[PATCHv3 3/5] nvme: implement I/O Command Sets Command Set support

[Sagi Grimberg]

>>> And what if it is a DNR error? For example, the controller simply
>>> doesn't support this CNS value. While the controller should support it,
>>> we definitely don't need it for NVM command set namespaces.
>>
>> Maybe I mis-undersatnd the comment, but if you see a DNR error, it means
>> that the controller replied an error and its final, so then you can have
>> extra checks.
> 
> If the controller does not support the CNS value, it may return Invalid
> Field with DNR set. That error currently gets propogated back to
> nvme_init_ns_head(), which then abandons the namespace. Just as the code
> coments say, we had been historically been clearing such errors because
> we have other ways to identify the namespace, but now we're not clearing
> that error.

I don't understand what you are saying Keith.

My comment was for this block:
--
	if (!status && nvme_multi_css(ctrl) && !csi_seen) {
		dev_warn(ctrl->device, "Command set not reported for nsid:%d\n",
			 nsid);
		status = -EINVAL;
	}
--

I was saying that !status doesn't necessarily mean success, but it can
also mean that its an retry-able error status (due to transport or
controller). If we see a retry-able error we should still clear the
status so we don't abandon the namespace.

This for example would achieve that:
--
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index ba512c45b40f..46d8a8379aff 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1126,12 +1126,21 @@ static int nvme_identify_ns_descs(struct 
nvme_ctrl *ctrl, unsigned nsid,
         if (status) {
                 dev_warn(ctrl->device,
                         "Identify Descriptors failed (%d)\n", status);
-                /*
-                 * Don't treat an error as fatal, as we potentially already
-                 * have a NGUID or EUI-64.
-                 */
-               if (status > 0 && !(status & NVME_SC_DNR))
-                       status = 0;
+
+               if (status > 0 && !(status & NVME_SC_DNR)) {
+                       if (nvme_multi_css(ctrl) && !csi_seen) {
+                               dev_warn(ctrl->device,
+                                       "Command set not reported for 
nsid:%d\n",
+                                       nsid);
+                               status = -EINVAL;
+                       } else {
+                               /*
+                                * Don't treat an error as fatal, as we
+                                * potentially already have a NGUID or 
EUI-64.
+                                */
+                               status = 0;
+                       }
+               }
                 goto free_data;
         }
--