Re: [RFC][PATCH 02/13] do_fchmodat(): import pathname only once

Jan Kara
2025-11-13T10:12:20Z

On Sun 09-11-25 06:37:34, Al Viro wrote:
> Convert the user_path_at() call inside a retry loop into getname_flags() +
> filename_lookup() + putname() and leave only filename_lookup() inside
> the loop.
>
> Since we have the default logics for use of LOOKUP_EMPTY (passed iff
> AT_EMPTY_PATH is present in flags), just use getname_uflags() and
> don't bother with setting LOOKUP_EMPTY in lookup_flags - getname_uflags()
> will pass the right thing to getname_flags() and filename_lookup()
> doesn't care about LOOKUP_EMPTY at all.
>
> The things could be further simplified by use of cleanup.h stuff, but
> let's not clutter the patch with that.
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Looks good. Feel free to add:

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

Honza

> ---
> fs/open.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/open.c b/fs/open.c
> index db8fe2b5463d..e9a08a820e49 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -682,6 +682,7 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
> unsigned int flags)
> {
> struct path path;
> + struct filename *name;
> int error;
> unsigned int lookup_flags;
>
> @@ -689,11 +690,9 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
> return -EINVAL;
>
> lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
> - if (flags & AT_EMPTY_PATH)
> - lookup_flags |= LOOKUP_EMPTY;
> -
> + name = getname_uflags(filename, flags);
> retry:
> - error = user_path_at(dfd, filename, lookup_flags, &path);
> + error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
> if (!error) {
> error = chmod_common(&path, mode);
> path_put(&path);
> @@ -702,6 +701,7 @@ static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
> goto retry;
> }
> }
> + putname(name);
> return error;
> }
>
> --
> 2.47.3
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR