Re: [PATCH v9 01/12] nvme-core: introduce nvme_ctrl_get_by_path()

[Christoph Hellwig]

> +struct nvme_ctrl *nvme_ctrl_get_by_path(const char *path)
> +{
> +	struct nvme_ctrl *ctrl;
> +	struct file *f;
> +
> +	f = filp_open(path, O_RDWR, 0);
> +	if (IS_ERR(f))
> +		return ERR_CAST(f);
> +
> +	if (f->f_op != &nvme_dev_fops) {
> +		ctrl = ERR_PTR(-EINVAL);
> +		goto out_close;
> +	}
> +
> +	ctrl = f->private_data;
> +	nvme_get_ctrl(ctrl);
> +
> +out_close:
> +	filp_close(f, NULL);
> +
> +	return ctrl;

No need for the empty line here.  Also can you make sure this new
code (and all the new exports) are only enabled if
CONFIG_NVME_TARGET_PASSTHRU is set.  Preferably by having a little
block at the end of this file with this function and the extra
exports with a big fat comment that they are only for nvmet-passthrough.