block: fixup block IO unplug trace call

It was removed with the on-stack plugging, readd it and track the
depth of requests added when flushing the plug.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index eeaca0998df..d20ce1e849c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2668,12 +2668,19 @@ static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b)
         return !(rqa->q <= rqb->q);
 }
 
+static void queue_unplugged(struct request_queue *q, unsigned int depth)
+{
+        trace_block_unplug_io(q, depth);
+        __blk_run_queue(q, false);
+}
+
 static void flush_plug_list(struct blk_plug *plug)
 {
         struct request_queue *q;
         unsigned long flags;
         struct request *rq;
         LIST_HEAD(list);
+        unsigned int depth;
 
         BUG_ON(plug->magic != PLUG_MAGIC);
 
@@ -2688,6 +2695,7 @@ static void flush_plug_list(struct blk_plug *plug)
         }
 
         q = NULL;
+        depth = 0;
         local_irq_save(flags);
         while (!list_empty(&list)) {
                 rq = list_entry_rq(list.next);
@@ -2696,10 +2704,11 @@ static void flush_plug_list(struct blk_plug *plug)
                 BUG_ON(!rq->q);
                 if (rq->q != q) {
                         if (q) {
-                                __blk_run_queue(q, false);
+                                queue_unplugged(q, depth);
                                 spin_unlock(q->queue_lock);
                         }
                         q = rq->q;
+                        depth = 0;
                         spin_lock(q->queue_lock);
                 }
                 rq->cmd_flags &= ~REQ_ON_PLUG;
@@ -2711,10 +2720,12 @@ static void flush_plug_list(struct blk_plug *plug)
                         __elv_add_request(q, rq, ELEVATOR_INSERT_FLUSH);
                 else
                         __elv_add_request(q, rq, ELEVATOR_INSERT_SORT_MERGE);
+
+                depth++;
         }
 
         if (q) {
-                __blk_run_queue(q, false);
+                queue_unplugged(q, depth);
                 spin_unlock(q->queue_lock);
         }