Add UNPLUG traces to all appropriate places

Added blk_unplug interface, allowing all invocations of unplugs to result
in a generated blktrace UNPLUG.

Signed-off-by: Alan D. Brunelle <Alan.Brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/ll_rw_blk.c

@@ -1621,15 +1621,7 @@ static void blk_backing_dev_unplug(struct backing_dev_info *bdi,
 {
 	struct request_queue *q = bdi->unplug_io_data;
 
-	/*
+	blk_unplug(q);
-	 * devices don't necessarily have an ->unplug_fn defined
-	 */
-	if (q->unplug_fn) {
-		blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
-					q->rq.count[READ] + q->rq.count[WRITE]);
-
-		q->unplug_fn(q);
-	}
 }
 
 static void blk_unplug_work(struct work_struct *work)
@@ -1653,6 +1645,20 @@ static void blk_unplug_timeout(unsigned long data)
 	kblockd_schedule_work(&q->unplug_work);
 }
 
+void blk_unplug(struct request_queue *q)
+{
+	/*
+	 * devices don't necessarily have an ->unplug_fn defined
+	 */
+	if (q->unplug_fn) {
+		blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL,
+					q->rq.count[READ] + q->rq.count[WRITE]);
+
+		q->unplug_fn(q);
+	}
+}
+EXPORT_SYMBOL(blk_unplug);
+
 /**
  * blk_start_queue - restart a previously stopped queue
  * @q:    The &struct request_queue in question

drivers/md/bitmap.c

@@ -1207,8 +1207,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
 			prepare_to_wait(&bitmap->overflow_wait, &__wait,
 					TASK_UNINTERRUPTIBLE);
 			spin_unlock_irq(&bitmap->lock);
-			bitmap->mddev->queue
+			blk_unplug(bitmap->mddev->queue);
-				->unplug_fn(bitmap->mddev->queue);
 			schedule();
 			finish_wait(&bitmap->overflow_wait, &__wait);
 			continue;

drivers/md/dm-table.c

@@ -1000,8 +1000,7 @@ void dm_table_unplug_all(struct dm_table *t)
 		struct dm_dev *dd = list_entry(d, struct dm_dev, list);
 		struct request_queue *q = bdev_get_queue(dd->bdev);
 
-		if (q->unplug_fn)
+		blk_unplug(q);
-			q->unplug_fn(q);
 	}
 }
 

drivers/md/linear.c

@@ -87,8 +87,7 @@ static void linear_unplug(struct request_queue *q)
 
 	for (i=0; i < mddev->raid_disks; i++) {
 		struct request_queue *r_queue = bdev_get_queue(conf->disks[i].rdev->bdev);
-		if (r_queue->unplug_fn)
+		blk_unplug(r_queue);
-			r_queue->unplug_fn(r_queue);
 	}
 }
 

drivers/md/md.c

@@ -5445,7 +5445,7 @@ void md_do_sync(mddev_t *mddev)
 		 * about not overloading the IO subsystem. (things like an
 		 * e2fsck being done on the RAID array should execute fast)
 		 */
-		mddev->queue->unplug_fn(mddev->queue);
+		blk_unplug(mddev->queue);
 		cond_resched();
 
 		currspeed = ((unsigned long)(io_sectors-mddev->resync_mark_cnt))/2
@@ -5464,7 +5464,7 @@ void md_do_sync(mddev_t *mddev)
 	 * this also signals 'finished resyncing' to md_stop
 	 */
  out:
-	mddev->queue->unplug_fn(mddev->queue);
+	blk_unplug(mddev->queue);
 
 	wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
 

drivers/md/multipath.c

@@ -125,8 +125,7 @@ static void unplug_slaves(mddev_t *mddev)
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 
-			if (r_queue->unplug_fn)
+			blk_unplug(r_queue);
-				r_queue->unplug_fn(r_queue);
 
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();

drivers/md/raid0.c

@@ -35,8 +35,7 @@ static void raid0_unplug(struct request_queue *q)
 	for (i=0; i<mddev->raid_disks; i++) {
 		struct request_queue *r_queue = bdev_get_queue(devlist[i]->bdev);
 
-		if (r_queue->unplug_fn)
+		blk_unplug(r_queue);
-			r_queue->unplug_fn(r_queue);
 	}
 }
 

drivers/md/raid1.c

@@ -549,8 +549,7 @@ static void unplug_slaves(mddev_t *mddev)
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 
-			if (r_queue->unplug_fn)
+			blk_unplug(r_queue);
-				r_queue->unplug_fn(r_queue);
 
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();

drivers/md/raid10.c

@@ -593,8 +593,7 @@ static void unplug_slaves(mddev_t *mddev)
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 
-			if (r_queue->unplug_fn)
+			blk_unplug(r_queue);
-				r_queue->unplug_fn(r_queue);
 
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();

drivers/md/raid5.c

@@ -3186,8 +3186,7 @@ static void unplug_slaves(mddev_t *mddev)
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
 
-			if (r_queue->unplug_fn)
+			blk_unplug(r_queue);
-				r_queue->unplug_fn(r_queue);
 
 			rdev_dec_pending(rdev, mddev);
 			rcu_read_lock();

include/linux/blkdev.h

@@ -697,6 +697,7 @@ extern int blk_execute_rq(struct request_queue *, struct gendisk *,
 extern void blk_execute_rq_nowait(struct request_queue *, struct gendisk *,
 				  struct request *, int, rq_end_io_fn *);
 extern int blk_verify_command(unsigned char *, int);
+extern void blk_unplug(struct request_queue *q);
 
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {