}
      return remaining > 0 ? remaining : 0;
    }
      
<<<<<<< HEAD
    synchronized FSVolume getNextVolume(long blockSize) throws IOException {
      return blockChooser.chooseVolume(volumes, blockSize);
=======
    long getAvailable() throws IOException {
      long remaining = getCapacity()-getDfsUsed();
      long available = usage.getAvailable();
      if (remaining>available) {
        remaining = available;
      }
      return (remaining > 0) ? remaining : 0;
    }
      
    long getReserved(){
      return reserved;
    }
    
    String getMount() throws IOException {
      return usage.getMount();
    }
    
    BlockPoolSlice getBlockPoolSlice(String bpid) throws IOException {
      BlockPoolSlice bp = map.get(bpid);
      if (bp == null) {
        throw new IOException("block pool " + bpid + " is not found");
      }
      return bp;
    }
    
    /**
     * Make a deep copy of the list of currently active BPIDs
     */
    String[] getBlockPoolList() {
      synchronized(FSDataset.this) {
        return map.keySet().toArray(new String[map.keySet().size()]);   
      }
    }
      
    /**
     * Temporary files. They get moved to the finalized block directory when
     * the block is finalized.
     */
    File createTmpFile(String bpid, Block b) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.createTmpFile(b);
    }

    /**
     * RBW files. They get moved to the finalized block directory when
     * the block is finalized.
     */
    File createRbwFile(String bpid, Block b) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.createRbwFile(b);
    }

    File addBlock(String bpid, Block b, File f) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.addBlock(b, f);
    }
      
    void checkDirs() throws DiskErrorException {
      // TODO:FEDERATION valid synchronization
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().checkDirs();
    /**
        }
    }
      
    void getVolumeMap(ReplicasMap volumeMap) throws IOException {
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().getVolumeMap(volumeMap);
      }
    }
    
    void getVolumeMap(String bpid, ReplicasMap volumeMap) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      bp.getVolumeMap(volumeMap);
    }
    
     * Add replicas under the given directory to the volume map
     * @param volumeMap the replicas map
     * @param dir an input directory
     * @param isFinalized true if the directory has finalized replicas;
     *                    false if the directory has rbw replicas
     * @throws IOException 
     */
    private void addToReplicasMap(String bpid, ReplicasMap volumeMap, 
        File dir, boolean isFinalized) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      // TODO move this up
      // dfsUsage.incDfsUsed(b.getNumBytes()+metaFile.length());
      bp.addToReplicasMap(volumeMap, dir, isFinalized);
    }
    
    void clearPath(String bpid, File f) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      bp.clearPath(f);
    }
      
    public String toString() {
      return currentDir.getAbsolutePath();
    }

    public void shutdown() {
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().shutdown();
      }
    }

    public void addBlockPool(String bpid, Configuration conf)
        throws IOException {
      File bpdir = new File(currentDir, bpid);
      BlockPoolSlice bp = new BlockPoolSlice(bpid, this, bpdir, conf);
      map.put(bpid, bp);
    }
    
    public void shutdownBlockPool(String bpid) {
      BlockPoolSlice bp = map.get(bpid);
      if (bp!=null) {
        bp.shutdown();
      }
      map.remove(bpid);
    }

    private boolean isBPDirEmpty(String bpid)
        throws IOException {
      File volumeCurrentDir = this.getCurrentDir();
      File bpDir = new File(volumeCurrentDir, bpid);
      File bpCurrentDir = new File(bpDir, DataStorage.STORAGE_DIR_CURRENT);
      File finalizedDir = new File(bpCurrentDir,
          DataStorage.STORAGE_DIR_FINALIZED);
      File rbwDir = new File(bpCurrentDir, DataStorage.STORAGE_DIR_RBW);
      if (finalizedDir.exists() && finalizedDir.list().length != 0) {
        return false;
      }
      if (rbwDir.exists() && rbwDir.list().length != 0) {
        return false;
      }
      return true;
    }
    
    private void deleteBPDirectories(String bpid, boolean force)
        throws IOException {
      File volumeCurrentDir = this.getCurrentDir();
      File bpDir = new File(volumeCurrentDir, bpid);
      if (!bpDir.isDirectory()) {
        // nothing to be deleted
        return;
      }
      File tmpDir = new File(bpDir, DataStorage.STORAGE_DIR_TMP);
      File bpCurrentDir = new File(bpDir, DataStorage.STORAGE_DIR_CURRENT);
      File finalizedDir = new File(bpCurrentDir,
          DataStorage.STORAGE_DIR_FINALIZED);
      File rbwDir = new File(bpCurrentDir, DataStorage.STORAGE_DIR_RBW);
      if (force) {
        FileUtil.fullyDelete(bpDir);
      } else {
        if (!rbwDir.delete()) {
          throw new IOException("Failed to delete " + rbwDir);
        }
        if (!finalizedDir.delete()) {
          throw new IOException("Failed to delete " + finalizedDir);
        }
        FileUtil.fullyDelete(tmpDir);
        for (File f : bpCurrentDir.listFiles()) {
          if (!f.delete()) {
            throw new IOException("Failed to delete " + f);
          }
        }
        if (!bpCurrentDir.delete()) {
          throw new IOException("Failed to delete " + bpCurrentDir);
        }
        for (File f : bpDir.listFiles()) {
          if (!f.delete()) {
            throw new IOException("Failed to delete " + f);
          }
        if (!bpDir.delete()) {
          throw new IOException("Failed to delete " + bpDir);
        }
      }
>>>>>>> f529dfe74535d09556f82a0d9da0e1137410e8a0
    }
  }
    

      return remaining > 0 ? remaining : 0;
    }
      
    long getAvailable() throws IOException {
      long remaining = getCapacity()-getDfsUsed();
      long available = usage.getAvailable();
      if (remaining>available) {
        remaining = available;
      }
      return (remaining > 0) ? remaining : 0;
    }
      
    long getReserved(){
      return reserved;
    }
    
    String getMount() throws IOException {
      return usage.getMount();
    }
    
    BlockPoolSlice getBlockPoolSlice(String bpid) throws IOException {
      BlockPoolSlice bp = map.get(bpid);
      if (bp == null) {
        throw new IOException("block pool " + bpid + " is not found");
      }
      return bp;
    }
    
