Dell PowerStore: Volume caching exception support

Fixed volume caching in PowerStore driver. Volume caching stops working
after 32nd volume created from the same image due to snapshot limit per
volume in PowerStore. The driver needs to throw exception
SnapshotLimitReached to invalidate cache and start over with new volume
snapshots.

Closes-Bug: #1962824
Change-Id: I8b46d443a75bf98260394552f77c6807e405dce7

cinder/tests/unit/volume/drivers/dell_emc/powerstore/test_volume_create_from_source.py

@@ -19,6 +19,7 @@ from cinder import exception
 from cinder.tests.unit import fake_snapshot
 from cinder.tests.unit import fake_volume
 from cinder.tests.unit.volume.drivers.dell_emc import powerstore
+from cinder.volume.drivers.dell_emc.powerstore import client
 
 
 class TestVolumeCreateFromSource(powerstore.TestPowerStoreDriver):
@@ -114,3 +115,26 @@ class TestVolumeCreateFromSource(powerstore.TestPowerStoreDriver):
             self.source_volume
         )
         self.assertIn("Failed to extend PowerStore volume", error.msg)
+
+    @mock.patch("requests.request")
+    def test_create_snapshot_limit_reached(self, mock_create_snap_limit):
+        snapshot_limit_reached_response = {
+            'errorCode': 0,
+            'message': 'messages',
+            'messages': [
+                {
+                    'code': client.TOO_MANY_SNAPS_ERROR,
+                }
+            ]
+        }
+        mock_create_snap_limit.return_value = powerstore.MockResponse(
+            snapshot_limit_reached_response, rc=400)
+        error = self.assertRaises(
+            exception.SnapshotLimitReached,
+            self.driver.adapter.create_volume_from_source,
+            self.volume,
+            self.source_volume
+        )
+        self.assertIn(
+            "Exceeded the configured limit of 32 snapshots per volume.",
+            error.msg)

cinder/volume/drivers/dell_emc/powerstore/client.py

@@ -31,6 +31,8 @@ from cinder.volume.drivers.dell_emc.powerstore import utils
 LOG = logging.getLogger(__name__)
 VOLUME_NOT_MAPPED_ERROR = "0xE0A08001000F"
 SESSION_ALREADY_FAILED_OVER_ERROR = "0xE0201005000C"
+TOO_MANY_SNAPS_ERROR = "0xE0A040010003"
+MAX_SNAPS_IN_VTREE = 32
 
 
 class PowerStoreClient(object):
@@ -271,6 +273,10 @@ class PowerStoreClient(object):
                       "entity": entity,
                       "entity_id": entity_id, })
             LOG.error(msg)
+            if ("messages" in response and
+                    response["messages"][0]["code"] == TOO_MANY_SNAPS_ERROR):
+                raise exception.SnapshotLimitReached(
+                    set_limit=MAX_SNAPS_IN_VTREE)
             raise exception.VolumeBackendAPIException(data=msg)
         return response["id"]
 

releasenotes/notes/bug-1962824-ff0cac0d35021f84.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    PowerStore driver `bug #1962824
+    <https://bugs.launchpad.net/cinder/+bug/1962824>`_: Fixed Cinder
+    volume caching mechanism for the driver. Now the driver
+    correctly raises ``exception.SnapshotLimitReached`` when maximum
+    snapshots are created for a given volume and the volume cache is
+    invalidated to allow a new row of fast volume clones.