cheat.sheets: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

 tldr:btrfs 
# Create subvolume:
sudo btrfs subvolume create path/to/subvolume

# List subvolumes:
sudo btrfs subvolume list path/to/mount_point

# Enable quota:
sudo btrfs quota enable path/to/subvolume

# Show quota:
sudo btrfs qgroup show path/to/subvolume