[PATCH 8/9] nvme: implement multipath access to nvme subsystems

[Sagi Grimberg]

> +static const struct block_device_operations nvme_subsys_ops = {
> +	.owner		= THIS_MODULE,
> +};

Nit - maybe better to name this nvme_ns_head_ops

> +	ret = -ENOMEM;
> +	q = blk_alloc_queue_node(GFP_KERNEL, NUMA_NO_NODE);
> +	if (!q)
> +		goto out_free_head;
> +	q->queuedata = head;
> +	blk_queue_make_request(q, nvme_make_request);
> +	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, q);
> +	/* set to a default value for 512 until disk is validated */
> +	blk_queue_logical_block_size(q, 512);
> +	nvme_set_queue_limits(ctrl, q);
> +
> +	head->disk = alloc_disk(0);
> +	if (!head->disk)
> +		goto out_cleanup_queue;
> +	head->disk->fops = &nvme_subsys_ops;
> +	head->disk->private_data = head;
> +	head->disk->queue = q;
> +	head->disk->flags = GENHD_FL_EXT_DEVT;
> +	sprintf(head->disk->disk_name, "nvm-sub%dn%d",
> +			ctrl->subsys->instance, nsid);

Did we end up in agreement on nvmsXnY?


> @@ -2669,8 +2905,10 @@ static void nvme_ns_remove(struct nvme_ns *ns)
>   	}
>   
>   	mutex_lock(&ns->ctrl->subsys->lock);
> -	if (head)
> +	if (head) {
> +		rcu_assign_pointer(head->current_path, NULL);

Doesn't this assignment need to happen only when the ns *is* the
current_path?