nullb: use blk_queue_set_zoned() to setup zoned devices

Use blk_queue_set_zoned() to set a nullb device zone model instead of
directly assigning the device queue zoned limit. This initialization of
the devicve zoned model as well as the setup of the queue flag
QUEUE_FLAG_ZONE_RESETALL and of the device queue elevator feature are
moved from null_init_zoned_dev() to null_register_zoned_dev() so that
the initialization of the queue limits is done when the gendisk of the
nullb device is available.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@edc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk/zoned.c

@@ -146,10 +146,6 @@ int null_init_zoned_dev(struct nullb_device *dev, struct request_queue *q)
 		sector += dev->zone_size_sects;
 	}
 
-	q->limits.zoned = BLK_ZONED_HM;
-	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
-	blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
-
 	return 0;
 }
 
@@ -158,6 +154,10 @@ int null_register_zoned_dev(struct nullb *nullb)
 	struct nullb_device *dev = nullb->dev;
 	struct request_queue *q = nullb->q;
 
+	blk_queue_set_zoned(nullb->disk, BLK_ZONED_HM);
+	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
+	blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
+
 	if (queue_is_mq(q)) {
 		int ret = blk_revalidate_disk_zones(nullb->disk, NULL);