def get_volume_id_to_instance_id_map(volume_info):
    """Generate volume id to instance id map.  Unattached volumes will be ignored."""
    instance_id_to_volume_id_map = {}
    for volume_id in volume_info:
        volume = volume_info.get(volume_id)
        if volume.get('Attachments'):
            ec2_instance_id = volume.get('Attachments')[0].get('InstanceId')
            instance_id_to_volume_id_map[volume_id] = ec2_instance_id
    return instance_id_to_volume_id_map
