| Message ID | 20170901113631.12323-8-damien.lemoal@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 2017-09-01 at 20:36 +0900, Damien Le Moal wrote: > In the case of a ZBC disk used with scsi-mq, zone write locking does > not prevent write reordering in sequential zones. Unlike the legacy > case, zone locking can only be done after the command request is > removed from the scheduler dispatch queue. That is, at the time of > zone locking, the write command may already be out of order. > > Disable zone write locking in sd_zbc_write_lock_zone() if the disk is > used with scsi-mq. Write order guarantees can be provided by an > adapted I/O scheduler. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c index 3a9feadcc133..0f0a74fbd9c5 100644 --- a/drivers/scsi/sd_zbc.c +++ b/drivers/scsi/sd_zbc.c @@ -258,6 +258,10 @@ int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd) (sector & (zone_sectors - 1)) + blk_rq_sectors(rq) > zone_sectors) return BLKPREP_KILL; + /* No write locking with scsi-mq */ + if (rq->q->mq_ops) + return BLKPREP_OK; + /* * There is no write constraint on conventional zones, but do not issue * more than one write at a time per sequential zone. This avoids write
In the case of a ZBC disk used with scsi-mq, zone write locking does not prevent write reordering in sequential zones. Unlike the legacy case, zone locking can only be done after the command request is removed from the scheduler dispatch queue. That is, at the time of zone locking, the write command may already be out of order. Disable zone write locking in sd_zbc_write_lock_zone() if the disk is used with scsi-mq. Write order guarantees can be provided by an adapted I/O scheduler. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- drivers/scsi/sd_zbc.c | 4 ++++ 1 file changed, 4 insertions(+)