Fix rebuild with volumes attached

This patch assumes that the correct behavior for instance rebuild is to
maintain attached volumes across a rebuild operation.

Two important changes are:

1) Detaching all volumes during a rebuild so that they won't be 'in-use'
   when prep_block_devices is called to reattach them.

2) xenapi: Allowing additional volumes, not just root volumes, to be
   attached before boot. To handle this, we cycle through all
   block-device-mappings, not just the root-device, create the VDI, and
   later, create the VBD.

Small changes include:

* Using `connection_data` instead of `dev_params` (to match other parts of
  the code base)

* Renaming `get_vdis_for_boot_from_vol` to `get_vdi_uuid_for_volume` to
  reflect its more general and simpler semantics.

Fixes bug 1071547

Change-Id: Ie54a16be4bae2a718ed7d506f32777d0847b9089

nova/block_device.py

@@ -149,23 +149,20 @@ def match_device(device):
     return match.groups()
 
 
-def volume_in_mapping(mount_device, block_device_info, strip=strip_dev):
-    # FIXME(sirp): xen uses strip_prefix to be mountpoint agnostic. There is
-    # probably a better way to handle this so that strip_dev can be used
-    # exclusively.
-    block_device_list = [strip(vol['mount_device'])
+def volume_in_mapping(mount_device, block_device_info):
+    block_device_list = [strip_dev(vol['mount_device'])
                          for vol in
                          driver.block_device_info_get_mapping(
                          block_device_info)]
 
     swap = driver.block_device_info_get_swap(block_device_info)
     if driver.swap_is_usable(swap):
-        block_device_list.append(strip(swap['device_name']))
+        block_device_list.append(strip_dev(swap['device_name']))
 
-    block_device_list += [strip(ephemeral['device_name'])
+    block_device_list += [strip_dev(ephemeral['device_name'])
                           for ephemeral in
                           driver.block_device_info_get_ephemerals(
                           block_device_info)]
 
     LOG.debug(_("block_device_list %s"), block_device_list)
-    return strip(mount_device) in block_device_list
+    return strip_dev(mount_device) in block_device_list

nova/tests/xenapi/test_vm_utils.py

@@ -14,7 +14,7 @@ XENSM_TYPE = 'xensm'
 ISCSI_TYPE = 'iscsi'
 
 
-def get_fake_dev_params(sr_type):
+def get_fake_connection_data(sr_type):
     fakes = {XENSM_TYPE: {'sr_uuid': 'falseSR',
                           'name_label': 'fake_storage',
                           'name_description': 'test purposes',
@@ -73,16 +73,16 @@ class GetInstanceForVdisForSrTestCase(stubs.XenAPITestBase):
 
         self.assertEquals([], result)
 
-    def test_get_vdis_for_boot_from_vol_with_sr_uuid(self):
-        dev_params = get_fake_dev_params(XENSM_TYPE)
+    def test_get_vdi_uuid_for_volume_with_sr_uuid(self):
+        connection_data = get_fake_connection_data(XENSM_TYPE)
         stubs.stubout_session(self.stubs, fake.SessionBase)
         driver = xenapi_conn.XenAPIDriver(False)
 
-        result = vm_utils.get_vdis_for_boot_from_vol(driver._session,
-                                                     dev_params)
-        self.assertEquals(result['root']['uuid'], 'falseVDI')
+        vdi_uuid = vm_utils.get_vdi_uuid_for_volume(
+                driver._session, connection_data)
+        self.assertEquals(vdi_uuid, 'falseVDI')
 
-    def test_get_vdis_for_boot_from_vol_failure(self):
+    def test_get_vdi_uuid_for_volume_failure(self):
         stubs.stubout_session(self.stubs, fake.SessionBase)
         driver = xenapi_conn.XenAPIDriver(False)
 
@@ -90,19 +90,19 @@ class GetInstanceForVdisForSrTestCase(stubs.XenAPITestBase):
             return None
 
         self.stubs.Set(volume_utils, 'introduce_sr', bad_introduce_sr)
-        dev_params = get_fake_dev_params(XENSM_TYPE)
+        connection_data = get_fake_connection_data(XENSM_TYPE)
         self.assertRaises(exception.NovaException,
-                          vm_utils.get_vdis_for_boot_from_vol,
-                          driver._session, dev_params)
+                          vm_utils.get_vdi_uuid_for_volume,
+                          driver._session, connection_data)
 
-    def test_get_vdis_for_boot_from_iscsi_vol_missing_sr_uuid(self):
-        dev_params = get_fake_dev_params(ISCSI_TYPE)
+    def test_get_vdi_uuid_for_volume_from_iscsi_vol_missing_sr_uuid(self):
+        connection_data = get_fake_connection_data(ISCSI_TYPE)
         stubs.stubout_session(self.stubs, fake.SessionBase)
         driver = xenapi_conn.XenAPIDriver(False)
 
-        result = vm_utils.get_vdis_for_boot_from_vol(driver._session,
-                                                     dev_params)
-        self.assertNotEquals(result['root']['uuid'], None)
+        vdi_uuid = vm_utils.get_vdi_uuid_for_volume(
+                driver._session, connection_data)
+        self.assertNotEquals(vdi_uuid, None)
 
 
 class VMRefOrRaiseVMFoundTestCase(test.TestCase):