drbd_req.c: use part_[inc|dec]_in_flight()

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index d09aac4..de81ab7 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -39,8 +39,8 @@
 	cpu = part_stat_lock();
 	part_stat_inc(cpu, &mdev->vdisk->part0, ios[rw]);
 	part_stat_add(cpu, &mdev->vdisk->part0, sectors[rw], bio_sectors(bio));
+	part_inc_in_flight(&mdev->vdisk->part0, rw);
 	part_stat_unlock();
-	mdev->vdisk->part0.in_flight[rw]++;
 }
 
 /* Update disk stats when completing request upwards */
@@ -52,8 +52,8 @@
 	cpu = part_stat_lock();
 	part_stat_add(cpu, &mdev->vdisk->part0, ticks[rw], duration);
 	part_round_stats(cpu, &mdev->vdisk->part0);
+	part_dec_in_flight(&mdev->vdisk->part0, rw);
 	part_stat_unlock();
-	mdev->vdisk->part0.in_flight[rw]--;
 }
 
 static void _req_is_done(struct drbd_conf *mdev, struct drbd_request *req, const int rw)