void clearPath(File f) {
   dataDir.clearPath(f);
 }
 void getVolumeMap(HashMap<Block, DatanodeBlockInfo> volumeMap) {
   dataDir.getVolumeMap(volumeMap, this);
 }
 void checkDirs() throws DiskErrorException {
   dataDir.checkDirTree();
   DiskChecker.checkDir(tmpDir);
 }
 void getBlockInfo(TreeSet<Block> blockSet) {
   dataDir.getBlockInfo(blockSet);
 }
 File addBlock(Block b, File f) throws IOException {
   File blockFile = dataDir.addBlock(b, f);
   File metaFile = getMetaFile(blockFile, b);
   dfsUsage.incDfsUsed(b.getNumBytes() + metaFile.length());
   return blockFile;
 }