lockd: get rid of reference-counted NSM RPC clients

Currently we have reference-counted per-net NSM RPC client
which created on the first monitor request and destroyed
after the last unmonitor request. It's needed because
RPC client need to know 'utsname()->nodename', but utsname()
might be NULL when nsm_unmonitor() called.

So instead of holding the rpc client we could just save nodename
in struct nlm_host and pass it to the rpc_create().
Thus ther is no need in keeping rpc client until last
unmonitor request. We could create separate RPC clients
for each monitor/unmonitor requests.

Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/lockd/netns.h

@@ -12,9 +12,6 @@ struct lockd_net {
 	struct delayed_work grace_period_end;
 	struct lock_manager lockd_manager;
 
-	spinlock_t nsm_clnt_lock;
-	unsigned int nsm_users;
-	struct rpc_clnt *nsm_clnt;
 	struct list_head nsm_handles;
 };