Recache or rebuild missing images on hard_reboot

The primary purpose of this change is to provide the ability to
re-cache missing backing files on hard_reboot. The old
pre_block_migration function was already performing a very similar
operation. That function has been refactored to be idempotent and
renamed to _create_images_and_backing. The pre_block_migration
function is a wrapper, with some additional checking, around the
renamed function.

Image backend was also adjusted to look for either a missing backing
file or disk image, recaching or creating accordingly. It should
also be idempotent, never clobbering existing images.

Change-Id: Icf4c488d6db59e732b463d08d0606b428ee1e7b9

nova/tests/test_hypervapi.py

@@ -486,7 +486,8 @@ class HyperVAPITestCase(test.TestCase):
                                      constants.HYPERV_VM_STATE_REBOOT)
 
         self._mox.ReplayAll()
-        self._conn.reboot(self._instance_data, network_info, None)
+        self._conn.reboot(self._context, self._instance_data, network_info,
+                          None)
         self._mox.VerifyAll()
 
     def test_destroy(self):

nova/tests/test_imagebackend.py

@@ -55,8 +55,8 @@ class _ImageTestCase(object):
 
     def test_cache(self):
         self.mox.StubOutWithMock(os.path, 'exists')
-        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_DIR).AndReturn(False)
+        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_PATH).AndReturn(False)
         fn = self.mox.CreateMockAnything()
         fn(target=self.TEMPLATE_PATH)
@@ -72,7 +72,9 @@ class _ImageTestCase(object):
 
     def test_cache_image_exists(self):
         self.mox.StubOutWithMock(os.path, 'exists')
+        os.path.exists(self.TEMPLATE_DIR).AndReturn(True)
         os.path.exists(self.PATH).AndReturn(True)
+        os.path.exists(self.TEMPLATE_PATH).AndReturn(True)
         self.mox.ReplayAll()
 
         image = self.image_class(self.INSTANCE, self.NAME)
@@ -82,8 +84,8 @@ class _ImageTestCase(object):
 
     def test_cache_base_dir_exists(self):
         self.mox.StubOutWithMock(os.path, 'exists')
-        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_DIR).AndReturn(True)
+        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_PATH).AndReturn(False)
         fn = self.mox.CreateMockAnything()
         fn(target=self.TEMPLATE_PATH)
@@ -98,8 +100,8 @@ class _ImageTestCase(object):
 
     def test_cache_template_exists(self):
         self.mox.StubOutWithMock(os.path, 'exists')
-        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_DIR).AndReturn(True)
+        os.path.exists(self.PATH).AndReturn(False)
         os.path.exists(self.TEMPLATE_PATH).AndReturn(True)
         fn = self.mox.CreateMockAnything()
         self.mox.ReplayAll()
@@ -195,7 +197,6 @@ class Qcow2TestCase(_ImageTestCase, test.TestCase):
     def test_create_image_with_size(self):
         fn = self.prepare_mocks()
         fn(target=self.TEMPLATE_PATH)
-        self.mox.StubOutWithMock(os.path, 'exists')
         imagebackend.libvirt_utils.create_cow_image(self.TEMPLATE_PATH,
                                                     self.PATH)
         imagebackend.disk.extend(self.PATH, self.SIZE)

nova/tests/test_libvirt.py

@@ -4206,7 +4206,7 @@ class LibvirtDriverTestCase(test.TestCase):
 
         self.counter = 0
 
-        def fake_get_instance_disk_info(instance):
+        def fake_get_instance_disk_info(instance, xml=None):
             return '[]'
 
         def fake_destroy(instance):
@@ -4251,7 +4251,7 @@ class LibvirtDriverTestCase(test.TestCase):
                       'disk_size':'83886080'}]
         disk_info_text = jsonutils.dumps(disk_info)
 
-        def fake_get_instance_disk_info(instance):
+        def fake_get_instance_disk_info(instance, xml=None):
             return disk_info_text
 
         def fake_destroy(instance):

nova/tests/test_virt_drivers.py

@@ -104,6 +104,13 @@ class _FakeDriverBackendTestCase(object):
         def fake_make_drive(_self, _path):
             pass
 
