Adding kvm-block-migration feature.

I wrote some description the below URL. I hope it may help for reviewing.
<http://etherpad.openstack.org/kvm-block-migration>

6 files changed, 263 insertions, 207 deletions

diff --git a/nova/tests/api/openstack/test_extensions.py b/nova/tests/api/openstack/test_extensions.py
index 03aa82f3d..9a613681d 100644
--- a/nova/tests/api/openstack/test_extensions.py
+++ b/nova/tests/api/openstack/test_extensions.py
@@ -127,9 +127,7 @@ class ExtensionControllerTest(test.TestCase):
                 "updated": "2011-01-22T13:25:27-06:00",
                 "description": "The Fox In Socks Extension",
                 "alias": "FOXNSOX",
-                "links": [],
-            },
-        )
+                "links": []})
 
     def test_list_extensions_xml(self):
         app = openstack.APIRouterV11()
@@ -336,27 +334,18 @@ class ExtensionsXMLSerializerTest(test.TestCase):
 
     def test_serialize_extenstion(self):
         serializer = extensions.ExtensionsXMLSerializer()
-        data = {
-            'extension': {
-                'name': 'ext1',
-                'namespace': 'http://docs.rack.com/servers/api/ext/pie/v1.0',
-                'alias': 'RS-PIE',
-                'updated': '2011-01-22T13:25:27-06:00',
-                'description': 'Adds the capability to share an image.',
-                'links': [
-                    {
-                        'rel': 'describedby',
-                        'type': 'application/pdf',
-                        'href': 'http://docs.rack.com/servers/api/ext/cs.pdf',
-                    },
-                    {
-                        'rel': 'describedby',
-                        'type': 'application/vnd.sun.wadl+xml',
-                        'href': 'http://docs.rack.com/servers/api/ext/cs.wadl',
-                    },
-                ],
-            },
-        }
+        data = {'extension': {
+          'name': 'ext1',
+          'namespace': 'http://docs.rack.com/servers/api/ext/pie/v1.0',
+          'alias': 'RS-PIE',
+          'updated': '2011-01-22T13:25:27-06:00',
+          'description': 'Adds the capability to share an image.',
+          'links': [{'rel': 'describedby',
+                     'type': 'application/pdf',
+                     'href': 'http://docs.rack.com/servers/api/ext/cs.pdf'},
+                    {'rel': 'describedby',
+                     'type': 'application/vnd.sun.wadl+xml',
+                     'href': 'http://docs.rack.com/servers/api/ext/cs.wadl'}]}}
 
         xml = serializer.serialize(data, 'show')
         print xml
@@ -378,48 +367,30 @@ class ExtensionsXMLSerializerTest(test.TestCase):
 
     def test_serialize_extensions(self):
         serializer = extensions.ExtensionsXMLSerializer()
-        data = {
-            "extensions": [
-                {
-                    "name": "Public Image Extension",
-                    "namespace": "http://foo.com/api/ext/pie/v1.0",
-                    "alias": "RS-PIE",
-                    "updated": "2011-01-22T13:25:27-06:00",
-                    "description": "Adds the capability to share an image.",
-                    "links": [
-                        {
-                            "rel": "describedby",
+        data = {"extensions": [{
+                "name": "Public Image Extension",
+                "namespace": "http://foo.com/api/ext/pie/v1.0",
+                "alias": "RS-PIE",
+                "updated": "2011-01-22T13:25:27-06:00",
+                "description": "Adds the capability to share an image.",
+                "links": [{"rel": "describedby",
                             "type": "application/pdf",
-                            "href": "http://foo.com/api/ext/cs-pie.pdf",
-                        },
-                        {
-                            "rel": "describedby",
                             "type": "application/vnd.sun.wadl+xml",
-                            "href": "http://foo.com/api/ext/cs-pie.wadl",
-                        },
-                    ],
-                },
-                {
-                    "name": "Cloud Block Storage",
-                    "namespace": "http://foo.com/api/ext/cbs/v1.0",
-                    "alias": "RS-CBS",
-                    "updated": "2011-01-12T11:22:33-06:00",
-                    "description": "Allows mounting cloud block storage.",
-                    "links": [
-                        {
-                            "rel": "describedby",
-                            "type": "application/pdf",
-                            "href": "http://foo.com/api/ext/cs-cbs.pdf",
-                        },
-                        {
-                            "rel": "describedby",
+                            "href": "http://foo.com/api/ext/cs-pie.pdf"},
+                           {"rel": "describedby",
                             "type": "application/vnd.sun.wadl+xml",
-                            "href": "http://foo.com/api/ext/cs-cbs.wadl",
-                        },
-                    ],
-                },
-            ],
-        }
+                            "href": "http://foo.com/api/ext/cs-pie.wadl"}]},
+                {"name": "Cloud Block Storage",
+                 "namespace": "http://foo.com/api/ext/cbs/v1.0",
+                 "alias": "RS-CBS",
+                 "updated": "2011-01-12T11:22:33-06:00",
+                 "description": "Allows mounting cloud block storage.",
+                 "links": [{"rel": "describedby",
+                             "type": "application/pdf",
+                             "href": "http://foo.com/api/ext/cs-cbs.pdf"},
+                            {"rel": "describedby",
+                             "type": "application/vnd.sun.wadl+xml",
+                             "href": "http://foo.com/api/ext/cs-cbs.wadl"}]}]}
 
