RW and RO semantic and unable to umount a partition?

[Steve Kargl]

So, I may have done something in the category of "Don't do that!".

On node n19, I export /dev/ad4s1e and combine it into a mirror
on node n18 with n18's /dev/ad4s1e.  On n18 I have /dev/mirror/data,
and I've successfully mounted /dev/mirror/data:

n18:root[32] mount /dev/mirror/data /data

Now, I tried the the following:

On n18, I created /etc/gg.exports

n18:root[33] cat /etc/gg.exports
192.168.0.17 RW /dev/mirror/data
n18:root[34] ggated -v

On node n17 (yes, a third system).  I do

n17:root[08] ggatec create -o rw 192.168.0.18 /dev/mirror/data

The above command does not create /dev/ggate0.  So, I tried 

ggatec create -o ro 192.168.0.18 /dev/mirror/data

This created the /dev/ggate0 device.  Now, the interesting
part

n17:root[10] mount /dev/ggate0 /mnt
n17:root[11] ls /mnt
.snap/  fcurra/ kargl/
n17:root[12] umount /mnt
umount: unmount of /mnt failed: Operation not permitted
n17:root[13] umount -f /mnt
umount: unmount of /mnt failed: Operation not permitted

Three questions.  Why is RW not permitted?  Why does umount
fail?  How the heck to I force umount or the unmounting of /mnt?


-- 
Steve