nvmet: add uuid field to nvme_ns and populate via configfs

CONFIGFS_ATTR(nvmet_ns_, device_path);

static ssize_t nvmet_ns_device_uuid_show(struct config_item *item, char *page)

{

	return sprintf(page, "%pUb\n", &to_nvmet_ns(item)->uuid);

}

static ssize_t nvmet_ns_device_uuid_store(struct config_item *item,

					  const char *page, size_t count)

{

	struct nvmet_ns *ns = to_nvmet_ns(item);

	struct nvmet_subsys *subsys = ns->subsys;

	int ret = 0;

	mutex_lock(&subsys->lock);

	if (ns->enabled) {

		ret = -EBUSY;

		goto out_unlock;

	}

	if (uuid_parse(page, &ns->uuid))

		ret = -EINVAL;

out_unlock:

	mutex_unlock(&subsys->lock);

	return ret ? ret : count;

}

static ssize_t nvmet_ns_device_nguid_show(struct config_item *item, char *page)

{

	return sprintf(page, "%pUb\n", &to_nvmet_ns(item)->nguid);

}

CONFIGFS_ATTR(nvmet_ns_, device_uuid);

static ssize_t nvmet_ns_device_nguid_store(struct config_item *item,

		const char *page, size_t count)

{

static struct configfs_attribute *nvmet_ns_attrs[] = {

	&nvmet_ns_attr_device_path,

	&nvmet_ns_attr_device_nguid,

	&nvmet_ns_attr_device_uuid,

	&nvmet_ns_attr_enable,

	NULL,

};