nfsd: make client_lock per net

This lock protects the client lru list and session hash table, which are
allocated per network namespace already.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 227b93e..08d5fa1 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -81,6 +81,9 @@
 	struct list_head close_lru;
 
 	struct delayed_work laundromat_work;
+
+	/* client_lock protects the client lru list and session hash table */
+	spinlock_t client_lock;
 };
 
 extern int nfsd_net_id;