Catch NoValidHost exception during live-migration

To avoid leaving the instance state as MIGRATING if scheduling of
a target host fails, add this exception to the list of exceptions
for which the instance task state is reset to None.

Resolves bug 1166771.

Change-Id: I23343091725051624c0eb0b82e9f03a7f9d5f4f4

2 files changed, 34 insertions, 1 deletions

diff --git a/nova/scheduler/manager.py b/nova/scheduler/manager.py
index 3124c6af9..c6e1ed390 100644
--- a/nova/scheduler/manager.py
+++ b/nova/scheduler/manager.py
@@ -94,7 +94,8 @@ class SchedulerManager(manager.Manager):
             return self.driver.schedule_live_migration(
                 context, instance, dest,
                 block_migration, disk_over_commit)
-        except (exception.ComputeServiceUnavailable,
+        except (exception.NoValidHost,
+                exception.ComputeServiceUnavailable,
                 exception.InvalidHypervisorType,
                 exception.UnableToMigrateToSelf,
                 exception.DestinationHypervisorTooOld,
diff --git a/nova/tests/scheduler/test_scheduler.py b/nova/tests/scheduler/test_scheduler.py
index 8c8181cb1..933b4fc20 100644
--- a/nova/tests/scheduler/test_scheduler.py
+++ b/nova/tests/scheduler/test_scheduler.py
@@ -204,6 +204,38 @@ class SchedulerManagerTestCase(test.TestCase):
         self.manager.run_instance(self.context, request_spec,
                 None, None, None, None, {})
 
+    def test_live_migration_schedule_novalidhost(self):
+        inst = {"uuid": "fake-instance-id",
+                "vm_state": vm_states.ACTIVE,
+                "task_state": task_states.MIGRATING, }
+
+        dest = None
+        block_migration = False
+        disk_over_commit = False
+
+        self._mox_schedule_method_helper('schedule_live_migration')
+        self.mox.StubOutWithMock(compute_utils, 'add_instance_fault_from_exc')
+        self.mox.StubOutWithMock(db, 'instance_update_and_get_original')
+
+        self.manager.driver.schedule_live_migration(self.context,
+                    inst, dest, block_migration, disk_over_commit).AndRaise(
+                    exception.NoValidHost(reason=""))
+        db.instance_update_and_get_original(self.context, inst["uuid"],
+                                {"vm_state": inst['vm_state'],
+                                 "task_state": None,
+                                 "expected_task_state": task_states.MIGRATING,
+                                }).AndReturn((inst, inst))
+        compute_utils.add_instance_fault_from_exc(self.context,
+                                mox.IsA(conductor_api.LocalAPI), inst,
+                                mox.IsA(exception.NoValidHost),
+                                mox.IgnoreArg())
+
+        self.mox.ReplayAll()
+        self.assertRaises(exception.NoValidHost,
+                          self.manager.live_migration,
+                          self.context, inst, dest, block_migration,
+                          disk_over_commit)
+
     def test_live_migration_compute_service_notavailable(self):
         inst = {"uuid": "fake-instance-id",
                 "vm_state": vm_states.ACTIVE,