code: Block[] getFileBlocks(String src) {
      waitForReady();
      byte[][] components = INodeDirectory.getPathComponents(src);
      readLock();
      try {
        INode targetNode = rootDir.getNode(components);
        if (targetNode == null)
          return null;
        if(targetNode.isDirectory())
          return null;
        return ((INodeFile)targetNode).getBlocks();
      } finally {
        readUnlock();
      }
    }
docs: Get the blocks associated with the file.