rbd: don't leak parent_spec in rbd_dev_probe_parent()

static int rbd_dev_probe_parent(struct rbd_device *rbd_dev)

{

	struct rbd_device *parent = NULL;

	struct rbd_spec *parent_spec;

	struct rbd_client *rbdc;

	int ret;

	if (!rbd_dev->parent_spec)

		return 0;

	/*

	 * We need to pass a reference to the client and the parent

	 * spec when creating the parent rbd_dev.  Images related by

	 * parent/child relationships always share both.

	 */

	parent_spec = rbd_spec_get(rbd_dev->parent_spec);

	rbdc = __rbd_get_client(rbd_dev->rbd_client);

	parent = rbd_dev_create(rbd_dev->rbd_client, rbd_dev->parent_spec,

				NULL);

	if (!parent) {

		ret = -ENOMEM;

	parent = rbd_dev_create(rbdc, parent_spec, NULL);

	if (!parent)

		goto out_err;

	}

	/*

	 * Images related by parent/child relationships always share

	 * rbd_client and spec/parent_spec, so bump their refcounts.

	 */

	__rbd_get_client(rbd_dev->rbd_client);

	rbd_spec_get(rbd_dev->parent_spec);

	ret = rbd_dev_image_probe(parent, false);

	if (ret < 0)

		goto out_err;

	rbd_dev->parent = parent;

	atomic_set(&rbd_dev->parent_ref, 1);

	return 0;

out_err:

	if (parent) {

	rbd_dev_unparent(rbd_dev);

	if (parent)

		rbd_dev_destroy(parent);

	} else {

		rbd_put_client(rbdc);

		rbd_spec_put(parent_spec);

	}

	return ret;

}