         xml = serializer.serialize(data, 'index')
         print xml
diff --git a/nova/tests/api/openstack/test_limits.py b/nova/tests/api/openstack/test_limits.py
index 1dc3c3a17..801b06230 100644
--- a/nova/tests/api/openstack/test_limits.py
+++ b/nova/tests/api/openstack/test_limits.py
@@ -915,86 +915,56 @@ class LimitsViewBuilderV11Test(test.TestCase):
 
     def setUp(self):
         self.view_builder = views.limits.ViewBuilderV11()
-        self.rate_limits = [
-            {
-                "URI": "*",
-                "regex": ".*",
-                "value": 10,
-                "verb": "POST",
-                "remaining": 2,
-                "unit": "MINUTE",
-                "resetTime": 1311272226,
-            },
-            {
-                "URI": "*/servers",
-                "regex": "^/servers",
-                "value": 50,
-                "verb": "POST",
-                "remaining": 10,
-                "unit": "DAY",
-                "resetTime": 1311272226,
-            },
-        ]
-        self.absolute_limits = {
-            "metadata_items": 1,
-            "injected_files": 5,
-            "injected_file_content_bytes": 5,
-        }
+        self.rate_limits = [{"URI": "*",
+                             "regex": ".*",
+                             "value": 10,
+                             "verb": "POST",
+                             "remaining": 2,
+                             "unit": "MINUTE",
+                             "resetTime": 1311272226},
+                            {"URI": "*/servers",
+                             "regex": "^/servers",
+                             "value": 50,
+                             "verb": "POST",
+                             "remaining": 10,
+                             "unit": "DAY",
+                             "resetTime": 1311272226}]
+        self.absolute_limits = {"metadata_items": 1,
+                                "injected_files": 5,
+                                "injected_file_content_bytes": 5}
 
     def tearDown(self):
         pass
 
     def test_build_limits(self):
-        expected_limits = {
-            "limits": {
-                "rate": [
-                    {
-                        "uri": "*",
-                        "regex": ".*",
-                        "limit": [
-                            {
-                                "value": 10,
-                                "verb": "POST",
-                                "remaining": 2,
-                                "unit": "MINUTE",
-                                "next-available": "2011-07-21T18:17:06Z",
-                            },
-                        ]
-                    },
-                    {
-                        "uri": "*/servers",
-                        "regex": "^/servers",
-                        "limit": [
-                            {
-                                "value": 50,
-                                "verb": "POST",
-                                "remaining": 10,
-                                "unit": "DAY",
-                                "next-available": "2011-07-21T18:17:06Z",
-                            },
-                        ]
-                    },
-                ],
-                "absolute": {
-                    "maxServerMeta": 1,
-                    "maxImageMeta": 1,
-                    "maxPersonality": 5,
-                    "maxPersonalitySize": 5
-                }
-            }
-        }
+        expected_limits = {"limits": {
+                "rate": [{
+                      "uri": "*",
+                      "regex": ".*",
+                      "limit": [{"value": 10,
+                                 "verb": "POST",
+                                 "remaining": 2,
+                                 "unit": "MINUTE",
+                                 "next-available": "2011-07-21T18:17:06Z"}]},
+                   {"uri": "*/servers",
+                    "regex": "^/servers",
+                    "limit": [{"value": 50,
+                               "verb": "POST",
+                               "remaining": 10,
+                               "unit": "DAY",
+                               "next-available": "2011-07-21T18:17:06Z"}]}],
+                "absolute": {"maxServerMeta": 1,
+                             "maxImageMeta": 1,
+                             "maxPersonality": 5,
+                             "maxPersonalitySize": 5}}}
 
