md: remove bio_alloc_mddev

bio_alloc_mddev is never called with a NULL mddev, and ->bio_set is
initialized in md_run, so it always must be initialized as well. Just
open code the remaining call to bio_alloc_bioset.

Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Song Liu <[e-mail]>
Reviewed-by: Johannes Thumshirn <[e-mail]>
Reviewed-by: Chaitanya Kulkarni <[e-mail]>
Acked-by: Damien Le Moal <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/md/md.c

···
  */
 static bool create_on_open = true;
 
-struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
-			    struct mddev *mddev)
-{
-	if (!mddev || !bioset_initialized(&mddev->bio_set))
-		return bio_alloc(gfp_mask, nr_iovecs);
-
-	return bio_alloc_bioset(gfp_mask, nr_iovecs, &mddev->bio_set);
-}
-EXPORT_SYMBOL_GPL(bio_alloc_mddev);
-
 static struct bio *md_bio_alloc_sync(struct mddev *mddev)
 {
 	if (!mddev || !bioset_initialized(&mddev->sync_set))
···
 			atomic_inc(&rdev->nr_pending);
 			atomic_inc(&rdev->nr_pending);
 			rcu_read_unlock();
-			bi = bio_alloc_mddev(GFP_NOIO, 0, mddev);
+			bi = bio_alloc_bioset(GFP_NOIO, 0, &mddev->bio_set);
 			bi->bi_end_io = md_end_flush;
 			bi->bi_private = rdev;
 			bio_set_dev(bi, rdev->bdev);

drivers/md/md.h

···
 extern void md_handle_request(struct mddev *mddev, struct bio *bio);
 extern void mddev_suspend(struct mddev *mddev);
 extern void mddev_resume(struct mddev *mddev);
-extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
-				   struct mddev *mddev);
 
 extern void md_reload_sb(struct mddev *mddev, int raid_disk);
 extern void md_update_sb(struct mddev *mddev, int force);

drivers/md/raid1.c

···
 	int i = 0;
 	struct bio *behind_bio = NULL;
 
-	behind_bio = bio_alloc_mddev(GFP_NOIO, vcnt, r1_bio->mddev);
+	behind_bio = bio_alloc_bioset(GFP_NOIO, vcnt, &r1_bio->mddev->bio_set);
 	if (!behind_bio)
 		return;
 

drivers/md/raid10.c

···
 		return sectors_done;
 	}
 
-	read_bio = bio_alloc_mddev(GFP_KERNEL, RESYNC_PAGES, mddev);
+	read_bio = bio_alloc_bioset(GFP_KERNEL, RESYNC_PAGES, &mddev->bio_set);
 
 	bio_set_dev(read_bio, rdev->bdev);
 	read_bio->bi_iter.bi_sector = (r10_bio->devs[r10_bio->read_slot].addr