linux-kernel - Re: [PATCH v3] fs: make sure to fail try_to_unlazy() and try_to_unlazy() for LOOKUP

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Message-ID: <20251224-zunichte-hautnah-57728a08cb13@brauner>
Date: Wed, 24 Dec 2025 13:32:10 +0100
From: Christian Brauner <brauner@...nel.org>
To: Mateusz Guzik <mjguzik@...il.com>
Cc: Christian Brauner <brauner@...nel.org>,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	clm@...a.com,
	viro@...iv.linux.org.uk
Subject: Re: [PATCH v3] fs: make sure to fail try_to_unlazy() and try_to_unlazy() for LOOKUP_CACHED

On Sat, 20 Dec 2025 06:40:22 +0100, Mateusz Guzik wrote:
> Otherwise the slowpath can be taken by the caller, defeating the flag.
> 
> This regressed after calls to legitimize_links() started being
> conditionally elided and stems from the routine always failing
> after seeing the flag, regardless if there were any links.
> 
> In order to address both the bug and the weird semantics make it illegal
> to call legitimize_links() with LOOKUP_CACHED and handle the problem at
> the two callsites.
> 
> [...]

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

[1/1] fs: make sure to fail try_to_unlazy() and try_to_unlazy() for LOOKUP_CACHED
      https://git.kernel.org/vfs/vfs/c/46af9ae1305f