Add extend to reference LVM driver

Somwhere along the way we somehow dropped
or missed implementing the extend functionality
in the reference LVM driver.

Add it.

Change-Id: Ib3efe16252b5efacce253688767df426117b2a44
Closes-Bug: #1228358

cinder/brick/local_dev/lvm.py

@@ -434,3 +434,18 @@ def lv_has_snapshot(self, name):
             if (out[0] == 'o') or (out[0] == 'O'):
                 return True
         return False
+
+    def extend_volume(self, lv_name, new_size):
+        """Extend the size of an existing volume."""
+
+        try:
+            self._execute('lvextend', '-L', new_size,
+                          '%s/%s' % (self.vg_name, lv_name),
+                          root_helper=self._root_helper,
+                          run_as_root=True)
+        except putils.ProcessExecutionError as err:
+            LOG.exception(_('Error extending Volume'))
+            LOG.error(_('Cmd     :%s') % err.cmd)
+            LOG.error(_('StdOut  :%s') % err.stdout)
+            LOG.error(_('StdErr  :%s') % err.stderr)
+            raise

cinder/volume/drivers/lvm.py

@@ -371,6 +371,10 @@ def _update_volume_stats(self):
 
         self._stats = data
 
+    def extend_volume(self, volume, new_size):
+        """Extend an existing voumes size."""
+        self.vg.extend_volume(volume['name'], new_size)
+
 
 class LVMISCSIDriver(LVMVolumeDriver, driver.ISCSIDriver):
     """Executes commands relating to ISCSI volumes.

etc/cinder/rootwrap.d/volume.filters

@@ -27,6 +27,9 @@ lvdisplay: CommandFilter, lvdisplay, root
 # cinder/volume/driver.py: 'lvrename', '%(vg)s', '%(orig)s' '(new)s'...
 lvrename: CommandFilter, lvrename, root
 
+# cinder/volume/driver.py: 'lvextend', '-L' '%(new_size)s', '%(lv_name)s' ...
+lvextend: CommandFilter, lvextend, root
+
 # cinder/volume/driver.py: 'iscsiadm', '-m', 'discovery', '-t',...
 # cinder/volume/driver.py: 'iscsiadm', '-m', 'node', '-T', ...
 iscsiadm: CommandFilter, iscsiadm, root
@@ -61,7 +64,7 @@ find: CommandFilter, find, root
 # cinder/volume/drivers/glusterfs.py
 mv: CommandFilter, mv, root
 
-# cinder/volumes/drivers/hds/hds.py: 
+# cinder/volumes/drivers/hds/hds.py:
 hus-cmd: CommandFilter, hus-cmd, root
 
 # cinder/brick/initiator/connector.py: