# btrfs subvolume list /
ID 257 gen 34 top level 5 path @
ID 258 gen 257743 top level 257 path @/var
ID 259 gen 257498 top level 257 path @/usr/local
ID 260 gen 257743 top level 257 path @/tmp
ID 261 gen 186732 top level 257 path @/srv
ID 262 gen 257736 top level 257 path @/root
ID 263 gen 257616 top level 257 path @/opt
ID 264 gen 257286 top level 257 path @/home
ID 265 gen 28 top level 257 path @/boot/grub2/x86_64-efi
ID 266 gen 224143 top level 257 path @/boot/grub2/i386-pc
ID 267 gen 257708 top level 257 path @/.snapshots
ID 268 gen 257743 top level 267 path @/.snapshots/1/snapshot
ID 400 gen 62349 top level 258 path @/var/lib/machines
ID 568 gen 253867 top level 267 path @/.snapshots/191/snapshot
...
# mount | grep /home
/dev/sda1 on /home type btrfs
(rw,relatime,ssd,space_cache,subvolid=264,subvol=/@/home)
# btrfs subvolume delete @/home
ERROR: cannot access subvolume @/home: No such file or directory
# umount /home
# mount | grep /home
# btrfs subvolume delete @/home
ERROR: cannot access subvolume @/home: No such file or directory