1 files changed, 23 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index c8ac8cea67dc..9d9a896fa7b5 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1740,6 +1740,29 @@ void balance_dirty_pages_ratelimited(struct address_space *mapping)
 }
 EXPORT_SYMBOL(balance_dirty_pages_ratelimited);
 
+/**
+ * wb_over_bg_thresh - does @wb need to be written back?
+ * @wb: bdi_writeback of interest
+ *
+ * Determines whether background writeback should keep writing @wb or it's
+ * clean enough.  Returns %true if writeback should continue.
+ */
+bool wb_over_bg_thresh(struct bdi_writeback *wb)
+{
+	unsigned long background_thresh, dirty_thresh;
+
+	global_dirty_limits(&background_thresh, &dirty_thresh);
+
+	if (global_page_state(NR_FILE_DIRTY) +
+	    global_page_state(NR_UNSTABLE_NFS) > background_thresh)
+		return true;
+
+	if (wb_stat(wb, WB_RECLAIMABLE) > wb_calc_thresh(wb, background_thresh))
+		return true;
+
+	return false;
+}
+
 void throttle_vm_writeout(gfp_t gfp_mask)
 {
 	unsigned long background_thresh;