This looks generally fine to me:
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
As a follow on we should probably kill virtscsi_queuecommand_single and
thus virtscsi_host_template_single as well.
> Given storage IO is always C/S model, there isn't such issue with SCSI_MQ(blk-mq),
What does C/S mean here?
> @@ -580,10 +573,7 @@ static int virtscsi_queuecommand_single(struct Scsi_Host *sh,
> struct scsi_cmnd *sc)
> {
> struct virtio_scsi *vscsi = shost_priv(sh);
> - struct virtio_scsi_target_state *tgt =
> - scsi_target(sc->device)->hostdata;
>
> - atomic_inc(&tgt->reqs);
> return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc);
> }
> static int virtscsi_queuecommand_multi(struct Scsi_Host *sh,
> struct scsi_cmnd *sc)
> {
> struct virtio_scsi *vscsi = shost_priv(sh);
> - struct virtio_scsi_target_state *tgt =
> - scsi_target(sc->device)->hostdata;
> - struct virtio_scsi_vq *req_vq;
> -
> - if (shost_use_blk_mq(sh))
> - req_vq = virtscsi_pick_vq_mq(vscsi, sc);
> - else
> - req_vq = virtscsi_pick_vq(vscsi, tgt);
> + struct virtio_scsi_vq *req_vq = virtscsi_pick_vq_mq(vscsi, sc);
>
> return virtscsi_queuecommand(vscsi, req_vq, sc);
Given how virtscsi_pick_vq_mq works virtscsi_queuecommand_single and
virtscsi_queuecommand_multi now have identical behavior. That means
virtscsi_queuecommand_single should be removed, and
virtscsi_queuecommand_multi should be merged into virtscsi_queuecommand,
> @@ -823,6 +768,7 @@ static struct scsi_host_template virtscsi_host_template_single = {
> .target_alloc = virtscsi_target_alloc,
> .target_destroy = virtscsi_target_destroy,
> .track_queue_depth = 1,
> + .force_blk_mq = 1,
This probably isn't strictly needed. That being said with your
change we could probably just drop virtscsi_host_template_single entirely.
