[PATCH v10 08/18] scsi: sd_zbc: Only require an I/O scheduler if needed

Bart Van Assche
2023-08-18T19:47:13Z

An I/O scheduler that serializes zoned writes is only needed if the SCSI
LLD does not preserve the write order. Hence only set
ELEVATOR_F_ZBD_SEQ_WRITE if the LLD does not preserve the write order.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
drivers/scsi/sd_zbc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c
index a25215507668..718b31bed878 100644
--- a/drivers/scsi/sd_zbc.c
+++ b/drivers/scsi/sd_zbc.c
@@ -955,7 +955,9 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, u8 buf[SD_BUF_SIZE])

/* The drive satisfies the kernel restrictions: set it up */
blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
- blk_queue_required_elevator_features(q, ELEVATOR_F_ZBD_SEQ_WRITE);
+ if (!q->limits.driver_preserves_write_order)
+ blk_queue_required_elevator_features(q,
+ ELEVATOR_F_ZBD_SEQ_WRITE);
if (sdkp->zones_max_open == U32_MAX)
disk_set_max_open_zones(disk, 0);
else