check the block_device_allocate_retries

we need to check the value of the configuration item
block_device_allocate_retries in order to ensure to
retry at least once,done like that configuration
item network_allocate_retries

Change-Id: Ia5b65bd160cb4e740d21c1b51d234e14e33135e7
Closes-Bug:#1363558

nova/compute/manager.py

@@ -1203,18 +1203,28 @@ class ComputeManager(manager.Manager):
         # TODO(yamahata): creating volume simultaneously
         #                 reduces creation time?
         # TODO(yamahata): eliminate dumb polling
-        attempts = 0
         start = time.time()
-        while attempts < CONF.block_device_allocate_retries:
+        retries = CONF.block_device_allocate_retries
+        if retries < 0:
+            LOG.warn(_LW("Treating negative config value (%(retries)s) for "
+                         "'block_device_retries' as 0."),
+                     {'retries': retries})
+        # (1) treat  negative config value as 0
+        # (2) the configured value is 0, one attempt should be made
+        # (3) the configured value is > 0, then the total number attempts
+        #      is (retries + 1)
+        attempts = 1
+        if retries >= 1:
+            attempts = retries + 1
+        for attempt in range(1, attempts + 1):
             volume = self.volume_api.get(context, vol_id)
             volume_status = volume['status']
             if volume_status not in ['creating', 'downloading']:
                 if volume_status != 'available':
                     LOG.warn(_("Volume id: %s finished being created but was"
                                " not set as 'available'"), vol_id)
-                return attempts + 1
+                return attempt
             greenthread.sleep(CONF.block_device_allocate_retries_interval)
-            attempts += 1
         # NOTE(harlowja): Should only happen if we ran out of attempts
         raise exception.VolumeNotCreated(volume_id=vol_id,
                                          seconds=int(time.time() - start),

nova/tests/compute/test_compute.py

@@ -522,6 +522,36 @@ class ComputeVolumeTestCase(BaseTestCase):
         attempts = c._await_block_device_map_created(self.context, '1')
         self.assertEqual(attempts, 3)
 
+    def test_await_block_device_created_retries_negative(self):
+        c = self.compute
+        self.flags(block_device_allocate_retries=-1)
+        self.flags(block_device_allocate_retries_interval=0.1)
+
+        def volume_get(context, vol_id):
+            return {
+                'status': 'available',
+                'id': 'blah',
+            }
+
+        self.stubs.Set(c.volume_api, 'get', volume_get)
+        attempts = c._await_block_device_map_created(self.context, '1')
+        self.assertEqual(1, attempts)
+
+    def test_await_block_device_created_retries_zero(self):
+        c = self.compute
+        self.flags(block_device_allocate_retries=0)
+        self.flags(block_device_allocate_retries_interval=0.1)
+
+        def volume_get(context, vol_id):
+            return {
+                'status': 'available',
+                'id': 'blah',
+            }
+
+        self.stubs.Set(c.volume_api, 'get', volume_get)
+        attempts = c._await_block_device_map_created(self.context, '1')
+        self.assertEqual(1, attempts)
+
     def test_boot_volume_serial(self):
         with (
             mock.patch.object(objects.BlockDeviceMapping, 'save')