linux-kernel - Re: [PATCH v2 1/2] filelock: use a consume fence in locks_inode

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Message-ID: <1d73231c675b6d77ca42d8f7a0a866c82c3be821.camel@kernel.org>
Date: Wed, 12 Nov 2025 06:49:21 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Mateusz Guzik <mjguzik@...il.com>, brauner@...nel.org
Cc: viro@...iv.linux.org.uk, jack@...e.cz, linux-kernel@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] filelock: use a consume fence in
 locks_inode_context()

On Wed, 2025-11-12 at 11:44 +0100, Mateusz Guzik wrote:
> Matches the idiom of storing a pointer with a release fence and safely
> getting the content with a consume fence after.
> 
> Eliminates an actual fence on some archs.
> 
> Signed-off-by: Mateusz Guzik <mjguzik@...il.com>
> ---
>  include/linux/filelock.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/filelock.h b/include/linux/filelock.h
> index c2ce8ba05d06..37e1b33bd267 100644
> --- a/include/linux/filelock.h
> +++ b/include/linux/filelock.h
> @@ -232,7 +232,10 @@ bool locks_owner_has_blockers(struct file_lock_context *flctx,
>  static inline struct file_lock_context *
>  locks_inode_context(const struct inode *inode)
>  {
> -	return smp_load_acquire(&inode->i_flctx);
> +	/*
> +	 * Paired with the fence in locks_get_lock_context().
> +	 */
> +	return READ_ONCE(inode->i_flctx);
>  }
>  
>  #else /* !CONFIG_FILE_LOCKING */

Seems reasonable

Reviewed-by: Jeff Layton <jlayton@...nel.org>