diff --git a/[refs] b/[refs]
index c0eb842c0d0a..0ba99db3161e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 16b56cf4b8a0fa9acc21bd2ad19839b917999b96
+refs/heads/master: 74ce002d9aee23031b4967e1dd1c1966ddc60749
diff --git a/trunk/fs/fs-writeback.c b/trunk/fs/fs-writeback.c
index 97d2951bd4d1..b5aae4bd0aca 100644
--- a/trunk/fs/fs-writeback.c
+++ b/trunk/fs/fs-writeback.c
@@ -721,6 +721,10 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
 		return 0;
 
 	wb->last_old_flush = jiffies;
+	/*
+	 * Add in the number of potentially dirty inodes, because each inode
+	 * write can dirty pagecache in the underlying blockdev.
+	 */
 	nr_pages = global_page_state(NR_FILE_DIRTY) +
 			global_page_state(NR_UNSTABLE_NFS) +
 			(inodes_stat.nr_inodes - inodes_stat.nr_unused);