NFS: make cb_ident_idr per net ns

This patch makes ID's infrastructure network namespace aware. This was done
mainly because of nfs_client_lock, which is desired to be per network
namespace, but protects NFS clients ID's.

NOTE: NFS client's net pointer have to be set prior to ID initialization,
proper assignment was moved.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/netns.h

@@ -9,6 +9,9 @@ struct nfs_net {
 	struct rpc_pipe *bl_device_pipe;
 	struct list_head nfs_client_list;
 	struct list_head nfs_volume_list;
+#ifdef CONFIG_NFS_V4
+	struct idr cb_ident_idr; /* Protected by nfs_client_lock */
+#endif
 };
 
 extern int nfs_net_id;