Re: [RFC][PATCH 08/13] do_sys_truncate(): import pathname only once

Jan Kara
2025-11-13T10:19:01Z

On Sun 09-11-25 06:37:40, 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.
>
> In this case we never pass LOOKUP_EMPTY, so getname_flags() is equivalent
> to plain getname().
>
> 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 | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/open.c b/fs/open.c
> index e67baae339fc..eb2ff940393d 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -129,14 +129,16 @@ EXPORT_SYMBOL_GPL(vfs_truncate);
> int do_sys_truncate(const char __user *pathname, loff_t length)
> {
> unsigned int lookup_flags = LOOKUP_FOLLOW;
> + struct filename *name;
> struct path path;
> int error;
>
> if (length < 0) /* sorry, but loff_t says... */
> return -EINVAL;
>
> + name = getname(pathname);
> retry:
> - error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
> + error = filename_lookup(AT_FDCWD, name, lookup_flags, &path, NULL);
> if (!error) {
> error = vfs_truncate(&path, length);
> path_put(&path);
> @@ -145,6 +147,7 @@ int do_sys_truncate(const char __user *pathname, loff_t length)
> lookup_flags |= LOOKUP_REVAL;
> goto retry;
> }
> + putname(name);
> return error;
> }
>
> --
> 2.47.3
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR