protected void modifyUsedDirsCount(int group, int diff) throws IOException  {
protected void modifyUsedDirsCount(int group, int diff) {
	protected void modifyUsedDirsCount(int group, int diff) throws IOException  {		GroupDescriptor gdesc = groupDescriptors[group];		synchronized(gdesc) {			gdesc.setUsedDirsCount( gdesc.getUsedDirsCount()+diff );		}	}