btrfs 
# create the subvolume /mnt/sv1 in the /mnt volume
btrfs subvolume create /mnt/sv1

# list subvolumes
btrfs subvolume list /mnt

# mount subvolume without mounting the main filesystem
mount -o subvol=sv1 /dev/sdb /mnt

# delete subvolume
btrfs subvolume delete /mnt/sv1

# taking snapshot of a subvolume
btrfs subvolume snapshot /mnt/sv1 /mnt/sv1_snapshot