Re: [RFC][PATCH 01/13] do_faccessat(): import pathname only once

Jan Kara
2025-11-13T10:11:10Z

On Sun 09-11-25 06:37:33, 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 | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/open.c b/fs/open.c
> index 3d64372ecc67..db8fe2b5463d 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -471,6 +471,7 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
> int res;
> unsigned int lookup_flags = LOOKUP_FOLLOW;
> const struct cred *old_cred = NULL;
> + struct filename *name;
>
> if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
> return -EINVAL;
> @@ -480,8 +481,6 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
>
> if (flags & AT_SYMLINK_NOFOLLOW)
> lookup_flags &= ~LOOKUP_FOLLOW;
> - if (flags & AT_EMPTY_PATH)
> - lookup_flags |= LOOKUP_EMPTY;
>
> if (access_need_override_creds(flags)) {
> old_cred = access_override_creds();
> @@ -489,8 +488,9 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
> return -ENOMEM;
> }
>
> + name = getname_uflags(filename, flags);
> retry:
> - res = user_path_at(dfd, filename, lookup_flags, &path);
> + res = filename_lookup(dfd, name, lookup_flags, &path, NULL);
> if (res)
> goto out;
>
> @@ -530,6 +530,7 @@ static int do_faccessat(int dfd, const char __user *filename, int mode, int flag
> goto retry;
> }
> out:
> + putname(name);
> if (old_cred)
> put_cred(revert_creds(old_cred));
>
> --
> 2.47.3
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR