linux-kernel - Re: [PATCH] vfs: elide smp_mb in iversion handling in the common case

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Message-ID: <20240816-wertarbeit-steil-90ff676fb2d1@brauner>
Date: Fri, 16 Aug 2024 12:56:19 +0200
From: Christian Brauner <brauner@...nel.org>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: Christian Brauner <brauner@...nel.org>,
	viro@...iv.linux.org.uk,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] vfs: elide smp_mb in iversion handling in the common case

On Thu, 15 Aug 2024 10:33:10 +0200, Mateusz Guzik wrote:
> According to bpftrace on these routines most calls result in cmpxchg,
> which already provides the same guarantee.
> 
> In inode_maybe_inc_iversion elision is possible because even if the
> wrong value was read due to now missing smp_mb fence, the issue is going
> to correct itself after cmpxchg. If it appears cmpxchg wont be issued,
> the fence + reload are there bringing back previous behavior.
> 
> [...]

Applied to the vfs.misc branch of the vfs/vfs.git tree.
Patches in the vfs.misc 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.misc

[1/1] vfs: elide smp_mb in iversion handling in the common case
      https://git.kernel.org/vfs/vfs/c/5570f04d0bb1