Rbd update volume stats in wrong way

Cinder volume uses a RADOS pool to store volumes and
update storage stats periodically. However, rbd driver
reports the whole cluster stats but not the pool's. This
is wrong. The right way is to report the pool stats but
not the whole cluster.

Change-Id: Ie18324ebd8b85f7b63dc034ba20857ae9e470804
Closes-Bug: #1434441

2 files changed, 30 insertions, 13 deletions

diff --git a/cinder/tests/test_rbd.py b/cinder/tests/test_rbd.py
index b30735293..fcd3bcc63 100644
--- a/cinder/tests/test_rbd.py
+++ b/cinder/tests/test_rbd.py
@@ -662,10 +662,14 @@ class RBDTestCase(test.TestCase):
         client.__enter__.return_value = client
 
         client.cluster = mock.Mock()
-        client.cluster.get_cluster_stats = mock.Mock()
-        client.cluster.get_cluster_stats.return_value = {'kb': 1024 ** 3,
-                                                         'kb_avail': 1024 ** 2}
-
+        client.cluster.mon_command = mock.Mock()
+        client.cluster.mon_command.return_value = (
+            0, '{"stats":{"total_bytes":64385286144,'
+            '"total_used_bytes":3289628672,"total_avail_bytes":61095657472},'
+            '"pools":[{"name":"rbd","id":2,"stats":{"kb_used":1510197,'
+            '"bytes_used":1546440971,"max_avail":28987613184,"objects":412}},'
+            '{"name":"volumes","id":3,"stats":{"kb_used":0,"bytes_used":0,'
+            '"max_avail":28987613184,"objects":0}}]}\n', '')
         self.driver.configuration.safe_get = mock.Mock()
         self.driver.configuration.safe_get.return_value = 'RBD'
 
@@ -674,12 +678,13 @@ class RBDTestCase(test.TestCase):
             vendor_name='Open Source',
             driver_version=self.driver.VERSION,
             storage_protocol='ceph',
-            total_capacity_gb=1024,
-            free_capacity_gb=1,
+            total_capacity_gb=27,
+            free_capacity_gb=26,
             reserved_percentage=0)
 
         actual = self.driver.get_volume_stats(True)
-        client.cluster.get_cluster_stats.assert_called_once_with()
+        client.cluster.mon_command.assert_called_once_with(
+            '{"prefix":"df", "format":"json"}', '')
         self.assertDictMatch(expected, actual)
 
     @common_mocks
@@ -688,8 +693,8 @@ class RBDTestCase(test.TestCase):
         client.__enter__.return_value = client
 
         client.cluster = mock.Mock()
-        client.cluster.get_cluster_stats = mock.Mock()
-        client.cluster.get_cluster_stats.side_effect = Exception
+        client.cluster.mon_command = mock.Mock()
+        client.cluster.mon_command.return_value = (22, '', '')
 
         self.driver.configuration.safe_get = mock.Mock()
         self.driver.configuration.safe_get.return_value = 'RBD'
@@ -703,7 +708,8 @@ class RBDTestCase(test.TestCase):
                         reserved_percentage=0)
 
         actual = self.driver.get_volume_stats(True)
-        client.cluster.get_cluster_stats.assert_called_once_with()
+        client.cluster.mon_command.assert_called_once_with(
+            '{"prefix":"df", "format":"json"}', '')
         self.assertDictMatch(expected, actual)
 
     @common_mocks
diff --git a/cinder/volume/drivers/rbd.py b/cinder/volume/drivers/rbd.py
index d9e939b5e..7dae2ec20 100644
--- a/cinder/volume/drivers/rbd.py
+++ b/cinder/volume/drivers/rbd.py
@@ -371,9 +371,20 @@ class RBDDriver(driver.VolumeDriver):
 
         try:
             with RADOSClient(self) as client:
-                new_stats = client.cluster.get_cluster_stats()
-            stats['total_capacity_gb'] = new_stats['kb'] / units.Mi
-            stats['free_capacity_gb'] = new_stats['kb_avail'] / units.Mi
+                ret, outbuf, _outs = client.cluster.mon_command(
+                    '{"prefix":"df", "format":"json"}', '')
+                if ret != 0:
+                    LOG.warning(_LW('Unable to get rados pool stats.'))
+                else:
+                    outbuf = json.loads(outbuf)
+                    pool_stats = [pool for pool in outbuf['pools'] if
+                                  pool['name'] ==
+                                  self.configuration.rbd_pool][0]['stats']
+                    stats['free_capacity_gb'] = (
+                        pool_stats['max_avail'] / units.Gi)
+                    used_capacity_gb = pool_stats['bytes_used'] / units.Gi
+                    stats['total_capacity_gb'] = (stats['free_capacity_gb']
+                                                  + used_capacity_gb)
         except self.rados.Error:
             # just log and return unknown capacities
             LOG.exception(_LE('error refreshing volume stats'))