ublk_drv: Do not request ELEVATOR_F_ZBD_SEQ_WRITE elevator feature

With zone write plugging enabled at the block layer level, any zone
device can only ever see at most a single write operation per zone.
There is thus no need to request a block scheduler with strick per-zone
sequential write ordering control through the ELEVATOR_F_ZBD_SEQ_WRITE
feature. Removing this allows using a zoned ublk device with any
scheduler, including "none".
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20240408014128.205141-15-dlemoal@kernel.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/ublk_drv.c

@@ -249,8 +249,7 @@ static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
 static void ublk_dev_param_zoned_apply(struct ublk_device *ub)
 {
 	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, ub->ub_disk->queue);
-	blk_queue_required_elevator_features(ub->ub_disk->queue,
-					     ELEVATOR_F_ZBD_SEQ_WRITE);
+
 	ub->ub_disk->nr_zones = ublk_get_nr_zones(ub);
 }