On Sat, Mar 10, 2018 at 11:15:20AM +0100, Christoph Hellwig wrote:
> 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?
Client–Server.
>
> > @@ -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,
OK.
>
> > @@ -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.
>
OK.
Thanks,
Ming
