sunrpc: Add _add_rpc_iostats() to add rpc_iostats metrics

Add a helper function to add the metrics in two rpc_iostats structures.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

net/sunrpc/stats.c

@@ -208,6 +208,18 @@ static void _print_name(struct seq_file *seq, unsigned int op,
 		seq_printf(seq, "\t%12u: ", op);
 }
 
+static void _add_rpc_iostats(struct rpc_iostats *a, struct rpc_iostats *b)
+{
+	a->om_ops += b->om_ops;
+	a->om_ntrans += b->om_ntrans;
+	a->om_timeouts += b->om_timeouts;
+	a->om_bytes_sent += b->om_bytes_sent;
+	a->om_bytes_recv += b->om_bytes_recv;
+	a->om_queue = ktime_add(a->om_queue, b->om_queue);
+	a->om_rtt = ktime_add(a->om_rtt, b->om_rtt);
+	a->om_execute = ktime_add(a->om_execute, b->om_execute);
+}
+
 static void _print_rpc_iostats(struct seq_file *seq, struct rpc_iostats *stats,
 			       int op, const struct rpc_procinfo *procs)
 {