Path file = fileSplit.getPath();
FileSystem fs = file.getFileSystem(conf);
in = fs.open(file, 16 * 1024 * 1024);
in.seek(fileSplit.getStart());
if (MongoConfigUtil.getLazyBSON(conf)) {
callback = new LazyBSONCallback();
decoder = new LazyBSONDecoder();
} else {
callback = new BasicBSONCallback();
decoder = new BasicBSONDecoder();
}