1 files changed, 36 insertions, 3 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index baef5fc..e0aa4da 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);