zfs snapdir: from hidden to visible and back again

[Andriy Gapon]

I needed to check some files in earlier snapshot, so I did:
$ zfs set snapdir=visible tank/usr/local
everything went well, I examined /usr/local/.zfs/.... and then did:
$ zfs set snapdir=hidden tank/usr/local
after that .zfs directory disappeared from output of ls -l /usr/local, BUT:
$ mount
...
tank/usr/local at upgradeall on /usr/local/.zfs/snapshot/upgradeall (zfs,
local, noatime, read-only)

This is the snapshot that I examined earlier.
Hmm, strange.

Then I did:
$ umount /usr/local/.zfs/snapshot/upgradeall

After that .zfs is not listed in /usr/local and mount command does not
list the snapshot anymore.
Is this correct behavior, did I have to do umount?

Also, even with snapdir=hidden, I still can list snapshots (their
contents) if I ls full path with .zfs in it.
Is this right?

-- 
Andriy Gapon