Remove dm_setup(remove) call in volume_delete.

While it makes sense to perform the dm_setup(remove) before
performing the lvm remove, it seems to cause some buffer IO
errors as evident by kern.log.

I'm also a bit suspicous in that it seems the delete timeouts
we see seems to have increased in frequency with this addition.
I propose this step is removed until we completely understand the
impact of the kernel error on Precise kernels.

Fixes bug: #1075675

Change-Id: I7ae4decea42d8f070d774d3e6376686b3e5b4f83

cinder/volume/driver.py

@@ -152,8 +152,6 @@ class VolumeDriver(object):
         if os.path.exists(dev_path):
             if FLAGS.secure_delete:
                 self._copy_volume('/dev/zero', dev_path, size_in_g)
-            self._try_execute('dmsetup', 'remove', '-f', dev_path,
-                              run_as_root=True)
         self._try_execute('lvremove', '-f', "%s/%s" %
                           (FLAGS.volume_group,
                            self._escape_snapshot(volume['name'])),