LockD: manage used host count per networks namespace

This patch introduces moves nrhosts in per-net data.
It also adds kernel warning to nlm_shutdown_hosts_net() about remaining hosts
in specified network namespace context.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/lockd/netns.h b/fs/lockd/netns.h
index 97c6c77..44c8f0b 100644
--- a/fs/lockd/netns.h
+++ b/fs/lockd/netns.h
@@ -6,6 +6,7 @@
 struct lockd_net {
 	unsigned int nlmsvc_users;
 	unsigned long next_gc;
+	unsigned long nrhosts;
 };
 
 extern int lockd_net_id;