Starting with a completely clean environment:
root@ubuntu:/# ls -la /tank/docker-compressed/
total 3
drwxr-xr-x 2 root root 2 Dec 9 13:09 .
drwxr-xr-x 4 root root 4 Dec 8 15:56 ..
root@ubuntu:/# zfs list
NAME USED AVAIL REFER MOUNTPOINT
tank 22.5M 19.5G 32K /tank