diff --git a/sys/vm/vm_object.h b/sys/vm/vm_object.h
--- a/sys/vm/vm_object.h
+++ b/sys/vm/vm_object.h
@@ -363,6 +363,7 @@
 void vm_object_destroy (vm_object_t);
 void vm_object_terminate (vm_object_t);
 void vm_object_set_writeable_dirty (vm_object_t);
+void vm_object_set_writeable_dirty_count (vm_object_t, int);
 void vm_object_set_writeable_dirty_(vm_object_t object);
 bool vm_object_mightbedirty(vm_object_t object);
 bool vm_object_mightbedirty_(vm_object_t object);
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -2337,6 +2337,13 @@
 	return (TRUE);
 }
 
+void
+vm_object_set_writeable_dirty_count(vm_object_t object, int count)
+{
+	MPASS(count > 0);
+	atomic_add_int(&object->generation, count);
+}
+
 void
 vm_object_set_writeable_dirty_(vm_object_t object)
 {