         output = self.view_builder.build(self.rate_limits,
                                          self.absolute_limits)
         self.assertDictMatch(output, expected_limits)
 
     def test_build_limits_empty_limits(self):
-        expected_limits = {
-            "limits": {
-                "rate": [],
-                "absolute": {},
-            }
-        }
+        expected_limits = {"limits": {"rate": [],
+                           "absolute": {}}}
 
         abs_limits = {}
         rate_limits = []
@@ -1012,45 +982,28 @@ class LimitsXMLSerializationTest(test.TestCase):
 
     def test_index(self):
         serializer = limits.LimitsXMLSerializer()
-
-        fixture = {
-            "limits": {
-                "rate": [
-                    {
-                        "uri": "*",
-                        "regex": ".*",
-                        "limit": [
-                            {
-                                "value": 10,
-                                "verb": "POST",
-                                "remaining": 2,
-                                "unit": "MINUTE",
-                                "next-available": "2011-12-15T22:42:45Z",
-                            },
-                        ]
-                    },
-                    {
-                        "uri": "*/servers",
-                        "regex": "^/servers",
-                        "limit": [
-                            {
-                                "value": 50,
-                                "verb": "POST",
-                                "remaining": 10,
-                                "unit": "DAY",
-                                "next-available": "2011-12-15T22:42:45Z"
-                            },
-                        ]
-                    },
-                ],
-                "absolute": {
-                    "maxServerMeta": 1,
-                    "maxImageMeta": 1,
-                    "maxPersonality": 5,
-                    "maxPersonalitySize": 10240
-                }
-            }
-        }
+        fixture = {"limits": {
+                   "rate": [{
+                         "uri": "*",
+                         "regex": ".*",
+                         "limit": [{
+                              "value": 10,
+                              "verb": "POST",
+                              "remaining": 2,
+                              "unit": "MINUTE",
+                              "next-available": "2011-12-15T22:42:45Z"}]},
+                          {"uri": "*/servers",
+                           "regex": "^/servers",
+                           "limit": [{
+                              "value": 50,
+                              "verb": "POST",
+                              "remaining": 10,
+                              "unit": "DAY",
+                              "next-available": "2011-12-15T22:42:45Z"}]}],
+                    "absolute": {"maxServerMeta": 1,
+                                 "maxImageMeta": 1,
+                                 "maxPersonality": 5,
+                                 "maxPersonalitySize": 10240}}}
 
         output = serializer.serialize(fixture, 'index')
         actual = minidom.parseString(output.replace("  ", ""))
@@ -1083,12 +1036,9 @@ class LimitsXMLSerializationTest(test.TestCase):
     def test_index_no_limits(self):
         serializer = limits.LimitsXMLSerializer()
 
-        fixture = {
-            "limits": {
-                "rate": [],
-                "absolute": {},
-            }
-        }
+        fixture = {"limits": {
+                   "rate": [],
+                   "absolute": {}}}
 
         output = serializer.serialize(fixture, 'index')
         actual = minidom.parseString(output.replace("  ", ""))
diff --git a/nova/tests/api/openstack/test_servers.py b/nova/tests/api/openstack/test_servers.py
index 1a4288ae7..a510d7d97 100644
--- a/nova/tests/api/openstack/test_servers.py
+++ b/nova/tests/api/openstack/test_servers.py
@@ -3056,8 +3056,7 @@ class ServersViewBuilderV11Test(test.TestCase):
             address_builder,
             flavor_builder,
             image_builder,
-            base_url,
-            )
+            base_url)
         return view_builder
 
