Parse the blkio metrics.

def _parse_blkio_metrics(self, stats):
        """Parse the blkio metrics."""
        metrics = {
            'io_read': 0,
            'io_write': 0,
        }
        for line in stats:
            if 'Read' in line:
                metrics['io_read'] += int(line.split()[2])
            if 'Write' in line:
                metrics['io_write'] += int(line.split()[2])
        return metrics