linux-kernel - Re: [PATCH] fs: move inode fields used during fast path lookup closer together

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Message-ID: <20251111-zeremonie-amortisieren-d1455ae20d5f@brauner>
Date: Tue, 11 Nov 2025 10:50:07 +0100
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] fs: move inode fields used during fast path lookup closer together

On Sun, 09 Nov 2025 13:19:31 +0100, Mateusz Guzik wrote:
> This should avoid *some* cache misses.
> 
> Successful path lookup is guaranteed to load at least ->i_mode,
> ->i_opflags and ->i_acl. At the same time the common case will avoid
> looking at more fields.
> 
> struct inode is not guaranteed to have any particular alignment, notably
> ext4 has it only aligned to 8 bytes meaning nearby fields might happen
> to be on the same or only adjacent cache lines depending on luck (or no
> luck).
> 
> [...]

Applied to the vfs-6.19.fs_header branch of the vfs/vfs.git tree.
Patches in the vfs-6.19.fs_header 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.fs_header

[1/1] fs: move inode fields used during fast path lookup closer together
      https://git.kernel.org/vfs/vfs/c/dca3aa666fbd