code: static private int getPathDepth(INode inode) throws IOException {
      // calculate the depth of this inode from root
      int depth = 1;
      INode node; // node on the path to the root
      for (node = inode; node.parent != null; node = node.parent) {
        depth++;
      }
  
      // parent should be root
      if (node.isRoot()) {
        return depth;
      }
      
      // invalid inode
      throw new IOException("Invalid inode: " + inode.getLocalName());
    }
docs: Get the depth of node inode from root
  @param inode an inode
  @return depth
  @throws IOException if the given inode is invalid