Dell EMC PS: Report total volumes on the backend

Adds support to report total_volumes in the volume stats. Total number
of volumes on the storage backend can be used in custom driver
filter functions.

Change-Id: I4dcbfada009efa4157558967dce3272c641ed324
Implements: blueprint ps-report-total-volumes
Closes-Bug: #1714338

cinder/tests/unit/volume/drivers/dell_emc/test_ps.py

@@ -58,7 +58,8 @@ class PSSeriesISCSIDriverTestCase(test.TestCase):
 
         self.driver_stats_output = ['TotalCapacity: 111GB',
                                     'FreeSpace: 11GB',
-                                    'VolumeReserve: 80GB']
+                                    'VolumeReserve: 80GB',
+                                    'TotalVolumes: 100']
         self.cmd = 'this is dummy command'
         self._context = context.get_admin_context()
         self.driver = ps.PSSeriesISCSIDriver(
@@ -410,6 +411,7 @@ class PSSeriesISCSIDriverTestCase(test.TestCase):
             thin_enabled = self.configuration.san_thin_provision
             self.assertEqual(float('111.0'), stats['total_capacity_gb'])
             self.assertEqual(float('11.0'), stats['free_capacity_gb'])
+            self.assertEqual(100, stats['total_volumes'])
 
             if thin_enabled:
                 self.assertEqual(80.0, stats['provisioned_capacity_gb'])

cinder/volume/drivers/dell_emc/ps.py

@@ -136,10 +136,11 @@ class PSSeriesISCSIDriver(san.SanISCSIDriver):
                 eqlx_chap_login, and eqlx_chap_password.
         1.4.1 - Rebranded driver to Dell EMC.
         1.4.2 - Enable report discard support.
+        1.4.3 - Report total_volumes in volume stats
 
     """
 
-    VERSION = "1.4.2"
+    VERSION = "1.4.3"
 
     # ThirdPartySytems wiki page
     CI_WIKI_NAME = "Dell_Storage_CI"
@@ -302,6 +303,7 @@ class PSSeriesISCSIDriver(san.SanISCSIDriver):
         data['total_capacity_gb'] = 0
         data['free_capacity_gb'] = 0
         data['multiattach'] = False
+        data['total_volumes'] = 0
 
         provisioned_capacity = 0
 
@@ -316,6 +318,9 @@ class PSSeriesISCSIDriver(san.SanISCSIDriver):
             if line.startswith('VolumeReserve:'):
                 out_tup = line.rstrip().partition(' ')
                 provisioned_capacity = self._get_space_in_gb(out_tup[-1])
+            if line.startswith('TotalVolumes:'):
+                out_tup = line.rstrip().partition(' ')
+                data['total_volumes'] = int(out_tup[-1])
 
         global_capacity = data['total_capacity_gb']
         global_free = data['free_capacity_gb']

releasenotes/notes/ps-report-total-volumes-8aa447c50f2474a7.yaml

@@ -0,0 +1,4 @@
+---
+features:
+  - Dell EMC PS volume driver reports the total number
+    of volumes on the backend in volume stats.