blk-mq: Reduce the number of if-statements in blk_mq_mark_tag_wait()

This patch does not change any functionality but makes the
blk_mq_mark_tag_wait() code slightly easier to read.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -1104,15 +1104,25 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
 				 struct request *rq)
 {
 	struct blk_mq_hw_ctx *this_hctx = *hctx;
-	bool shared_tags = (this_hctx->flags & BLK_MQ_F_TAG_SHARED) != 0;
 	struct sbq_wait_state *ws;
 	wait_queue_entry_t *wait;
 	bool ret;
 
-	if (!shared_tags) {
+	if (!(this_hctx->flags & BLK_MQ_F_TAG_SHARED)) {
 		if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state))
 			set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state);
-	} else {
+
+		/*
+		 * It's possible that a tag was freed in the window between the
+		 * allocation failure and adding the hardware queue to the wait
+		 * queue.
+		 *
+		 * Don't clear RESTART here, someone else could have set it.
+		 * At most this will cost an extra queue run.
+		 */
+		return blk_mq_get_driver_tag(rq, hctx, false);
+	}
+
 	wait = &this_hctx->dispatch_wait;
 	if (!list_empty_careful(&wait->entry))
 		return false;
@@ -1125,7 +1135,6 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
 
 	ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx);
 	add_wait_queue(&ws->wait, wait);
-	}
 
 	/*
 	 * It's possible that a tag was freed in the window between the
@@ -1133,14 +1142,6 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
 	 * queue.
 	 */
 	ret = blk_mq_get_driver_tag(rq, hctx, false);
-
-	if (!shared_tags) {
-		/*
-		 * Don't clear RESTART here, someone else could have set it.
-		 * At most this will cost an extra queue run.
-		 */
-		return ret;
-	} else {
 	if (!ret) {
 		spin_unlock(&this_hctx->lock);
 		return false;
@@ -1154,8 +1155,8 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx,
 	list_del_init(&wait->entry);
 	spin_unlock_irq(&ws->wait.lock);
 	spin_unlock(&this_hctx->lock);
+
 	return true;
-	}
 }
 
 bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list,