md: don't detour through bd_contains for the gendisk

bd_disk is set on all block devices, including those for partitions.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/md.c

@@ -8444,7 +8444,7 @@ static int is_mddev_idle(struct mddev *mddev, int init)
 	idle = 1;
 	rcu_read_lock();
 	rdev_for_each_rcu(rdev, mddev) {
-		struct gendisk *disk = rdev->bdev->bd_contains->bd_disk;
+		struct gendisk *disk = rdev->bdev->bd_disk;
 		curr_events = (int)part_stat_read_accum(&disk->part0, sectors) -
 			      atomic_read(&disk->sync_io);
 		/* sync IO will cause sync_io to increase before the disk_stats

drivers/md/md.h

@@ -551,7 +551,7 @@ extern void mddev_unlock(struct mddev *mddev);
 
 static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
 {
-	atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
+	atomic_add(nr_sectors, &bdev->bd_disk->sync_io);
 }
 
 static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)