code: private boolean discardDone(INodeFileUnderConstruction pendingFile,
                                String src) throws IOException {
      Block[] blocks = pendingFile.getBlocks();
      if (blocks == null || blocks.length == 0) {
        return false;
      }
      Block last = blocks[blocks.length-1];
      if (last.getNumBytes() == 0) {
        dir.removeBlock(src, pendingFile, last);
        finalizeINodeFileUnderConstruction(src, pendingFile);
        NameNode.stateChangeLog.warn("BLOCK*" +
            " internalReleaseLease: discarded last block " + last +
            " , lease removed for " +  src);
        return true;
      }
      return false;
    }
docs: the last block completely.