kernfs_get_active
if (!kernfs_get_active(parent))
if (!kernfs_get_active(kn))
if (!kernfs_get_active(kn))
if (!kernfs_get_active(new_parent)) {
if (!kernfs_get_active(kn))
if (!kernfs_get_active(of->kn))
struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);