Do not use AUFS for centos/fedora/oraclelinux container images on ubuntu host

Change-Id: I9e9a96b71498a7d824d34e21028ad73f57302125
Closes-Bug: #1579583

doc/image-building.rst

@@ -188,11 +188,13 @@ image, the operator would add the following block to
 Known issues
 ============
 
-1. Can't build base image because docker fails to install systemd.
+1. Can't build base image because docker fails to install systemd or httpd.
 
    There are some issues between docker and AUFS. The simple workaround to
-   avoid the issue is that add ``-s devicemapper`` to ``DOCKER_OPTS``.  Get
-   more information about the issue from DockerBug_.
+   avoid the issue is that add ``-s devicemapper`` or ``-s btrfs`` to
+   ``DOCKER_OPTS``. Get more information about `the issue from the Docker bug
+   tracker <https://github.com/docker/docker/issues/6980>`_ and `how to
+   configure Docker with BTRFS backend <https://docs.docker.com/engine/userguide/storagedriver/btrfs-driver/#prerequisites>`_.
 
 2. Mirrors are unreliable.
 
@@ -298,5 +300,4 @@ variables that will be picked up from the user env::
 Also these variables could be overwritten using ``--build-args``, which have
 precedence.
 
-.. _DockerBug: https://github.com/docker/docker/issues/6980
 .. _drivers: https://wiki.openstack.org/wiki/Neutron#Plugins

doc/quickstart.rst

@@ -117,6 +117,9 @@ For Ubuntu 14.04 which uses upstart instead of systemd, run the following:
 
     mount --make-shared /run
 
+.. NOTE:: If centos/fedora/oraclelinux container images are built on an Ubuntu
+  host, the backend storage driver must not be AUFS (see the known issues in
+  :doc:`image-building`).
 
 On the target hosts you also need an updated version of the Docker python
 libraries: