Re: [PATCH] nvme: remove multipath module parameter

[John Meneghini]

On 2/18/25 3:19 AM, Sagi Grimberg wrote:
> > We can send send a separate patch to address that problem, but this patch, which simply removes the nvme_core.multipath parameter
> > has beeen fully tested and is ready to go.
>
> I think that we want to print a warning in this case though. Can you resubmit with logging a warning in this case?

Agreed, but I was thinking that warning should go into the second patch. The second patch should disable all secondary paths when
CONFIG_NVME_MULTPATH=N and a namespace is discovered with NMIC enabled. Basically, we don't want to instantiate more than one
namespace when CONFIG_NVME_MULTPATH=N.

But if you want to add a warning to this patch, we could do something like this:

@@ -3909,16 +3909,23 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
                disk->flags |= GENHD_FL_HIDDEN;
        } else {
 #ifdef CONFIG_NVME_MULTIPATH
                sprintf(disk->disk_name, "nvme%dn%d", ctrl->subsys->instance,
                        ns->head->instance);
 #else
                sprintf(disk->disk_name, "nvme%dn%d", ctrl->instance,
                        ns->head->instance);
+               if (info->is_shared) {
+                       dev_warn(ctrl->device,
+                               "Found shared namespace %d but multipathing not supported.\n",
+                               info->nsid);
+                       dev_warn_one(ctrl->device,
+                               "Shared namepaces without CONFIG_NVME_MULTIPATH=Y is not supported.\n")
+               }
 #endif
        }

        if (nvme_update_ns_info(ns, info))
                goto out_unlink_ns;