1 files changed, 19 insertions, 12 deletions

diff --git a/mm/pdflush.c b/mm/pdflush.c
index 235ac440c44e..f2caf96993f8 100644
--- a/mm/pdflush.c
+++ b/mm/pdflush.c
@@ -58,6 +58,14 @@ static DEFINE_SPINLOCK(pdflush_lock);
 int nr_pdflush_threads = 0;
 
 /*
+ * The max/min number of pdflush threads. R/W by sysctl at
+ * /proc/sys/vm/nr_pdflush_threads_max/min
+ */
+int nr_pdflush_threads_max __read_mostly = MAX_PDFLUSH_THREADS;
+int nr_pdflush_threads_min __read_mostly = MIN_PDFLUSH_THREADS;
+
+
+/*
  * The time at which the pdflush thread pool last went empty
  */
 static unsigned long last_empty_jifs;
@@ -68,7 +76,7 @@ static unsigned long last_empty_jifs;
  * Thread pool management algorithm:
  * 
  * - The minimum and maximum number of pdflush instances are bound
- *   by MIN_PDFLUSH_THREADS and MAX_PDFLUSH_THREADS.
+ *   by nr_pdflush_threads_min and nr_pdflush_threads_max.
  * 
  * - If there have been no idle pdflush instances for 1 second, create
  *   a new one.
@@ -134,14 +142,13 @@ static int __pdflush(struct pdflush_work *my_work)
                  * To throttle creation, we reset last_empty_jifs.
                  */
                 if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
-                        if (list_empty(&pdflush_list)) {
-                                if (nr_pdflush_threads < MAX_PDFLUSH_THREADS) {
-                                        last_empty_jifs = jiffies;
-                                        nr_pdflush_threads++;
-                                        spin_unlock_irq(&pdflush_lock);
-                                        start_one_pdflush_thread();
-                                        spin_lock_irq(&pdflush_lock);
-                                }
+                        if (list_empty(&pdflush_list) &&
+                            nr_pdflush_threads < nr_pdflush_threads_max) {
+                                last_empty_jifs = jiffies;
+                                nr_pdflush_threads++;
+                                spin_unlock_irq(&pdflush_lock);
+                                start_one_pdflush_thread();
+                                spin_lock_irq(&pdflush_lock);
                         }
                 }
 
@@ -153,7 +160,7 @@ static int __pdflush(struct pdflush_work *my_work)
                  */
                 if (list_empty(&pdflush_list))
                         continue;
-                if (nr_pdflush_threads <= MIN_PDFLUSH_THREADS)
+                if (nr_pdflush_threads <= nr_pdflush_threads_min)
                         continue;
                 pdf = list_entry(pdflush_list.prev, struct pdflush_work, list);
                 if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) {
@@ -259,9 +266,9 @@ static int __init pdflush_init(void)
          * Pre-set nr_pdflush_threads...  If we fail to create,
          * the count will be decremented.
          */
-        nr_pdflush_threads = MIN_PDFLUSH_THREADS;
+        nr_pdflush_threads = nr_pdflush_threads_min;
 
-        for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
+        for (i = 0; i < nr_pdflush_threads_min; i++)
                 start_one_pdflush_thread();
         return 0;
 }