blk-mq: change blk_mq_queue_busy() to blk_mq_queue_inflight()

There's a single user of this function, dm, and dm just wants
to check if IO is inflight, not that it's just allocated.

This fixes a hang with srp/002 in blktests with dm, where it tries
to suspend but waits for inflight IO to finish first. As it checks
for just allocated requests, this fails.
Tested-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -805,14 +805,14 @@ struct request *blk_mq_tag_to_rq(struct blk_mq_tags *tags, unsigned int tag)
 }
 EXPORT_SYMBOL(blk_mq_tag_to_rq);
 
-static bool blk_mq_check_busy(struct blk_mq_hw_ctx *hctx, struct request *rq,
+static bool blk_mq_rq_inflight(struct blk_mq_hw_ctx *hctx, struct request *rq,
 			       void *priv, bool reserved)
 {
 	/*
-	 * If we find a request, we know the queue is busy. Return false
-	 * to stop the iteration.
+	 * If we find a request that is inflight and the queue matches,
+	 * we know the queue is busy. Return false to stop the iteration.
 	 */
-	if (rq->q == hctx->queue) {
+	if (rq->state == MQ_RQ_IN_FLIGHT && rq->q == hctx->queue) {
 		bool *busy = priv;
 
 		*busy = true;
@@ -822,14 +822,14 @@ static bool blk_mq_check_busy(struct blk_mq_hw_ctx *hctx, struct request *rq,
 	return true;
 }
 
-bool blk_mq_queue_busy(struct request_queue *q)
+bool blk_mq_queue_inflight(struct request_queue *q)
 {
 	bool busy = false;
 
-	blk_mq_queue_tag_busy_iter(q, blk_mq_check_busy, &busy);
+	blk_mq_queue_tag_busy_iter(q, blk_mq_rq_inflight, &busy);
 	return busy;
 }
-EXPORT_SYMBOL_GPL(blk_mq_queue_busy);
+EXPORT_SYMBOL_GPL(blk_mq_queue_inflight);
 
 static void blk_mq_rq_timed_out(struct request *req, bool reserved)
 {

drivers/md/dm.c

@@ -663,7 +663,7 @@ static bool md_in_flight_bios(struct mapped_device *md)
 static bool md_in_flight(struct mapped_device *md)
 {
 	if (queue_is_mq(md->queue))
-		return blk_mq_queue_busy(md->queue);
+		return blk_mq_queue_inflight(md->queue);
 	else
 		return md_in_flight_bios(md);
 }

include/linux/blk-mq.h

@@ -257,7 +257,7 @@ void blk_mq_flush_plug_list(struct blk_plug *plug, bool from_schedule);
 void blk_mq_free_request(struct request *rq);
 bool blk_mq_can_queue(struct blk_mq_hw_ctx *);
 
-bool blk_mq_queue_busy(struct request_queue *q);
+bool blk_mq_queue_inflight(struct request_queue *q);
 
 enum {
 	/* return when out of requests */