block: add queue_is_mq() helper

Various spots check for q->mq_ops being non-NULL, but provide
a helper to do this instead.

Where the ->mq_ops != NULL check is redundant, remove it.

Since mq == rq-based now that legacy is gone, get rid of the
queue_is_rq_based() and just use queue_is_mq() everywhere.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-core.c b/block/blk-core.c
index 92b6b20..0b684a5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -232,7 +232,7 @@ void blk_sync_queue(struct request_queue *q)
 	del_timer_sync(&q->timeout);
 	cancel_work_sync(&q->timeout_work);
 
-	if (q->mq_ops) {
+	if (queue_is_mq(q)) {
 		struct blk_mq_hw_ctx *hctx;
 		int i;
 
@@ -281,7 +281,7 @@ void blk_set_queue_dying(struct request_queue *q)
 	 */
 	blk_freeze_queue_start(q);
 
-	if (q->mq_ops)
+	if (queue_is_mq(q))
 		blk_mq_wake_waiters(q);
 
 	/* Make blk_queue_enter() reexamine the DYING flag. */
@@ -356,7 +356,7 @@ void blk_cleanup_queue(struct request_queue *q)
 	 * blk_freeze_queue() should be enough for cases of passthrough
 	 * request.
 	 */
-	if (q->mq_ops && blk_queue_init_done(q))
+	if (queue_is_mq(q) && blk_queue_init_done(q))
 		blk_mq_quiesce_queue(q);
 
 	/* for synchronous bio-based driver finish in-flight integrity i/o */
@@ -374,7 +374,7 @@ void blk_cleanup_queue(struct request_queue *q)
 
 	blk_exit_queue(q);
 
-	if (q->mq_ops)
+	if (queue_is_mq(q))
 		blk_mq_free_queue(q);
 
 	percpu_ref_exit(&q->q_usage_counter);
@@ -982,7 +982,7 @@ generic_make_request_checks(struct bio *bio)
 	 * For a REQ_NOWAIT based request, return -EOPNOTSUPP
 	 * if queue is not a request based queue.
 	 */
-	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q))
+	if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q))
 		goto not_supported;
 
 	if (should_fail_bio(bio))
@@ -1657,7 +1657,7 @@ EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
  */
 int blk_lld_busy(struct request_queue *q)
 {
-	if (q->mq_ops && q->mq_ops->busy)
+	if (queue_is_mq(q) && q->mq_ops->busy)
 		return q->mq_ops->busy(q);
 
 	return 0;