1 files changed, 26 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index e5b6b1190a95..4ac077f4269c 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -243,6 +243,29 @@ static void task_dirty_limit(struct task_struct *tsk, long *pdirty)
 }
 
 /*
+ *
+ */
+static DEFINE_SPINLOCK(bdi_lock);
+static unsigned int bdi_min_ratio;
+
+int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
+{
+        int ret = 0;
+        unsigned long flags;
+
+        spin_lock_irqsave(&bdi_lock, flags);
+        min_ratio -= bdi->min_ratio;
+        if (bdi_min_ratio + min_ratio < 100) {
+                bdi_min_ratio += min_ratio;
+                bdi->min_ratio += min_ratio;
+        } else
+                ret = -EINVAL;
+        spin_unlock_irqrestore(&bdi_lock, flags);
+
+        return ret;
+}
+
+/*
  * Work out the current dirty-memory clamping and background writeout
  * thresholds.
  *
@@ -330,7 +353,7 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
         *pdirty = dirty;
 
         if (bdi) {
-                u64 bdi_dirty = dirty;
+                u64 bdi_dirty;
                 long numerator, denominator;
 
                 /*
@@ -338,8 +361,10 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
                  */
                 bdi_writeout_fraction(bdi, &numerator, &denominator);
 
+                bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100;
                 bdi_dirty *= numerator;
                 do_div(bdi_dirty, denominator);
+                bdi_dirty += (dirty * bdi->min_ratio) / 100;
 
                 *pbdi_dirty = bdi_dirty;
                 clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty);