block: remove export for blk_queue_bio

With commit ff36ab345 ("dm: remove request-based logic from
make_request_fn wrapper") DM no longer calls blk_queue_bio() directly,
so remove its export.  Doing so required a forward declaration in
blk-core.c.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 7871603..03b5f8d 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -734,6 +734,8 @@
 }
 EXPORT_SYMBOL(blk_init_queue_node);
 
+static void blk_queue_bio(struct request_queue *q, struct bio *bio);
+
 struct request_queue *
 blk_init_allocated_queue(struct request_queue *q, request_fn_proc *rfn,
 			 spinlock_t *lock)
@@ -1578,7 +1580,7 @@
 	blk_rq_bio_prep(req->q, req, bio);
 }
 
-void blk_queue_bio(struct request_queue *q, struct bio *bio)
+static void blk_queue_bio(struct request_queue *q, struct bio *bio)
 {
 	const bool sync = !!(bio->bi_rw & REQ_SYNC);
 	struct blk_plug *plug;
@@ -1686,7 +1688,6 @@
 		spin_unlock_irq(q->queue_lock);
 	}
 }
-EXPORT_SYMBOL_GPL(blk_queue_bio);	/* for device mapper only */
 
 /*
  * If bio->bi_dev is a partition, remap the location
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 7f9a516..5d93a66 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -821,8 +821,6 @@
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			 struct scsi_ioctl_command __user *);
 
-extern void blk_queue_bio(struct request_queue *q, struct bio *bio);
-
 /*
  * A queue has just exitted congestion.  Note this in the global counter of
  * congested queues, and wake up anyone who was waiting for requests to be