protected void read(DataInputStream inputStream) throws Exception {
            nextBlock = BlockPointer.pos(inputStream.readLong());
            largestInNextBlock = inputStream.readInt();
            int count = inputStream.readInt();
            for (int i = 0; i < count; i++) {
                BlockPointer pos = BlockPointer.pos(inputStream.readLong());
                int size = inputStream.readInt();