+        def fake_get_instance_disk_info(_self, instance, xml=None):
+            return '[]'
+
+        self.stubs.Set(nova.virt.libvirt.driver.LibvirtDriver,
+                       'get_instance_disk_info',
+                       fake_get_instance_disk_info)
+
         self.stubs.Set(nova.virt.libvirt.driver.disk,
                        'extend', fake_extend)
 
@@ -227,7 +234,8 @@ class _VirtDriverTestCase(_FakeDriverBackendTestCase):
     def test_reboot(self):
         reboot_type = "SOFT"
         instance_ref, network_info = self._get_running_instance()
-        self.connection.reboot(instance_ref, network_info, reboot_type)
+        self.connection.reboot(self.ctxt, instance_ref, network_info,
+                               reboot_type)
 
     @catch_notimplementederror
     def test_get_host_ip_addr(self):

nova/tests/test_vmwareapi.py

@@ -199,14 +199,16 @@ class VMwareAPIVMTestCase(test.TestCase):
         info = self.conn.get_info({'name': 1})
         self._check_vm_info(info, power_state.RUNNING)
         reboot_type = "SOFT"
-        self.conn.reboot(self.instance, self.network_info, reboot_type)
+        self.conn.reboot(self.context, self.instance, self.network_info,
+                         reboot_type)
         info = self.conn.get_info({'name': 1})
         self._check_vm_info(info, power_state.RUNNING)
 
     def test_reboot_non_existent(self):
         self._create_instance_in_the_db()
         self.assertRaises(exception.InstanceNotFound, self.conn.reboot,
-                          self.instance, self.network_info, 'SOFT')
+                          self.context, self.instance, self.network_info,
+                          'SOFT')
 
     def test_reboot_not_poweredon(self):
         self._create_vm()
@@ -216,7 +218,8 @@ class VMwareAPIVMTestCase(test.TestCase):
         info = self.conn.get_info({'name': 1})
         self._check_vm_info(info, power_state.SUSPENDED)
         self.assertRaises(exception.InstanceRebootFailure, self.conn.reboot,
-                          self.instance, self.network_info, 'SOFT')
+                          self.context, self.instance, self.network_info,
+                          'SOFT')
 
     def test_suspend(self):
         self._create_vm()

nova/tests/test_xenapi.py

@@ -954,12 +954,12 @@ class XenAPIVMTestCase(stubs.XenAPITestBase):
     def test_reboot_hard(self):
         instance = self._create_instance()
         conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
-        conn.reboot(instance, None, "HARD")
+        conn.reboot(self.context, instance, None, "HARD")
 
     def test_reboot_soft(self):
         instance = self._create_instance()
         conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
-        conn.reboot(instance, None, "SOFT")
+        conn.reboot(self.context, instance, None, "SOFT")
 
     def test_reboot_halted(self):
         session = xenapi_conn.XenAPISession('test_url', 'root', 'test_pass',
@@ -967,7 +967,7 @@ class XenAPIVMTestCase(stubs.XenAPITestBase):
         instance = self._create_instance(spawn=False)
         conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
         xenapi_fake.create_vm(instance['name'], 'Halted')
-        conn.reboot(instance, None, "SOFT")
+        conn.reboot(self.context, instance, None, "SOFT")
         vm_ref = vm_utils.lookup(session, instance['name'])
         vm = xenapi_fake.get_record('VM', vm_ref)
         self.assertEquals(vm['power_state'], 'Running')
@@ -976,8 +976,8 @@ class XenAPIVMTestCase(stubs.XenAPITestBase):
         instance = self._create_instance(spawn=False)
         conn = xenapi_conn.XenAPIDriver(fake.FakeVirtAPI(), False)
         xenapi_fake.create_vm(instance['name'], 'Unknown')
-        self.assertRaises(xenapi_fake.Failure, conn.reboot, instance,
-                None, "SOFT")
+        self.assertRaises(xenapi_fake.Failure, conn.reboot, self.context,
+                          instance, None, "SOFT")
 
     def _test_maintenance_mode(self, find_host, find_aggregate):
         real_call_xenapi = self.conn._session.call_xenapi