     def test_build_server(self):
diff --git a/nova/tests/scheduler/test_scheduler.py b/nova/tests/scheduler/test_scheduler.py
index d70a6779f..33461025f 100644
--- a/nova/tests/scheduler/test_scheduler.py
+++ b/nova/tests/scheduler/test_scheduler.py
@@ -644,10 +644,13 @@ class SimpleDriverTestCase(test.TestCase):
         self.mox.StubOutWithMock(driver_i, '_live_migration_dest_check')
         self.mox.StubOutWithMock(driver_i, '_live_migration_common_check')
         driver_i._live_migration_src_check(nocare, nocare)
-        driver_i._live_migration_dest_check(nocare, nocare, i_ref['host'])
-        driver_i._live_migration_common_check(nocare, nocare, i_ref['host'])
+        driver_i._live_migration_dest_check(nocare, nocare,
+                                            i_ref['host'], False)
+        driver_i._live_migration_common_check(nocare, nocare,
+                                              i_ref['host'], False)
         self.mox.StubOutWithMock(rpc, 'cast', use_mock_anything=True)
-        kwargs = {'instance_id': instance_id, 'dest': i_ref['host']}
+        kwargs = {'instance_id': instance_id, 'dest': i_ref['host'],
+                  'block_migration': False}
         rpc.cast(self.context,
                  db.queue_get_for(nocare, FLAGS.compute_topic, i_ref['host']),
                  {"method": 'live_migration', "args": kwargs})
@@ -655,7 +658,8 @@ class SimpleDriverTestCase(test.TestCase):
         self.mox.ReplayAll()
         self.scheduler.live_migration(self.context, FLAGS.compute_topic,
                                       instance_id=instance_id,
-                                      dest=i_ref['host'])
+                                      dest=i_ref['host'],
+                                      block_migration=False)
 
         i_ref = db.instance_get(self.context, instance_id)
         self.assertTrue(i_ref['state_description'] == 'migrating')
@@ -736,7 +740,7 @@ class SimpleDriverTestCase(test.TestCase):
 
         self.assertRaises(exception.ComputeServiceUnavailable,
                           self.scheduler.driver._live_migration_dest_check,
-                          self.context, i_ref, i_ref['host'])
+                          self.context, i_ref, i_ref['host'], False)
 
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -749,7 +753,7 @@ class SimpleDriverTestCase(test.TestCase):
 
         self.assertRaises(exception.UnableToMigrateToSelf,
                           self.scheduler.driver._live_migration_dest_check,
-                          self.context, i_ref, i_ref['host'])
+                          self.context, i_ref, i_ref['host'], False)
 
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -757,15 +761,33 @@ class SimpleDriverTestCase(test.TestCase):
     def test_live_migration_dest_check_service_lack_memory(self):
         """Confirms exception raises when dest doesn't have enough memory."""
         instance_id = self._create_instance()
+        instance_id2 = self._create_instance(host='somewhere',
+                                             memory_mb=12)
         i_ref = db.instance_get(self.context, instance_id)
-        s_ref = self._create_compute_service(host='somewhere',
-                                             memory_mb_used=12)
+        s_ref = self._create_compute_service(host='somewhere')
+
+        self.assertRaises(exception.MigrationError,
+                          self.scheduler.driver._live_migration_dest_check,
+                          self.context, i_ref, 'somewhere', False)
+
+        db.instance_destroy(self.context, instance_id)
+        db.instance_destroy(self.context, instance_id2)
+        db.service_destroy(self.context, s_ref['id'])
+
+    def test_block_migration_dest_check_service_lack_disk(self):
+        """Confirms exception raises when dest doesn't have enough disk."""
+        instance_id = self._create_instance()
+        instance_id2 = self._create_instance(host='somewhere',
+                                             local_gb=70)
+        i_ref = db.instance_get(self.context, instance_id)
+        s_ref = self._create_compute_service(host='somewhere')
 
         self.assertRaises(exception.MigrationError,
                           self.scheduler.driver._live_migration_dest_check,
-                          self.context, i_ref, 'somewhere')
+                          self.context, i_ref, 'somewhere', True)
 
