1 files changed, 24 insertions, 6 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index e112d1a5dab..7eb36c53f4b 100644
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -1554,7 +1554,7 @@ void blk_plug_device(request_queue_t *q)
 	 * don't plug a stopped queue, it must be paired with blk_start_queue()
 	 * which will restart the queueing
 	 */
-	if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags))
+	if (blk_queue_stopped(q))
 		return;
 
 	if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) {
@@ -1587,7 +1587,7 @@ EXPORT_SYMBOL(blk_remove_plug);
  */
 void __generic_unplug_device(request_queue_t *q)
 {
-	if (unlikely(test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)))
+	if (unlikely(blk_queue_stopped(q)))
 		return;
 
 	if (!blk_remove_plug(q))
@@ -1732,8 +1732,21 @@ void blk_run_queue(struct request_queue *q)
 
 	spin_lock_irqsave(q->queue_lock, flags);
 	blk_remove_plug(q);
-	if (!elv_queue_empty(q))
-		q->request_fn(q);
+
+	/*
+	 * Only recurse once to avoid overrunning the stack, let the unplug
+	 * handling reinvoke the handler shortly if we already got there.
+	 */
+	if (!elv_queue_empty(q)) {
+		if (!test_and_set_bit(QUEUE_FLAG_REENTER, &q->queue_flags)) {
+			q->request_fn(q);
+			clear_bit(QUEUE_FLAG_REENTER, &q->queue_flags);
+		} else {
+			blk_plug_device(q);
+			kblockd_schedule_work(&q->unplug_work);
+		}
+	}
+
 	spin_unlock_irqrestore(q->queue_lock, flags);
 }
 EXPORT_SYMBOL(blk_run_queue);
@@ -3385,7 +3398,7 @@ static int blk_cpu_notify(struct notifier_block *self, unsigned long action,
 }
 
 
-static struct notifier_block __devinitdata blk_cpu_notifier = {
+static struct notifier_block blk_cpu_notifier = {
 	.notifier_call	= blk_cpu_notify,
 };
 
@@ -3439,7 +3452,12 @@ void end_that_request_last(struct request *req, int uptodate)
 	if (unlikely(laptop_mode) && blk_fs_request(req))
 		laptop_io_completion();
 
-	if (disk && blk_fs_request(req)) {
+	/*
+	 * Account IO completion.  bar_rq isn't accounted as a normal
+	 * IO on queueing nor completion.  Accounting the containing
+	 * request is enough.
+	 */
+	if (disk && blk_fs_request(req) && req != &req->q->bar_rq) {
 		unsigned long duration = jiffies - req->start_time;
 		const int rw = rq_data_dir(req);