bigsur-unmount-fail.sh

#!/bin/bash -x
sw_vers
zpool version

NUMSECTORS=1280000 
mydev=`hdiutil attach -nomount ram://$NUMSECTORS`
sudo zpool create foo $mydev
sudo zfs snapshot foo@s1
sudo zfs create foo/bar
sudo zfs rollback foo@s1
sudo zfs unmount foo/bar
sudo zfs unmount -f foo/bar
sudo zfs unmount foo
sudo zfs unmount -f foo
sudo umount -f /Volumes/foo/bar
sudo umount -f /Volumes/foo
sudo zfs mount -a
sudo zpool export foo