linux-kernel - Re: [PATCH 02/14] fs: lift the FMODE_NOCMTIME check into file_update_time

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Message-ID: <5wv5u2sto54yelpzkxtdoekhfix7tsh5v7cyjrbnbvdvqmlssz@zpomezchur2d>
Date: Mon, 24 Nov 2025 12:54:33 +0100
From: Jan Kara <jack@...e.cz>
To: Christoph Hellwig <hch@....de>
Cc: Christian Brauner <brauner@...nel.org>, 
	Al Viro <viro@...iv.linux.org.uk>, David Sterba <dsterba@...e.com>, Jan Kara <jack@...e.cz>, 
	Mike Marshall <hubcap@...ibond.com>, Martin Brandenburg <martin@...ibond.com>, 
	Carlos Maiolino <cem@...nel.org>, Stefan Roesch <shr@...com>, Jeff Layton <jlayton@...nel.org>, 
	linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org, gfs2@...ts.linux.dev, 
	io-uring@...r.kernel.org, devel@...ts.orangefs.org, linux-unionfs@...r.kernel.org, 
	linux-mtd@...ts.infradead.org, linux-xfs@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [PATCH 02/14] fs: lift the FMODE_NOCMTIME check into
 file_update_time_flags

On Fri 14-11-25 07:26:05, Christoph Hellwig wrote:
> FMODE_NOCMTIME used to be just a hack for the legacy XFS handle-based
> "invisible I/O", but commit e5e9b24ab8fa ("nfsd: freeze c/mtime updates
> with outstanding WRITE_ATTRS delegation") started using it from
> generic callers.
> 
> I'm not sure other file systems are actually read for this in general,
						^^ ready

> so the above commit should get a closer look, but for it to make any
> sense, file_update_time needs to respect the flag.
> 
> Lift the check from file_modified_flags to file_update_time so that
> users of file_update_time inherit the behavior and so that all the
> checks are done in one place.
> 
> Fixes: e5e9b24ab8fa ("nfsd: freeze c/mtime updates with outstanding WRITE_ATTRS delegation")
> Signed-off-by: Christoph Hellwig <hch@....de>

Reagrdless whether FMODE_NOCMTIME works properly for all filesystems this
looks like a sensible step so feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/inode.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index 4884ffa931e7..24dab63844db 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -2320,6 +2320,8 @@ static int file_update_time_flags(struct file *file, unsigned int flags)
>  	/* First try to exhaust all avenues to not sync */
>  	if (IS_NOCMTIME(inode))
>  		return 0;
> +	if (unlikely(file->f_mode & FMODE_NOCMTIME))
> +		return 0;
>  
>  	now = current_time(inode);
>  
> @@ -2391,8 +2393,6 @@ static int file_modified_flags(struct file *file, int flags)
>  	ret = file_remove_privs_flags(file, flags);
>  	if (ret)
>  		return ret;
> -	if (unlikely(file->f_mode & FMODE_NOCMTIME))
> -		return 0;
>  	return file_update_time_flags(file, flags);
>  }
>  
> -- 
> 2.47.3
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR