sudo btrfs quota enable /home
sudo btrfs qgroup show /home
qgroupid rfer excl -------- ---- ---- 0/5 142.21GiB 89.70MiB 0/410 96.00KiB 96.00KiB 0/2191 17.62GiB 0.00B 0/3237 137.90GiB 4.05GiB
qgroupid is the snapshot ID,
rfer is the total size of that snapshot (the size of the parent subvolumes are included),
excl is the exclusive space that particular snapshot occupies.
sudo btrfs subvolume list /home
Note that this will display the link between the
snapper -c home delete $SNAPPER_ID
You shouldn't delete the snapshot using
btrfs subvolume delete, as this will confuse Snapper.
If your filesystem has just suffered an episode of catastrophic failure, you might need to re-initialise things. A Snapper rollback can cause it.
for i in $(btrfs qgroup show /home | tail -n+3 | cut -d ' ' -f 1); do btrfs qgroup destroy $i /home; done btrfs quota disable /home btrfs quota enable /home