linux-kernel - Re: [PATCH v2] dcache: touch up predicts in __d_lookup

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Message-ID: <20251128-hinblick-heimfahren-c73d29b4c5ab@brauner>
Date: Fri, 28 Nov 2025 10:32:09 +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 v2] dcache: touch up predicts in __d_lookup_rcu()

On Thu, 27 Nov 2025 14:15:26 +0100, Mateusz Guzik wrote:
> Rationale is that if the parent dentry is the same and the length is the
> same, then you have to be unlucky for the name to not match.
> 
> At the same time the dentry was literally just found on the hash, so you
> have to be even more unlucky to determine it is unhashed.
> 
> While here add commentary while d_unhashed() is necessary. It was
> already removed once and brought back in:
> 2e321806b681b192 ("Revert "vfs: remove unnecessary d_unhashed() check from __d_lookup_rcu"")
> 
> [...]

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

[1/1] dcache: touch up predicts in __d_lookup_rcu()
      https://git.kernel.org/vfs/vfs/c/ca0d620b0afa