         db.instance_destroy(self.context, instance_id)
+        db.instance_destroy(self.context, instance_id2)
         db.service_destroy(self.context, s_ref['id'])
 
     def test_live_migration_dest_check_service_works_correctly(self):
@@ -777,7 +799,8 @@ class SimpleDriverTestCase(test.TestCase):
 
         ret = self.scheduler.driver._live_migration_dest_check(self.context,
                                                              i_ref,
-                                                             'somewhere')
+                                                             'somewhere',
+                                                             False)
         self.assertTrue(ret is None)
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -810,9 +833,10 @@ class SimpleDriverTestCase(test.TestCase):
              "args": {'filename': fpath}})
 
         self.mox.ReplayAll()
-        self.assertRaises(exception.SourceHostUnavailable,
+        #self.assertRaises(exception.SourceHostUnavailable,
+        self.assertRaises(exception.FileNotFound,
                           self.scheduler.driver._live_migration_common_check,
-                          self.context, i_ref, dest)
+                          self.context, i_ref, dest, False)
 
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -836,7 +860,7 @@ class SimpleDriverTestCase(test.TestCase):
         self.mox.ReplayAll()
         self.assertRaises(exception.InvalidHypervisorType,
                           self.scheduler.driver._live_migration_common_check,
-                          self.context, i_ref, dest)
+                          self.context, i_ref, dest, False)
 
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -862,7 +886,7 @@ class SimpleDriverTestCase(test.TestCase):
         self.mox.ReplayAll()
         self.assertRaises(exception.DestinationHypervisorTooOld,
                           self.scheduler.driver._live_migration_common_check,
-                          self.context, i_ref, dest)
+                          self.context, i_ref, dest, False)
 
         db.instance_destroy(self.context, instance_id)
         db.service_destroy(self.context, s_ref['id'])
@@ -894,7 +918,8 @@ class SimpleDriverTestCase(test.TestCase):
         try:
             self.scheduler.driver._live_migration_common_check(self.context,
                                                                i_ref,
-                                                               dest)
+                                                               dest,
+                                                               False)
         except rpc.RemoteError, e:
             c = (e.message.find(_("doesn't have compatibility to")) >= 0)
 
diff --git a/nova/tests/test_compute.py b/nova/tests/test_compute.py
index 9d6e5aee5..e2fa3b140 100644
--- a/nova/tests/test_compute.py
+++ b/nova/tests/test_compute.py
@@ -714,11 +714,15 @@ class ComputeTestCase(test.TestCase):
         dbmock.queue_get_for(c, FLAGS.compute_topic, i_ref['host']).\
                              AndReturn(topic)
         rpc.call(c, topic, {"method": "pre_live_migration",
-                            "args": {'instance_id': i_ref['id']}})
+                            "args": {'instance_id': i_ref['id'],
+                                     'block_migration': False,
+                                     'disk': None}})
+
         self.mox.StubOutWithMock(self.compute.driver, 'live_migration')
         self.compute.driver.live_migration(c, i_ref, i_ref['host'],
                                   self.compute.post_live_migration,
-                                  self.compute.recover_live_migration)
+                                  self.compute.rollback_live_migration,
+                                  False)
 
         self.compute.db = dbmock
         self.mox.ReplayAll()
@@ -739,13 +743,18 @@ class ComputeTestCase(test.TestCase):
         dbmock.queue_get_for(c, FLAGS.compute_topic, i_ref['host']).\
                              AndReturn(topic)
         rpc.call(c, topic, {"method": "pre_live_migration",
-                            "args": {'instance_id': i_ref['id']}}).\
+                            "args": {'instance_id': i_ref['id'],
+                                     'block_migration': False,
+                                     'disk': None}}).\
                             AndRaise(rpc.RemoteError('', '', ''))
         dbmock.instance_update(c, i_ref['id'], {'state_description': 'running',
                                                 'state': power_state.RUNNING,
                                                 'host': i_ref['host']})
         for v in i_ref['volumes']:
             dbmock.volume_update(c, v['id'], {'status': 'in-use'})
+            # mock for volume_api.remove_from_compute
+            rpc.call(c, topic, {"method": "remove_volume",
+                                "args": {'volume_id': v['id']}})
 
