private int getNumNonNull(INodesInPath iip) {
   List<INode> inodes = iip.getReadOnlyINodes();
   for (int i = inodes.size() - 1; i >= 0; i--) {
     if (inodes.get(i) != null) {
       return i + 1;
     }
   }
   return 0;
 }