1 files changed, 24 insertions, 6 deletions

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index e112d1a5dab6..7eb36c53f4b7 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);