         self.compute.db = dbmock
         self.mox.ReplayAll()
@@ -766,7 +775,9 @@ class ComputeTestCase(test.TestCase):
                              AndReturn(topic)
         self.mox.StubOutWithMock(rpc, 'call')
         rpc.call(c, topic, {"method": "pre_live_migration",
-                            "args": {'instance_id': i_ref['id']}}).\
+                            "args": {'instance_id': i_ref['id'],
+                                     'block_migration': False,
+                                     'disk': None}}).\
                             AndRaise(rpc.RemoteError('', '', ''))
         dbmock.instance_update(c, i_ref['id'], {'state_description': 'running',
                                                 'state': power_state.RUNNING,
@@ -791,11 +802,14 @@ class ComputeTestCase(test.TestCase):
         dbmock.queue_get_for(c, FLAGS.compute_topic, i_ref['host']).\
                              AndReturn(topic)
         rpc.call(c, topic, {"method": "pre_live_migration",
-                            "args": {'instance_id': i_ref['id']}})
+                            "args": {'instance_id': i_ref['id'],
+                                     'block_migration': False,
+                                     'disk': None}})
         self.mox.StubOutWithMock(self.compute.driver, 'live_migration')
         self.compute.driver.live_migration(c, i_ref, i_ref['host'],
                                   self.compute.post_live_migration,
-                                  self.compute.recover_live_migration)
+                                  self.compute.rollback_live_migration,
+                                  False)
 
         self.compute.db = dbmock
         self.mox.ReplayAll()
@@ -829,6 +843,10 @@ class ComputeTestCase(test.TestCase):
             self.compute.volume_manager.remove_compute_volume(c, v['id'])
         self.mox.StubOutWithMock(self.compute.driver, 'unfilter_instance')
         self.compute.driver.unfilter_instance(i_ref, [])
+        self.mox.StubOutWithMock(rpc, 'call')
+        rpc.call(c, db.queue_get_for(c, FLAGS.compute_topic, dest),
+            {"method": "post_live_migration_at_destination",
+             "args": {'instance_id': i_ref['id'], 'block_migration': False}})
 
         # executing
         self.mox.ReplayAll()
diff --git a/nova/tests/test_libvirt.py b/nova/tests/test_libvirt.py
index 97f6aaec3..688518bb8 100644
--- a/nova/tests/test_libvirt.py
+++ b/nova/tests/test_libvirt.py
@@ -21,6 +21,7 @@ import os
 import re
 import shutil
 import sys
+import tempfile
 
 from xml.etree.ElementTree import fromstring as xml_to_tree
 from xml.dom.minidom import parseString as xml_to_dom
@@ -696,17 +697,20 @@ class LibvirtConnTestCase(test.TestCase):
                 return vdmock
 
         self.create_fake_libvirt_mock(lookupByName=fake_lookup)
-        self.mox.StubOutWithMock(self.compute, "recover_live_migration")
-        self.compute.recover_live_migration(self.context, instance_ref,
-                                            dest='dest')
-
-        # Start test
+#        self.mox.StubOutWithMock(self.compute, "recover_live_migration")
+        self.mox.StubOutWithMock(self.compute, "rollback_live_migration")
+#        self.compute.recover_live_migration(self.context, instance_ref,
+#                                             dest='dest')
+        self.compute.rollback_live_migration(self.context, instance_ref,
+                                            'dest', False)
+
+        #start test
         self.mox.ReplayAll()
         conn = connection.LibvirtConnection(False)
         self.assertRaises(libvirt.libvirtError,
                       conn._live_migration,
-                      self.context, instance_ref, 'dest', '',
-                      self.compute.recover_live_migration)
+                      self.context, instance_ref, 'dest', False,
+                      self.compute.rollback_live_migration)
 
         instance_ref = db.instance_get(self.context, instance_ref['id'])
         self.assertTrue(instance_ref['state_description'] == 'running')
@@ -717,6 +721,95 @@ class LibvirtConnTestCase(test.TestCase):
         db.volume_destroy(self.context, volume_ref['id'])
         db.instance_destroy(self.context, instance_ref['id'])
 
