@...nel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	David Sterba <dsterba@...e.com>,
	Jan Kara <jack@...e.cz>,
	Mike Marshall <hubcap@...ibond.com>,
	Martin Brandenburg <martin@...ibond.com>,
	Carlos Maiolino <cem@...nel.org>,
	Stefan Roesch <shr@...com>,
	Jeff Layton <jlayton@...nel.org>,
	linux-kernel@...r.kernel.org,
	linux-btrfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	gfs2@...ts.linux.dev,
	io-uring@...r.kernel.org,
	devel@...ts.orangefs.org,
	linux-unionfs@...r.kernel.org,
	linux-mtd@...ts.infradead.org,
	linux-xfs@...r.kernel.org,
	linux-nfs@...r.kernel.org
Subject: Re: re-enable IOCB_NOWAIT writes to files v4

On Tue, 23 Dec 2025 09:37:43 +0900, Christoph Hellwig wrote:
> commit 66fa3cedf16a ("fs: Add async write file modification handling.")
> effectively disabled IOCB_NOWAIT writes as timestamp updates currently
> always require blocking, and the modern timestamp resolution means we
> always update timestamps.  This leads to a lot of context switches from
> applications using io_uring to submit file writes, making it often worse
> than using the legacy aio code that is not using IOCB_NOWAIT.
> 
> [...]

Applied to the vfs-7.0.nonblocking_timestamps branch of the vfs/vfs.git tree.
Patches in the vfs-7.0.nonblocking_timestamps 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-7.0.nonblocking_timestamps

[01/11] fs: remove inode_update_time
        https://git.kernel.org/vfs/vfs/c/a3c5dc04be9f
[02/11] fs: allow error returns from generic_update_time
        https://git.kernel.org/vfs/vfs/c/829f055d68ee
[03/11] fs: exit early in generic_update_time when there is no work
        https://git.kernel.org/vfs/vfs/c/3c5f7a9696fa
[04/11] fs: delay the actual timestamp updates in inode_update_timestamps
        https://git.kernel.org/vfs/vfs/c/6e827e32c6ae
[05/11] fs: return I_DIRTY_* and allow error returns from inode_update_timestamps
        https://git.kernel.org/vfs/vfs/c/b79904581c69
[06/11] fs: factor out a sync_lazytime helper
        https://git.kernel.org/vfs/vfs/c/0cd53e2011e2
[07/11] fs: add a ->sync_lazytime method
        https://git.kernel.org/vfs/vfs/c/641284ff9133
[08/11] fs: add support for non-blocking timestamp updates
        https://git.kernel.org/vfs/vfs/c/3cb9ff38ddaf
[09/11] fat: enable non-blocking timestamp updates
        https://git.kernel.org/vfs/vfs/c/1736c77f0834
[10/11] xfs: implement ->sync_lazytime
        https://git.kernel.org/vfs/vfs/c/831c93b34fa4
[11/11] xfs: enable non-blocking timestamp updates
        https://git.kernel.org/vfs/vfs/c/bafbe984c54e