2 files changed, 40 insertions, 5 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index baef5fc7cff8..e0aa4dad6742 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -92,6 +92,8 @@ struct cfq_data {
         struct cfq_queue *active_queue;
         struct cfq_io_context *active_cic;
 
+        struct cfq_queue *async_cfqq[IOPRIO_BE_NR];
+
         struct timer_list idle_class_timer;
 
         sector_t last_position;
@@ -1351,8 +1353,8 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)
 }
 
 static struct cfq_queue *
-cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
-              gfp_t gfp_mask)
+cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
+                     struct task_struct *tsk, gfp_t gfp_mask)
 {
         struct cfq_queue *cfqq, *new_cfqq = NULL;
         struct cfq_io_context *cic;
@@ -1405,12 +1407,35 @@ retry:
         if (new_cfqq)
                 kmem_cache_free(cfq_pool, new_cfqq);
 
-        atomic_inc(&cfqq->ref);
 out:
         WARN_ON((gfp_mask & __GFP_WAIT) && !cfqq);
         return cfqq;
 }
 
+static struct cfq_queue *
+cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
+              gfp_t gfp_mask)
+{
+        const int ioprio = task_ioprio(tsk);
+        struct cfq_queue *cfqq = NULL;
+
+        if (!is_sync)
+                cfqq = cfqd->async_cfqq[ioprio];
+        if (!cfqq)
+                cfqq = cfq_find_alloc_queue(cfqd, is_sync, tsk, gfp_mask);
+
+        /*
+         * pin the queue now that it's allocated, scheduler exit will prune it
+         */
+        if (!is_sync && !cfqd->async_cfqq[ioprio]) {
+                atomic_inc(&cfqq->ref);
+                cfqd->async_cfqq[ioprio] = cfqq;
+        }
+
+        atomic_inc(&cfqq->ref);
+        return cfqq;
+}
+
 /*
  * We drop cfq io contexts lazily, so we may find a dead one.
  */
@@ -2019,6 +2044,7 @@ static void cfq_exit_queue(elevator_t *e)
 {
         struct cfq_data *cfqd = e->elevator_data;
         request_queue_t *q = cfqd->queue;
+        int i;
 
         cfq_shutdown_timer_wq(cfqd);
 
@@ -2035,6 +2061,13 @@ static void cfq_exit_queue(elevator_t *e)
                 __cfq_exit_single_io_context(cfqd, cic);
         }
 
+        /*
+         * Put the async queues
+         */
+        for (i = 0; i < IOPRIO_BE_NR; i++)
+                if (cfqd->async_cfqq[i])        
+                        cfq_put_queue(cfqd->async_cfqq[i]);
+
         spin_unlock_irq(q->queue_lock);
 
         cfq_shutdown_timer_wq(cfqd);
diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index 8e2042b9d471..2eaa142cd061 100644
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -47,8 +47,10 @@ enum {
 #define IOPRIO_NORM     (4)
 static inline int task_ioprio(struct task_struct *task)
 {
-        WARN_ON(!ioprio_valid(task->ioprio));
-        return IOPRIO_PRIO_DATA(task->ioprio);
+        if (ioprio_valid(task->ioprio))
+                return IOPRIO_PRIO_DATA(task->ioprio);
+
+        return IOPRIO_NORM;
 }
 
 static inline int task_nice_ioprio(struct task_struct *task)