xenapi: remove auto_disk_config check during resize

This check was introduced by the following change:
7c5c8a743c21733120c85fdefb84b4357f5848d0

This is an alternative fix to ensure resize down
is not processed if the disk cannot be resized.

Note the failure now registers an instance action
and does not leave the VM in an error state.

In addition, this keeps the behavior that a failure
to resize up and instance during spawn will not
cause the operation to fail and put the VM into error.

fixes bug 1188135
fixes bug 1187934
fixes bug 1081225

Change-Id: I5b3dfdc7fcda26c55702dde6cdf191beee0c818c

4 files changed, 52 insertions, 14 deletions

diff --git a/nova/exception.py b/nova/exception.py
index d8ad08131..68cf1f991 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -964,6 +964,10 @@ class ResizeError(NovaException):
     message = _("Resize error: %(reason)s")
 
 
+class CannotResizeDisk(NovaException):
+    message = _("Server disk was unable to be resized because: %(reason)s")
+
+
 class InstanceTypeMemoryTooSmall(NovaException):
     message = _("Instance type's memory is too small for requested image.")
 
diff --git a/nova/tests/virt/xenapi/test_xenapi.py b/nova/tests/virt/xenapi/test_xenapi.py
index 7dcb1cec8..eec900fe4 100644
--- a/nova/tests/virt/xenapi/test_xenapi.py
+++ b/nova/tests/virt/xenapi/test_xenapi.py
@@ -1297,6 +1297,7 @@ class XenAPIMigrateInstance(stubs.XenAPITestBase):
         stubs.stubout_session(self.stubs, stubs.FakeSessionForVMTests)
         db_fakes.stub_out_db_instance_api(self.stubs)
         xenapi_fake.create_network('fake', CONF.flat_network_bridge)
+        xenapi_fake.create_local_srs()
         self.user_id = 'fake'
         self.project_id = 'fake'
         self.context = context.RequestContext(self.user_id, self.project_id)
@@ -1517,16 +1518,40 @@ class XenAPIMigrateInstance(stubs.XenAPITestBase):
                               dict(base_copy='hurr', cow='durr'),
                               network_info, image_meta, resize_instance=False)
 
-    def test_migrate_no_auto_disk_config_no_resize_down(self):
-        # Resize down should fail when auto_disk_config not set.
+    @stub_vm_utils_with_vdi_attached_here
+    def test_migrate_too_many_partitions_no_resize_down(self):
         instance_values = self.instance_values
         instance_values['root_gb'] = 40
-        instance_values['auto_disk_config'] = False
         instance = db.instance_create(self.context, instance_values)
         xenapi_fake.create_vm(instance['name'], 'Running')
         instance_type = db.instance_type_get_by_name(self.context, 'm1.small')
         conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
-        self.assertRaises(exception.ResizeError,
+
+        def fake_get_partitions(partition):
+            return [(1, 2, 3, 4), (1, 2, 3, 4)]
+
+        self.stubs.Set(vm_utils, '_get_partitions', fake_get_partitions)
+
+        self.assertRaises(exception.InstanceFaultRollback,
+                          conn.migrate_disk_and_power_off,
+                          self.context, instance,
+                          '127.0.0.1', instance_type, None)
+
+    @stub_vm_utils_with_vdi_attached_here
+    def test_migrate_bad_fs_type_no_resize_down(self):
+        instance_values = self.instance_values
+        instance_values['root_gb'] = 40
+        instance = db.instance_create(self.context, instance_values)
+        xenapi_fake.create_vm(instance['name'], 'Running')
+        instance_type = db.instance_type_get_by_name(self.context, 'm1.small')
+        conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
+
+        def fake_get_partitions(partition):
+            return [(1, 2, 3, "ext2")]
+
+        self.stubs.Set(vm_utils, '_get_partitions', fake_get_partitions)
+
+        self.assertRaises(exception.InstanceFaultRollback,
                           conn.migrate_disk_and_power_off,
                           self.context, instance,
                           '127.0.0.1', instance_type, None)
diff --git a/nova/virt/xenapi/vm_utils.py b/nova/virt/xenapi/vm_utils.py
index 9c8c73ba9..943cf11cf 100644
--- a/nova/virt/xenapi/vm_utils.py
+++ b/nova/virt/xenapi/vm_utils.py
@@ -758,7 +758,7 @@ def resize_disk(session, instance, vdi_ref, instance_type):
 
     try:
         # Resize partition and filesystem down
-        auto_configure_disk(session, copy_ref, instance_type['root_gb'])
+        _auto_configure_disk(session, copy_ref, instance_type['root_gb'])
 
         # Create new VDI
         vdi_size = instance_type['root_gb'] * 1024 * 1024 * 1024
@@ -778,7 +778,7 @@ def resize_disk(session, instance, vdi_ref, instance_type):
         destroy_vdi(session, copy_ref)
 
 
-def auto_configure_disk(session, vdi_ref, new_gb):
+def _auto_configure_disk(session, vdi_ref, new_gb):
     """Partition and resize FS to match the size specified by
     flavors.root_gb.
 
@@ -798,12 +798,25 @@ def auto_configure_disk(session, vdi_ref, new_gb):
         partitions = _get_partitions(dev)
 
         if len(partitions) != 1:
-            return
+            reason = _('Disk must have only one partition.')
+            raise exception.CannotResizeDisk(reason=reason)
 
         _num, start, old_sectors, ptype = partitions[0]
         if ptype in ('ext3', 'ext4'):
             new_sectors = new_gb * 1024 * 1024 * 1024 / SECTOR_SIZE
             _resize_part_and_fs(dev, start, old_sectors, new_sectors)
+        else:
+            reason = _('Disk contains a filesystem '
+                       'we are unable to resize: %s')
+            raise exception.CannotResizeDisk(reason=(reason % ptype))
+
+
+def try_auto_configure_disk(session, vdi_ref, new_gb):
+    try:
+        _auto_configure_disk(session, vdi_ref, new_gb)
+    except exception.CannotResizeDisk as e:
+        msg = _('Attempted auto_configure_disk failed because: %s')
+        LOG.warn(msg % e)
 
 
 def _generate_disk(session, instance, vm_ref, userdevice, name_label,
diff --git a/nova/virt/xenapi/vmops.py b/nova/virt/xenapi/vmops.py
index 56a4b18d8..2d38ed547 100644
--- a/nova/virt/xenapi/vmops.py
+++ b/nova/virt/xenapi/vmops.py
@@ -592,9 +592,9 @@ class VMOps(object):
             if instance['auto_disk_config']:
                 LOG.debug(_("Auto configuring disk, attempting to "
                             "resize partition..."), instance=instance)
-                vm_utils.auto_configure_disk(self._session,
-                                             root_vdi['ref'],
-                                             instance_type['root_gb'])
+                vm_utils.try_auto_configure_disk(self._session,
+                                                 root_vdi['ref'],
+                                                 instance_type['root_gb'])
 
             vm_utils.create_vbd(self._session, vm_ref, root_vdi['ref'],
                                 DEVICE_ROOT, bootable=True,
@@ -820,10 +820,6 @@ class VMOps(object):
 
     def _migrate_disk_resizing_down(self, context, instance, dest,
                                     instance_type, vm_ref, sr_path):
-        if not instance['auto_disk_config']:
-            reason = _('Resize down not allowed without auto_disk_config')
-            raise exception.ResizeError(reason=reason)
-
         step = make_step_decorator(context, instance,
                                    self._virtapi.instance_update)