[PATCH v1 1/1] nvme: add admin controller support. prohibit ioq creation for admin & disco ctrlrs

[Keith Busch]

On Fri, Mar 28, 2025 at 02:36:40PM -0700, Kamaljit Singh wrote:
> -static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
> -{
> -	return ctrl->opts && ctrl->opts->discovery_nqn;
> -}
> -

I suppose it's fine to rename this function with an nvmf_ prefix, but
it's not really related to the rest of the patch and makes the diff
larger than necessary.

> +	/* An admin or discovery controller has one admin queue, but no I/O queues */
> +	if (nvme_admin_ctrl(&ctrl->ctrl) || nvmf_discovery_ctrl(&ctrl->ctrl)) {
> +		ctrl->ctrl.queue_count = 1;
> +	} else if (ctrl->ctrl.queue_count < 2) {
> +		/* I/O controller with no I/O queues is not allowed */
> +		ret = -EOPNOTSUPP;
> +		dev_err(ctrl->ctrl.device,
> +			"I/O controller doesn't allow zero I/O queues!\n");
> +		goto destroy_admin;
> +	}

The queue_count comes from the user. If the user provides a bad value
for an IO controller, you're erroring. If they provide a bad value for a
discovery or admin controller, you override the value. Why the different
behavior?