Validation to detect if undercloud disks use 512e

If they do use Advanced Format, the overcloud images may fail to upload
to Glance.

Change-Id: I95ad7d2a0368418620d633d0a8b556999b3db34b
Co-Authored-By: Tomas Sedovic <tsedovic@redhat.com>

validations/512e.yaml

@@ -0,0 +1,19 @@
+---
+- hosts: undercloud
+  vars:
+    metadata:
+      name: Advanced Format 512e Support
+      description: >
+        Detect whether the undercloud disks use Advanced Format. If they do,
+        the overcloud images may fail to upload to Glance.
+      groups:
+        - prep
+        - pre-deployment
+  tasks:
+  - name: List the available drives
+    register: drive_list
+    shell: "ls /sys/class/block/"
+  - name: Detect whether the drive uses Advanced Format
+    advanced_format: drive={{ item }}
+    when: '"{{ item }}" | match("^sd.$")'
+    with_items: "{{ drive_list.stdout_lines }}"

validations/library/advanced_format.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+# Copyright 2016 Red Hat, Inc.
+# All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+from os import path
+
+from ansible.module_utils.basic import *  # noqa
+
+
+def read_int(module, file_path):
+    '''Read a file and convert its value to int.
+
+    Raise ansible failure otherwise.
+    '''
+    try:
+        with open(file_path) as f:
+            file_contents = f.read()
+        return int(file_contents)
+    except IOError:
+        module.fail_json(msg="Cannot open '%s'" % file_path)
+    except ValueError:
+        module.fail_json(msg="The '%s' file doesn't contain an integer value" %
+                         file_path)
+
+
+def main():
+    module = AnsibleModule(argument_spec=dict(
+        drive=dict(required=True, type='str')
+    ))
+
+    drive = module.params.get('drive')
+    queue_path = path.join('/sys/class/block', drive, 'queue')
+
+    physical_block_size_path = path.join(queue_path, 'physical_block_size')
+    logical_block_size_path = path.join(queue_path, 'logical_block_size')
+
+    physical_block_size = read_int(module, physical_block_size_path)
+    logical_block_size = read_int(module, logical_block_size_path)
+
+    if physical_block_size == logical_block_size:
+        module.exit_json(
+            changed=False,
+            msg="The disk %s probably doesn't use Advance Format." % drive,
+        )
+    else:
+        module.exit_json(
+            # NOTE(shadower): we're marking this as `changed`, to make it
+            # visually stand out when running via Ansible directly instead of
+            # using the API.
+            #
+            # The API & UI is planned to look for the `warnings` field and
+            # display it differently.
+            changed=True,
+            warnings=["Physical and logical block sizes of drive %s differ "
+                      "(%s vs. %s). This can mean the disk uses Advance "
+                      "Format." %
+                      (drive, physical_block_size, logical_block_size)],
+        )
+
+
+if __name__ == '__main__':
+    main()