code: protected DistributedFileSystem getDFS(Path p) throws IOException {
      FileSystem fs = p.getFileSystem(getConf());
      DistributedFileSystem dfs = null;
      if (fs instanceof DistributedFileSystem) {
        dfs = (DistributedFileSystem) fs;
      } else if (fs instanceof FilterFileSystem) {
        FilterFileSystem ffs = (FilterFileSystem) fs;
        if (ffs.getRawFileSystem() instanceof DistributedFileSystem) {
          dfs = (DistributedFileSystem) ffs.getRawFileSystem();
        }
      }
      return dfs;
    }
docs: Returns a DistributedFileSystem hosting the path supplied.