md: fix up raid1/raid10 unplugging.

We just need to make sure that an unplug event wakes up the md
thread, which is exactly what mddev_check_plugged does.

Also remove some plug-related code that is no longer needed.

Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index c8e5dac..8e94626 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -634,12 +634,6 @@
 		spin_unlock_irq(&conf->device_lock);
 }
 
-static void md_kick_device(mddev_t *mddev)
-{
-	blk_flush_plug(current);
-	md_wakeup_thread(mddev->thread);
-}
-
 /* Barriers....
  * Sometimes we need to suspend IO while we do something else,
  * either some resync/recovery, or reconfigure the array.
@@ -669,15 +663,15 @@
 
 	/* Wait until no block IO is waiting (unless 'force') */
 	wait_event_lock_irq(conf->wait_barrier, force || !conf->nr_waiting,
-			    conf->resync_lock, md_kick_device(conf->mddev));
+			    conf->resync_lock, );
 
 	/* block any new IO from starting */
 	conf->barrier++;
 
-	/* No wait for all pending IO to complete */
+	/* Now wait for all pending IO to complete */
 	wait_event_lock_irq(conf->wait_barrier,
 			    !conf->nr_pending && conf->barrier < RESYNC_DEPTH,
-			    conf->resync_lock, md_kick_device(conf->mddev));
+			    conf->resync_lock, );
 
 	spin_unlock_irq(&conf->resync_lock);
 }
@@ -698,7 +692,7 @@
 		conf->nr_waiting++;
 		wait_event_lock_irq(conf->wait_barrier, !conf->barrier,
 				    conf->resync_lock,
-				    md_kick_device(conf->mddev));
+				    );
 		conf->nr_waiting--;
 	}
 	conf->nr_pending++;
@@ -734,8 +728,8 @@
 	wait_event_lock_irq(conf->wait_barrier,
 			    conf->nr_pending == conf->nr_queued+1,
 			    conf->resync_lock,
-			    ({ flush_pending_writes(conf);
-			       md_kick_device(conf->mddev); }));
+			    flush_pending_writes(conf));
+
 	spin_unlock_irq(&conf->resync_lock);
 }
 
@@ -762,6 +756,7 @@
 	const unsigned long do_fua = (bio->bi_rw & REQ_FUA);
 	unsigned long flags;
 	mdk_rdev_t *blocked_rdev;
+	int plugged;
 
 	if (unlikely(bio->bi_rw & REQ_FLUSH)) {
 		md_flush_request(mddev, bio);
@@ -870,6 +865,8 @@
 	 * inc refcount on their rdev.  Record them by setting
 	 * bios[x] to bio
 	 */
+	plugged = mddev_check_plugged(mddev);
+
 	raid10_find_phys(conf, r10_bio);
  retry_write:
 	blocked_rdev = NULL;
@@ -946,9 +943,8 @@
 	/* In case raid10d snuck in to freeze_array */
 	wake_up(&conf->wait_barrier);
 
-	if (do_sync || !mddev->bitmap)
+	if (do_sync || !mddev->bitmap || !plugged)
 		md_wakeup_thread(mddev->thread);
-
 	return 0;
 }