    /**
     * Make a deep copy of the list of currently active BPIDs
     */
    String[] getBlockPoolList() {
      synchronized(FSDataset.this) {
        return map.keySet().toArray(new String[map.keySet().size()]);   
      }
    }
      
    /**
     * Temporary files. They get moved to the finalized block directory when
     * the block is finalized.
     */
    File createTmpFile(String bpid, Block b) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.createTmpFile(b);
    }

    /**
     * RBW files. They get moved to the finalized block directory when
     * the block is finalized.
     */
    File createRbwFile(String bpid, Block b) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.createRbwFile(b);
    }

    File addBlock(String bpid, Block b, File f) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      return bp.addBlock(b, f);
    }
      
    void checkDirs() throws DiskErrorException {
      // TODO:FEDERATION valid synchronization
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().checkDirs();
      }
    }
      
    void getVolumeMap(ReplicasMap volumeMap) throws IOException {
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().getVolumeMap(volumeMap);
      }
    }
    
    void getVolumeMap(String bpid, ReplicasMap volumeMap) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      bp.getVolumeMap(volumeMap);
    }
    
    /**
     * Add replicas under the given directory to the volume map
     * @param volumeMap the replicas map
     * @param dir an input directory
     * @param isFinalized true if the directory has finalized replicas;
     *                    false if the directory has rbw replicas
     * @throws IOException 
     */
    private void addToReplicasMap(String bpid, ReplicasMap volumeMap, 
        File dir, boolean isFinalized) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      // TODO move this up
      // dfsUsage.incDfsUsed(b.getNumBytes()+metaFile.length());
      bp.addToReplicasMap(volumeMap, dir, isFinalized);
    }
    
    void clearPath(String bpid, File f) throws IOException {
      BlockPoolSlice bp = getBlockPoolSlice(bpid);
      bp.clearPath(f);
    }
      
    public String toString() {
      return currentDir.getAbsolutePath();
    }

    public void shutdown() {
      Set> set = map.entrySet();
      for (Entry entry : set) {
        entry.getValue().shutdown();
      }
    }

    public void addBlockPool(String bpid, Configuration conf)
        throws IOException {
      File bpdir = new File(currentDir, bpid);
      BlockPoolSlice bp = new BlockPoolSlice(bpid, this, bpdir, conf);
      map.put(bpid, bp);
    }
    
    public void shutdownBlockPool(String bpid) {
      BlockPoolSlice bp = map.get(bpid);
      if (bp!=null) {
        bp.shutdown();
      }
      map.remove(bpid);
    }

    private boolean isBPDirEmpty(String bpid)
        throws IOException {
      File volumeCurrentDir = this.getCurrentDir();
      File bpDir = new File(volumeCurrentDir, bpid);
      File bpCurrentDir = new File(bpDir, DataStorage.STORAGE_DIR_CURRENT);
      File finalizedDir = new File(bpCurrentDir,
          DataStorage.STORAGE_DIR_FINALIZED);
      File rbwDir = new File(bpCurrentDir, DataStorage.STORAGE_DIR_RBW);
      if (finalizedDir.exists() && finalizedDir.list().length != 0) {
        return false;
      }
      if (rbwDir.exists() && rbwDir.list().length != 0) {
        return false;
      }
      return true;
    }
    
    private void deleteBPDirectories(String bpid, boolean force)
        throws IOException {
      File volumeCurrentDir = this.getCurrentDir();
      File bpDir = new File(volumeCurrentDir, bpid);
      if (!bpDir.isDirectory()) {
        // nothing to be deleted
        return;
      }
      File tmpDir = new File(bpDir, DataStorage.STORAGE_DIR_TMP);
      File bpCurrentDir = new File(bpDir, DataStorage.STORAGE_DIR_CURRENT);
      File finalizedDir = new File(bpCurrentDir,
          DataStorage.STORAGE_DIR_FINALIZED);
      File rbwDir = new File(bpCurrentDir, DataStorage.STORAGE_DIR_RBW);
      if (force) {
        FileUtil.fullyDelete(bpDir);
      } else {
        if (!rbwDir.delete()) {
          throw new IOException("Failed to delete " + rbwDir);
        }
        if (!finalizedDir.delete()) {
          throw new IOException("Failed to delete " + finalizedDir);
        }
        FileUtil.fullyDelete(tmpDir);
        for (File f : bpCurrentDir.listFiles()) {
          if (!f.delete()) {
            throw new IOException("Failed to delete " + f);
          }
        }
        if (!bpCurrentDir.delete()) {
          throw new IOException("Failed to delete " + bpCurrentDir);
        }
        for (File f : bpDir.listFiles()) {
          if (!f.delete()) {
            throw new IOException("Failed to delete " + f);
          }
        }
        if (!bpDir.delete()) {
          throw new IOException("Failed to delete " + bpDir);
        }
      }
    }
  }