diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index df1b7f1..66862f2 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -118,6 +118,9 @@
 unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
 			       unsigned long dirty);
 
+void __bdi_update_bandwidth(struct backing_dev_info *bdi,
+			    unsigned long start_time);
+
 void page_writeback_init(void);
 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 					unsigned long nr_pages_dirtied);