code: void deleteAsyncFile(FSDataset.FSVolume volume, File file){
  	    DataNode.LOG.info("Scheduling file " + file.toString() + " for deletion");
  	    FileDeleteTask deletionTask =
  	        new FileDeleteTask(volume, file);
  	    execute(volume.getCurrentDir(), deletionTask);
  	  }
docs: Delete a file or directory from the disk asynchronously.
  Used for deleting obsolete block files.
  Does not change dfs usage stats.