[PATCH v7 15/28] null_blk: Do not request ELEVATOR_F_ZBD_SEQ_WRITE elevator feature

[Damien Le Moal]

With zone write plugging enabled at the block layer level, a zoned
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 null_blk device with any
scheduler, including "none".

Signed-off-by: Damien Le Moal <dlemoal at kernel.org>
Reviewed-by: Hannes Reinecke <hare at suse.de>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Bart Van Assche <bvanassche at acm.org>
Reviewed-by: Chaitanya Kulkarni <kch at nvidia.com>
Tested-by: Hans Holmberg <hans.holmberg at wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher at wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen at oracle.com>
---
 drivers/block/null_blk/zoned.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/block/null_blk/zoned.c b/drivers/block/null_blk/zoned.c
index 1689e2584104..8e217f8fadcd 100644
--- a/drivers/block/null_blk/zoned.c
+++ b/drivers/block/null_blk/zoned.c
@@ -165,7 +165,6 @@ int null_register_zoned_dev(struct nullb *nullb)
 	struct request_queue *q = nullb->q;
 
 	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
-	blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
 	nullb->disk->nr_zones = bdev_nr_zones(nullb->disk->part0);
 	return blk_revalidate_disk_zones(nullb->disk, NULL);
 }
-- 
2.44.0