ceph: don't open-code the check for dead lockref

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ceph/dir.c

@@ -1255,7 +1255,7 @@ __dentry_leases_walk(struct ceph_mds_client *mdsc,
 		if (!spin_trylock(&dentry->d_lock))
 			continue;
 
-		if (dentry->d_lockref.count < 0) {
+		if (__lockref_is_dead(&dentry->d_lockref)) {
 			list_del_init(&di->lease_list);
 			goto next;
 		}