Re: [PATCH 1/9] allow finish_no_open(file, ERR_PTR(-E...))

[NeilBrown <neilb@ownmail.net>]

On Sat, 13 Sep 2025, Al Viro wrote:
> ... allowing any ->lookup() return value to be passed to it.
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  fs/open.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/open.c b/fs/open.c
> index 9655158c3885..4890b13461c7 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -1059,18 +1059,20 @@ EXPORT_SYMBOL(finish_open);
>   * finish_no_open - finish ->atomic_open() without opening the file
>   *
>   * @file: file pointer
> - * @dentry: dentry or NULL (as returned from ->lookup())
> + * @dentry: dentry, ERR_PTR(-E...) or NULL (as returned from ->lookup())
>   *
> - * This can be used to set the result of a successful lookup in ->atomic_open().
> + * This can be used to set the result of a lookup in ->atomic_open().

This is my favourite part of the series - removing the word
"successful".  It makes the API more general.

My only other thought is that

	if (d_in_lookup(dentry)) {
		struct dentry *res = dir->i_op->lookup(dir, dentry, 0);
		if (res || d_really_is_positive(dentry))
			return finish_no_open(file, res);
	}

is a common pattern.  It would be nice if we could factor it out into a
help but I cannot think of a clean way to do that.
You can add
Reviewed-by: NeilBrown <neil@brown.name>
if you like.

Thanks,
NeilBrown

>   *
>   * NB: unlike finish_open() this function does consume the dentry reference and
>   * the caller need not dput() it.
>   *
> - * Returns "0" which must be the return value of ->atomic_open() after having
> - * called this function.
> + * Returns 0 or -E..., which must be the return value of ->atomic_open() after
> + * having called this function.
>   */
>  int finish_no_open(struct file *file, struct dentry *dentry)
>  {
> +	if (IS_ERR(dentry))
> +		return PTR_ERR(dentry);
>  	file->f_path.dentry = dentry;
>  	return 0;
>  }
> -- 
> 2.47.2
> 
>