On Tue, Jun 23, 2020 at 11:25:53AM +0000, Niklas Cassel wrote:

On Tue, Jun 23, 2020 at 01:53:47AM -0700, Sagi Grimberg wrote:

quoted

quoted

  static int nvme_setup_streams_ns(struct nvme_ctrl *ctrl, struct nvme_ns *ns,

@@ -1930,6 +1950,15 @@ static int __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
  	if (ns->lba_shift == 0)
  		ns->lba_shift = 9;
+	switch (ns->head->ids.csi) {
+	case NVME_CSI_NVM:
+		break;
+	default:
+		dev_warn(ctrl->device, "unknown csi:%d ns:%d\n",
+			ns->head->ids.csi, ns->head->ns_id);
+		return -ENODEV;
+	}

Not sure we need a switch-case statement for a single case target...

I would consider it two cases. A supported CSI or a non-supported CSI
(which means any CSI value != NVME_CSI_NVM).

However, a follow up patch (patch 5/5 in this series) adds another case
to this switch-case statement (NVME_CSI_ZNS).

I guess this patch could have used an if-else statement, and patch 5/5
replaced the if-statement with a switch-case.
However, since a patch in the same series actually adds another case,
I think that it is more clear this way.
(A switch-case with only two cases added, in a patch that is not the last
one in the series, suggests (at least to me), that it will most likely be
extended in a following patch.)

Yeah, this patch is laying the foundation for future command sets.