class FSNamesystem implements Namesystem, FSNamesystemMBean,
  NameNodeMXBean {

  public int getEffectiveLayoutVersion() {
    return getEffectiveLayoutVersion(isRollingUpgrade(),
        fsImage.getStorage().getLayoutVersion(),
        NameNodeLayoutVersion.MINIMUM_COMPATIBLE_LAYOUT_VERSION,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
  }

    FSNamesystem(Configuration conf, FSImage fsImage);
    FSNamesystem(Configuration conf, FSImage fsImage, boolean ignoreRetryCache);

}