long getCapacity() throws IOException {
      if (reserved > usage.getCapacity()) {
        return 0;
      }

      return usage.getCapacity() - reserved;
    }
 long getAvailable() throws IOException {
   long remaining = getCapacity() - getDfsUsed();
   long available = usage.getAvailable();
   if (remaining > available) {
     remaining = available;
   }
   return (remaining > 0) ? remaining : 0;
 }
 String getMount() throws IOException {
   return usage.getMount();
 }