Add UNSHARING of filesystems and EXPORTING pools

As a 'stop' action ensure the filesystem is unshared before
it is unmounted, just in case.  Additionally, export the pool
so it may be cleanly imported by a different host.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2003

etc/init.d/zfs.lsb.in

@@ -106,10 +106,21 @@ stop()
 {
 	[ ! -f "$LOCKFILE" ] && return 3
 
+	log_begin_msg "Unsharing ZFS filesystems"
+	"$ZFS" unshare -a
+	log_end_msg $?
+
 	log_begin_msg "Unmounting ZFS filesystems"
 	"$ZFS" umount -a
 	log_end_msg $?
 
+	log_begin_msg "Exporting ZFS pools"
+	"$ZPOOL" list -H -o name | \
+	    while read pool; do
+		"$ZPOOL" export $pool
+	done
+	log_end_msg $?
+
 	rm -f "$LOCKFILE"
 }