EMC ScaleIO driver does not honor create from snapshot volume size

create_volume_from_snapshot can specify a volume size
larger than the orginal snapshot.
Current code does not appear to handle this size difference.
This patch addresses the issue.

Change-Id: Ifa247ef0eec00c23afe6f875107a06f756bc180e
Closes-Bug: #1560649

cinder/tests/unit/volume/drivers/dell_emc/scaleio/test_create_volume_from_snapshot.py

@@ -98,3 +98,8 @@ class TestCreateVolumeFromSnapShot(scaleio.TestScaleIODriver):
     def test_create_volume_from_snapshot(self):
         self.set_https_response_mode(self.RESPONSE_MODE.Valid)
         self.driver.create_volume_from_snapshot(self.volume, self.snapshot)
+
+    def test_create_volume_from_snapshot_larger(self):
+        self.set_https_response_mode(self.RESPONSE_MODE.Valid)
+        self.volume.size = 2
+        self.driver.create_volume_from_snapshot(self.volume, self.snapshot)

cinder/volume/drivers/dell_emc/scaleio/driver.py

@@ -788,7 +788,15 @@ class ScaleIODriver(driver.VolumeDriver):
                  {'volname': volume_id,
                   'snapname': snapname})
 
-        return self._snapshot_volume(volume_id, snapname)
+        ret = self._snapshot_volume(volume_id, snapname)
+        if volume.size > snapshot.volume_size:
+            LOG.info("Extending volume %(vol)s to size %(size)s",
+                     {'vol': ret['provider_id'],
+                      'size': volume.size})
+            self._extend_volume(ret['provider_id'],
+                                snapshot.volume_size, volume.size)
+
+        return ret
 
     @staticmethod
     def _get_headers():

releasenotes/notes/bug-1560649-d4f3ff71fe4ddb89.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Dell EMC Scale IO Driver: Fixes `bug 1560649
+    <https://bugs.launchpad.net/cinder/+bug/1560649>`
+    for creating volumes with sizes greater than that of the
+    original snapshot.