rbd: convert bus code to use bus_groups

The bus_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the RBD bus code to use the
correct field.

Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Acked-by: NAlex Elder <elder@linaro.org>
Cc: <ceph-devel@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/block/rbd.c

@@ -397,15 +397,19 @@ static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
 static int rbd_dev_image_probe(struct rbd_device *rbd_dev, bool mapping);
 static void rbd_spec_put(struct rbd_spec *spec);
 
-static struct bus_attribute rbd_bus_attrs[] = {
-	__ATTR(add, S_IWUSR, NULL, rbd_add),
-	__ATTR(remove, S_IWUSR, NULL, rbd_remove),
-	__ATTR_NULL
+static BUS_ATTR(add, S_IWUSR, NULL, rbd_add);
+static BUS_ATTR(remove, S_IWUSR, NULL, rbd_remove);
+
+static struct attribute *rbd_bus_attrs[] = {
+	&bus_attr_add.attr,
+	&bus_attr_remove.attr,
+	NULL,
 };
+ATTRIBUTE_GROUPS(rbd_bus);
 
 static struct bus_type rbd_bus_type = {
 	.name		= "rbd",
-	.bus_attrs	= rbd_bus_attrs,
+	.bus_groups	= rbd_bus_groups,
 };
 
 static void rbd_root_dev_release(struct device *dev)