Update docker storage setup parameters

With the version of Docker included in CentOS 7.5 (1.13.1-63),
docker-storage-setup fails with the currently used parameters. The
error message is:

"ERROR: XFS filesystem at /var has ftype=0, cannot use overlay backend;
consider different driver or separate volume or OS reprovision"

The setup script also warns about new parameters that should be used.
This commit changes the configuration to use these new parameters.

Also increase the size of the loopback device used for testing, since
4 GB seems not to be enough anymore.

Change-Id: Ibc062aeeea6bc37df458a717c65ec917fc8e920f

roles/host-preparation/tasks/main.yml

@@ -64,8 +64,9 @@
       DEVS={{ host_preparation_docker_disk }}
       VG=docker-vg
       STORAGE_DRIVER=overlay2
-      DOCKER_ROOT_VOLUME=yes
-      DOCKER_ROOT_VOLUME_SIZE=100%FREE
+      CONTAINER_ROOT_LV_MOUNT_PATH=/var/lib/docker
+      CONTAINER_ROOT_LV_NAME=lvol1
+      CONTAINER_ROOT_LV_SIZE=100%FREE
     dest: "/etc/sysconfig/docker-storage-setup"
   when:
     - host_preparation_docker_disk is defined
@@ -87,7 +88,7 @@
         seconds: 10
 
     - name: Create file for loopback device
-      command: dd if=/dev/zero of=/tmp/loopback bs=1M count=4096
+      command: dd if=/dev/zero of=/tmp/loopback bs=1M count=8192
 
     - name: Set up loopback device
       command: losetup -f /tmp/loopback
@@ -102,8 +103,9 @@
         content: |
           VG=docker-vg
           STORAGE_DRIVER=overlay2
-          DOCKER_ROOT_VOLUME=yes
-          DOCKER_ROOT_VOLUME_SIZE=100%FREE
+          CONTAINER_ROOT_LV_MOUNT_PATH=/var/lib/docker
+          CONTAINER_ROOT_LV_NAME=lvol1
+          CONTAINER_ROOT_LV_SIZE=100%FREE
         dest: "/etc/sysconfig/docker-storage-setup"
 
 - name: Run docker-storage-setup