+    def test_pre_block_migration_works_correctly(self):
+        """Confirms pre_block_migration works correctly."""
+
+        # Skip if non-libvirt environment
+        if not self.lazy_load_library_exists():
+            return
+
+        # Replace instances_path since this testcase creates tmpfile
+        tmpdir = tempfile.mkdtemp()
+        store = FLAGS.instances_path
+        FLAGS.instances_path = tmpdir
+
+        # Test data
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyjson = '[{"path": "%s/disk", "local_gb": "10G", "type": "raw"}]'
+
+        # Preparing mocks
+        # qemu-img should be mockd since test environment might not have
+        # large disk space.
+        self.mox.StubOutWithMock(utils, "execute")
+        utils.execute('sudo', 'qemu-img', 'create', '-f', 'raw',
+                      '%s/%s/disk' % (tmpdir, instance_ref.name), '10G')
+
+        self.mox.ReplayAll()
+        conn = connection.LibvirtConnection(False)
+        conn.pre_block_migration(self.context, instance_ref,
+                                 dummyjson % tmpdir)
+
+        self.assertTrue(os.path.exists('%s/%s/' %
+                                       (tmpdir, instance_ref.name)))
+
+        shutil.rmtree(tmpdir)
+        db.instance_destroy(self.context, instance_ref['id'])
+        # Restore FLAGS.instances_path
+        FLAGS.instances_path = store
+
+    def test_get_instance_disk_info_works_correctly(self):
+        """Confirms pre_block_migration works correctly."""
+        # Skip if non-libvirt environment
+        if not self.lazy_load_library_exists():
+            return
+
+        # Test data
+        instance_ref = db.instance_create(self.context, self.test_instance)
+        dummyxml = ("<domain type='kvm'><name>instance-0000000a</name>"
+                    "<devices>"
+                    "<disk type='file'><driver name='qemu' type='raw'/>"
+                    "<source file='/test/disk'/>"
+                    "<target dev='vda' bus='virtio'/></disk>"
+                    "<disk type='file'><driver name='qemu' type='qcow2'/>"
+                    "<source file='/test/disk.local'/>"
+                    "<target dev='vdb' bus='virtio'/></disk>"
+                    "</devices></domain>")
+
+        ret = ("image: /test/disk\nfile format: raw\n"
+               "virtual size: 20G (21474836480 bytes)\ndisk size: 3.1G\n")
+
+        # Preparing mocks
+        vdmock = self.mox.CreateMock(libvirt.virDomain)
+        self.mox.StubOutWithMock(vdmock, "XMLDesc")
+        vdmock.XMLDesc(0).AndReturn(dummyxml)
+
+        def fake_lookup(instance_name):
+            if instance_name == instance_ref.name:
+                return vdmock
+        self.create_fake_libvirt_mock(lookupByName=fake_lookup)
+
+        self.mox.StubOutWithMock(os.path, "getsize")
+        # based on above testdata, one is raw image, so getsize is mocked.
+        os.path.getsize("/test/disk").AndReturn(10 * 1024 * 1024 * 1024)
+        # another is qcow image, so qemu-img should be mocked.
+        self.mox.StubOutWithMock(utils, "execute")
+        utils.execute('sudo', 'qemu-img', 'info', '/test/disk.local').\
+            AndReturn((ret, ''))
+
+        self.mox.ReplayAll()
+        conn = connection.LibvirtConnection(False)
+        info = conn.get_instance_disk_info(self.context, instance_ref)
+        info = utils.loads(info)
+
+        self.assertTrue(info[0]['type'] == 'raw' and
+                        info[1]['type'] == 'qcow2' and
+                        info[0]['path'] == '/test/disk' and
+                        info[1]['path'] == '/test/disk.local' and
+                        info[0]['local_gb'] == '10G' and
+                        info[1]['local_gb'] == '20G')
+
+        db.instance_destroy(self.context, instance_ref['id'])
+
     def test_spawn_with_network_info(self):
         # Skip if non-libvirt environment
         if not self.lazy_load_library_exists():