NFSv4: Reduce the chances of an open_owner identifier collision

Currently we just use a 32-bit counter.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 6b42440..ccb4550 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -130,7 +130,6 @@
 #ifdef CONFIG_NFS_V4
 	init_rwsem(&clp->cl_sem);
 	INIT_LIST_HEAD(&clp->cl_delegations);
-	INIT_LIST_HEAD(&clp->cl_state_owners);
 	spin_lock_init(&clp->cl_lock);
 	INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
 	rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
@@ -154,7 +153,7 @@
 #ifdef CONFIG_NFS_V4
 	if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
 		nfs4_kill_renewd(clp);
-	BUG_ON(!list_empty(&clp->cl_state_owners));
+	BUG_ON(!RB_EMPTY_ROOT(&clp->cl_state_owners));
 	if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
 		nfs_idmap_delete(clp);
 #endif