Check the base device if the read-only file cannot be read

For some drives, the partition e.g. `/dev/sda1` will not have the
'ro' file which can result in a metadata erasure failure but the base
device (`/dev/sda`) will have this file.  Add an additional check
for the base device.

Change-Id: Ia01bdbf82cee6ce15fabdc42f9c23036df55b4c5
Story: 2008696
Task: 42004

ironic_python_agent/hardware.py

@@ -24,6 +24,7 @@ import re
 import shlex
 import shutil
 import stat
+import string
 import time
 
 from ironic_lib import disk_utils
@@ -1447,23 +1448,32 @@ class GenericHardwareManager(HardwareManager):
 
         return 'linux_raid_member' in out
 
-    def _is_read_only_device(self, block_device):
+    def _is_read_only_device(self, block_device, partition=False):
         """Check if a block device is read-only.
 
         Checks the device read-only flag in order to identify virtual
         and firmware driven devices that block write device access.
 
         :param block_device: a BlockDevice object
+        :param partition: if True, this device is a partition
         :returns: True if the device is read-only.
         """
         try:
-            dev_name = str(block_device.name)[5:]
+            dev_name = os.path.basename(block_device.name)
+            if partition:
+                # Check the base device
+                dev_name = dev_name.rstrip(string.digits)
 
             with open('/sys/block/%s/ro' % dev_name, 'r') as f:
                 flag = f.read().strip()
                 if flag == '1':
                     return True
         except IOError as e:
+            # Check underlying device as the file may exist there
+            if (not partition and dev_name[-1].isdigit()
+                and 'nvme' not in dev_name):
+                return self._is_read_only_device(block_device, partition=True)
+
             LOG.warning("Could not determine if %(name)s is a"
                         "read-only device. Error: %(err)s",
                         {'name': block_device.name, 'err': e})

ironic_python_agent/tests/unit/test_hardware.py

@@ -2184,6 +2184,26 @@ class TestGenericHardwareManager(base.IronicAgentTest):
             mock_open.assert_called_once_with(
                 '/sys/block/sdfake/ro', 'r')
 
+    def test__is_read_only_device_partition_error(self):
+        device = hardware.BlockDevice('/dev/sdfake1', 'fake', 1024, False)
+        with mock.patch(
+                'builtins.open', side_effect=IOError,
+                autospec=True) as mock_open:
+            self.assertFalse(self.hardware._is_read_only_device(device))
+            mock_open.assert_has_calls([
+                mock.call('/sys/block/sdfake1/ro', 'r'),
+                mock.call('/sys/block/sdfake/ro', 'r')])
+
+    def test__is_read_only_device_partition_ok(self):
+        fileobj = mock.mock_open(read_data='1\n')
+        device = hardware.BlockDevice('/dev/sdfake1', 'fake', 1024, False)
+        reads = [IOError, '1']
+        with mock.patch(
+                'builtins.open', fileobj, create=True) as mock_open:
+            mock_dev_file = mock_open.return_value.read
+            mock_dev_file.side_effect = reads
+            self.assertTrue(self.hardware._is_read_only_device(device))
+
     @mock.patch.object(il_utils, 'try_execute', autospec=True)
     @mock.patch.object(utils, 'execute', autospec=True)
     def test_get_bmc_address(self, mocked_execute, mte):

releasenotes/notes/partition_check_read_only_base_device-5bc15ac2f034aca9.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes an issue where metadata erasure cleaning fails for partitions
+    because the read-only file isn't found, while it is available at the
+    base device.  Adds a check for the base device file on failure. See
+    `story 2008696 <https://storyboard.openstack.org/#!/story/2008696>`_.