1 files changed, 17 insertions, 10 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 838a5e31394c..d55cfcae2ef1 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -297,20 +297,12 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
 {
         int background_ratio;           /* Percentages */
         int dirty_ratio;
-        int unmapped_ratio;
         long background;
         long dirty;
         unsigned long available_memory = determine_dirtyable_memory();
         struct task_struct *tsk;
 
-        unmapped_ratio = 100 - ((global_page_state(NR_FILE_MAPPED) +
-                                global_page_state(NR_ANON_PAGES)) * 100) /
-                                        available_memory;
-
         dirty_ratio = vm_dirty_ratio;
-        if (dirty_ratio > unmapped_ratio / 2)
-                dirty_ratio = unmapped_ratio / 2;
-
         if (dirty_ratio < 5)
                 dirty_ratio = 5;
 
@@ -355,8 +347,8 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
  */
 static void balance_dirty_pages(struct address_space *mapping)
 {
-        long bdi_nr_reclaimable;
-        long bdi_nr_writeback;
+        long nr_reclaimable, bdi_nr_reclaimable;
+        long nr_writeback, bdi_nr_writeback;
         long background_thresh;
         long dirty_thresh;
         long bdi_thresh;
@@ -376,11 +368,26 @@ static void balance_dirty_pages(struct address_space *mapping)
 
                 get_dirty_limits(&background_thresh, &dirty_thresh,
                                 &bdi_thresh, bdi);
+
+                nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
+                                        global_page_state(NR_UNSTABLE_NFS);
+                nr_writeback = global_page_state(NR_WRITEBACK);
+
                 bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
                 bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
+
                 if (bdi_nr_reclaimable + bdi_nr_writeback <= bdi_thresh)
                         break;
 
+                /*
+                 * Throttle it only when the background writeback cannot
+                 * catch-up. This avoids (excessively) small writeouts
+                 * when the bdi limits are ramping up.
+                 */
+                if (nr_reclaimable + nr_writeback <
+                                (background_thresh + dirty_thresh) / 2)
+                        break;
+
                 if (!bdi->dirty_exceeded)
                         bdi->dirty_exceeded = 1;