On Mon, Aug 25, 2025 at 05:43:21AM +0100, Al Viro wrote:
> Both 'parent' and 'ns' are used at most once, no point precalculating those...
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
> fs/namespace.c | 12 ++++--------
> 1 file changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index a8b586e635d8..1a076aac5d73 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -3564,10 +3564,8 @@ static inline bool may_use_mount(struct mount *mnt)
> static int do_move_mount(struct path *old_path,
> struct path *new_path, enum mnt_tree_flags_t flags)
> {
> - struct mnt_namespace *ns;
> struct mount *p;
> struct mount *old;
> - struct mount *parent;
> struct pinned_mountpoint mp;
> int err;
> bool beneath = flags & MNT_TREE_BENEATH;
> @@ -3578,8 +3576,6 @@ static int do_move_mount(struct path *old_path,
>
> old = real_mount(old_path->mnt);
> p = real_mount(new_path->mnt);
> - parent = old->mnt_parent;
> - ns = old->mnt_ns;
>
> err = -EINVAL;
>
> @@ -3588,12 +3584,12 @@ static int do_move_mount(struct path *old_path,
> /* ... it should be detachable from parent */
> if (!mnt_has_parent(old) || IS_MNT_LOCKED(old))
> goto out;
> + /* ... which should not be shared */
> + if (IS_MNT_SHARED(old->mnt_parent))
> + goto out;
> /* ... and the target should be in our namespace */
> if (!check_mnt(p))
> goto out;
> - /* parent of the source should not be shared */
> - if (IS_MNT_SHARED(parent))
> - goto out;
> } else {
> /*
> * otherwise the source must be the root of some anon namespace.
> @@ -3605,7 +3601,7 @@ static int do_move_mount(struct path *old_path,
> * subsequent checks would've rejected that, but they lose
> * some corner cases if we check it early.
> */
> - if (ns == p->mnt_ns)
> + if (old->mnt_ns == p->mnt_ns)
> goto out;
> /*
> * Target should be either in our namespace or in an acceptable
> --
> 2.47.2
>
