diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index c18c008..76e8903 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -70,6 +70,7 @@
 struct bdi_writeback;
 int inode_wait(void *);
 void writeback_inodes_sb(struct super_block *);
+int writeback_inodes_sb_if_idle(struct super_block *);
 void sync_inodes_sb(struct super_block *);
 void writeback_inodes_wbc(struct writeback_control *wbc);
 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);