Add capabilities reporting to ThinLVM driver

ThinLVM driver was missing the newly required capabilities reporting
and inheritance from the parent LVM driver doesn't work because the
capacity reporting methods between regular LVM and Thin LVM are not
compatible.

This patch add the basic requirements needed in the capabilities reporting
to make it usable by the filter scheduler.

Fixes bug: 1166572

Change-Id: I471dcc31d07516e71bcd2d3ae03e0405e0594697
(cherry picked from commit a95a214)

cinder/volume/drivers/lvm.py

@@ -63,6 +63,9 @@
 
 class LVMVolumeDriver(driver.VolumeDriver):
     """Executes commands relating to Volumes."""
+
+    VERSION = '1.0'
+
     def __init__(self, *args, **kwargs):
         super(LVMVolumeDriver, self).__init__(*args, **kwargs)
         self.configuration.append_config_values(volume_opts)
@@ -559,7 +562,7 @@ def _update_volume_status(self):
         backend_name = self.configuration.safe_get('volume_backend_name')
         data["volume_backend_name"] = backend_name or 'LVM_iSCSI'
         data["vendor_name"] = 'Open Source'
-        data["driver_version"] = '1.0'
+        data["driver_version"] = self.VERSION
         data["storage_protocol"] = 'iSCSI'
 
         data['total_capacity_gb'] = 0
@@ -593,6 +596,9 @@ def _iscsi_authentication(self, chap, name, password):
 
 class ThinLVMVolumeDriver(LVMISCSIDriver):
     """Subclass for thin provisioned LVM's."""
+
+    VERSION = '1.0'
+
     def __init__(self, *args, **kwargs):
         super(ThinLVMVolumeDriver, self).__init__(*args, **kwargs)
 
@@ -651,3 +657,28 @@ def create_snapshot(self, snapshot):
         """Creates a snapshot of a volume."""
         orig_lv_name = "%s/%s" % (FLAGS.volume_group, snapshot['volume_name'])
         self._do_lvm_snapshot(orig_lv_name, snapshot)
+
+    def get_volume_stats(self, refresh=False):
+        """Get volume status.
+        If 'refresh' is True, run update the stats first."""
+        if refresh:
+            self._update_volume_status()
+
+        return self._stats
+
+    def _update_volume_status(self):
+        """Retrieve status info from volume group."""
+
+        LOG.debug(_("Updating volume status"))
+        data = {}
+
+        backend_name = self.configuration.safe_get('volume_backend_name')
+        data["volume_backend_name"] = backend_name or self.__class__.__name__
+        data["vendor_name"] = 'Open Source'
+        data["driver_version"] = self.VERSION
+        data["storage_protocol"] = 'iSCSI'
+        data['reserved_percentage'] = self.configuration.reserved_percentage
+        data['QoS_support'] = False
+        data['total_capacity_gb'] = 'infinite'
+        data['free_capacity_gb'] = 'infinite'
+        self._stats = data