better syntax

roles/ceph-rbd/tasks/main.yml

@@ -26,10 +26,10 @@
 
 - name: create rbd image
   when:
-    - ceph_check_image.changed
+    - ceph_check_image is changed
     - inventory_hostname == play_hosts[0]
   command:
-    cmd: rbd -n client.{{ ceph_login }} create {{ ceph_pool_name }}/{{ ceph_image_name }} {% for param in ceph_parameters %}{{ param }} {% endfor %}
+    cmd: rbd -n client.{{ ceph_login }} create {{ ceph_pool_name }}/{{ ceph_image_name }} {{ ceph_parameters | join(' ') }}
 
 - name: map rbd image to device
   command: