From 2fb9b07ea6646609e4bdf9b08613b3c1d587378e Mon Sep 17 00:00:00 2001
From: Arne Wiebalck <Arne.Wiebalck@cern.ch>
Date: Thu, 20 Nov 2014 08:36:34 +0100
Subject: [PATCH] Add limited retype support for rbd

This patch enables limited retype support for rbd. In addition to
basic retyping between volume types that only differ in their name,
retyping between volume types that imply a change of the qos_specs
are supported. This hence allows to adapt the quality-of-service
settings of a volume after its creation.

All other changes, such as host migration, change of encryption or
changes of settings as defined by the extra_specs are not supported
by this commit and left for later patches.

Implements: blueprint ceph-rbd-support-retype
Change-Id: Ib9edf83eb3ade1e6b2dcf1121a16a6f2e68753e1
---
 cinder/tests/test_rbd.py     | 30 ++++++++++++++++++++++++++++++
 cinder/volume/drivers/rbd.py | 25 +++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/cinder/tests/test_rbd.py b/cinder/tests/test_rbd.py
index 8c721b24f..f40409b46 100644
--- a/cinder/tests/test_rbd.py
+++ b/cinder/tests/test_rbd.py
@@ -736,6 +736,36 @@ class RBDTestCase(test.TestCase):
 
         self.mox.VerifyAll()
 
+    @common_mocks
+    def test_retype(self):
+        context = {}
+        diff = {'encryption': {},
+                'extra_specs': {}}
+        fake_volume = {'name': 'testvolume',
+                       'host': 'currenthost'}
+        fake_type = 'high-IOPS'
+
+        # no support for migration
+        host = {'host': 'anotherhost'}
+        self.assertFalse(self.driver.retype(context, fake_volume,
+                                            fake_type, diff, host))
+        host = {'host': 'currenthost'}
+
+        # no support for changing encryption
+        diff['encryption'] = {'non-empty': 'non-empty'}
+        self.assertFalse(self.driver.retype(context, fake_volume,
+                                            fake_type, diff, host))
+        diff['encryption'] = {}
+
+        # no support for changing extra_specs
+        diff['extra_specs'] = {'non-empty': 'non-empty'}
+        self.assertFalse(self.driver.retype(context, fake_volume,
+                                            fake_type, diff, host))
+        diff['extra_specs'] = {}
+
+        self.assertTrue(self.driver.retype(context, fake_volume,
+                                           fake_type, diff, host))
+
     def test_rbd_volume_proxy_init(self):
         mock_driver = mock.Mock(name='driver')
         mock_driver._connect_to_rados.return_value = (None, None)
diff --git a/cinder/volume/drivers/rbd.py b/cinder/volume/drivers/rbd.py
index 2ccbb0e35..3c7dda251 100644
--- a/cinder/volume/drivers/rbd.py
+++ b/cinder/volume/drivers/rbd.py
@@ -696,6 +696,31 @@ class RBDDriver(driver.VolumeDriver):
                     raise exception.SnapshotIsBusy(snapshot_name=snap_name)
             volume.remove_snap(snap_name)
 
+    def retype(self, context, volume, new_type, diff, host):
+        """Retypes a volume, allows QoS change only."""
+        LOG.debug('Retype volume request %(vol)s to be %(type)s '
+                  '(host: %(host)s), diff %(diff)s.',
+                  {
+                      'vol': volume['name'],
+                      'type': new_type,
+                      'host': host,
+                      'diff': diff
+                  })
+
+        if volume['host'] != host['host']:
+            LOG.error(_LE('Retype with host migration not supported'))
+            return False
+
+        if diff['encryption']:
+            LOG.error(_LE('Retype of encryption type not supported'))
+            return False
+
+        if diff['extra_specs']:
+            LOG.error(_LE('Retype of extra_specs not supported'))
+            return False
+
+        return True
+
     def ensure_export(self, context, volume):
         """Synchronously recreates an export for a logical volume."""
         pass
-- 
2.45.2