@Override
  public void setConf(Configuration conf) {
    super.setConf(conf);

    // setup filesystem
    lock.writeLock().lock();
    try {
      this.fs = FileSystem.get(this.getConf());
    } catch (IOException e) {
      if (LOG.isDebugEnabled()) {
        LOG.debug("Couldn't instantiate the file system, not deleting file, just in case. "
          + FileSystem.FS_DEFAULT_NAME_KEY + "="
          + getConf().get(FileSystem.FS_DEFAULT_NAME_KEY, FileSystem.DEFAULT_FS));
      }
    } finally {
      lock.writeLock().unlock();
    }
  }
HFileLink cleaner that determines if a hfile should be deleted. HFiles can be deleted only if
there're no links to them. When a HFileLink is created a back reference file is created in:
/hbase/archive/table/region/cf/.links-hfile/ref-region.ref-table To check if the hfile can be
deleted the back references folder must be empty.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/HFileLinkCleaner.java