block/mq-deadline: Add two lockdep_assert_held() statements

Document the locking strategy by adding two lockdep_assert_held()
statements.

Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Himanshu Madhani <[email protected]>
Cc: Damien Le Moal <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Ming Lei <[email protected]>
Signed-off-by: Bart Van Assche <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

block/mq-deadline.c

@@ -279,6 +279,8 @@ static struct request *__dd_dispatch_request(struct deadline_data *dd)
 	bool reads, writes;
 	int data_dir;
 
+	lockdep_assert_held(&dd->lock);
+
 	if (!list_empty(&dd->dispatch)) {
 		rq = list_first_entry(&dd->dispatch, struct request, queuelist);
 		list_del_init(&rq->queuelist);
@@ -501,6 +503,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 	struct deadline_data *dd = q->elevator->elevator_data;
 	const int data_dir = rq_data_dir(rq);
 
+	lockdep_assert_held(&dd->lock);
+
 	/*
 	 * This may be a requeue of a write request that has locked its
 	 * target zone. If it is the case, this releases the zone lock.