public FileStatus[] getWALDirPaths(final PathFilter filter) throws IOException {
    Path walDirPath = new Path(CommonFSUtils.getWALRootDir(conf), HConstants.HREGION_LOGDIR_NAME);
    FileStatus[] walDirForServerNames = CommonFSUtils.listStatus(fs, walDirPath, filter);
    return walDirForServerNames == null ? new FileStatus[0] : walDirForServerNames;
  }
Returns List of all RegionServer WAL dirs; i.e. this.rootDir/HConstants.HREGION_LOGDIR_NAME.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterWalManager.java