block: call rq_qos_done() before ref check in batch completions

We need to call rq_qos_done() regardless of whether or not we're freeing
the request or not, as the reference count doesn't cover the IO completion
tracking.

Fixes: f794f33 ("block: add support for blk_mq_end_request_batch()")
Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reported-by: Kenneth R. Crudup <kenny@panix.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: axboe

block/blk-mq.c

@@ -860,13 +860,14 @@ void blk_mq_end_request_batch(struct io_comp_batch *iob)
 		if (iob->need_ts)
 			__blk_mq_end_request_acct(rq, now);
 
+		rq_qos_done(rq->q, rq);
+
 		WRITE_ONCE(rq->state, MQ_RQ_IDLE);
 		if (!refcount_dec_and_test(&rq->ref))
 			continue;
 
 		blk_crypto_free_request(rq);
 		blk_pm_mark_last_busy(rq);
-		rq_qos_done(rq->q, rq);
 
 		if (nr_tags == TAG_COMP_BATCH || cur_hctx != rq->mq_hctx) {
 			if (cur_hctx)