xenapi: Refactor snapshots during resize

Currently, we use VM.snapshot for resize, which fails if we have a
volume attached to the VM, which does not support snapshots. This change
uses VDI.snapshot instead, for all VDIs that are not attached by nova.

Also needed for xenapi: detaching and reattaching volumes during
migrations and reverting of migrations.

Fixes Bug #1028092

Change-Id: I3e2973747135a9c33de194e38537620c397bb87e
(cherry picked from commit 3595275)

nova/compute/manager.py

@@ -790,8 +790,10 @@ def _get_instance_volume_bdm(self, context, instance_uuid, volume_id):
             if str(bdm['volume_id']) == str(volume_id):
                 return bdm
 
-    def _get_instance_volume_block_device_info(self, context, instance_uuid):
-        bdms = self._get_instance_volume_bdms(context, instance_uuid)
+    def _get_instance_volume_block_device_info(self, context, instance_uuid,
+                                               bdms=None):
+        if bdms is None:
+            bdms = self._get_instance_volume_bdms(context, instance_uuid)
         block_device_mapping = []
         for bdm in bdms:
             try:
@@ -850,7 +852,7 @@ def _shutdown_instance(self, context, instance):
         # NOTE(vish) get bdms before destroying the instance
         bdms = self._get_instance_volume_bdms(context, instance['uuid'])
         block_device_info = self._get_instance_volume_block_device_info(
-            context, instance['uuid'])
+            context, instance['uuid'], bdms=bdms)
         self.driver.destroy(instance, self._legacy_nw_info(network_info),
                             block_device_info)
         for bdm in bdms:
@@ -1441,6 +1443,14 @@ def revert_resize(self, context, instance, migration_id,
 
             self.driver.destroy(instance, self._legacy_nw_info(network_info),
                                 block_device_info)
+            # Terminate volume connections.
+            bdms = self._get_instance_volume_bdms(context, instance['uuid'])
+            if bdms:
+                connector = self.driver.get_volume_connector(instance)
+                for bdm in bdms:
+                    volume = self.volume_api.get(context, bdm['volume_id'])
+                    self.volume_api.terminate_connection(context, volume,
+                            connector)
             self.compute_rpcapi.finish_revert_resize(context, instance,
                     migration_ref['id'], migration_ref['source_compute'],
                     reservations)
@@ -1468,8 +1478,15 @@ def finish_revert_resize(self, context, migration_id, instance,
             old_instance_type = migration_ref['old_instance_type_id']
             instance_type = instance_types.get_instance_type(old_instance_type)
 
+            bdms = self._get_instance_volume_bdms(context, instance['uuid'])
             block_device_info = self._get_instance_volume_block_device_info(
-                                context, instance['uuid'])
+                    context, instance['uuid'])
+            if bdms:
+                connector = self.driver.get_volume_connector(instance)
+                for bdm in bdms:
+                    volume = self.volume_api.get(context, bdm['volume_id'])
+                    self.volume_api.initialize_connection(context, volume,
+                                                          connector)
 
             self.driver.finish_revert_migration(instance,
                                        self._legacy_nw_info(network_info),
@@ -1593,6 +1610,15 @@ def resize_instance(self, context, instance,
                     instance_type_ref, self._legacy_nw_info(network_info),
                     block_device_info)
 
+            # Terminate volume connections.
+            bdms = self._get_instance_volume_bdms(context, instance['uuid'])
+            if bdms:
+                connector = self.driver.get_volume_connector(instance)
+                for bdm in bdms:
+                    volume = self.volume_api.get(context, bdm['volume_id'])
+                    self.volume_api.terminate_connection(context, volume,
+                            connector)
+
             self.db.migration_update(context,
                                      migration_id,
                                      {'status': 'post-migrating'})
@@ -1640,8 +1666,16 @@ def _finish_resize(self, context, instance, migration_ref, disk_info,
             context, instance, "finish_resize.start",
             network_info=network_info)
 
+        bdms = self._get_instance_volume_bdms(context, instance['uuid'])
         block_device_info = self._get_instance_volume_block_device_info(
-                            context, instance['uuid'])
+                            context, instance['uuid'], bdms=bdms)
+
+        if bdms:
+            connector = self.driver.get_volume_connector(instance)
+            for bdm in bdms:
+                volume = self.volume_api.get(context, bdm['volume_id'])
+                self.volume_api.initialize_connection(context, volume,
+                                                      connector)
 
         self.driver.finish_migration(context, migration_ref, instance,
                                      disk_info,

nova/tests/test_xenapi.py

@@ -358,7 +358,8 @@ def fake_get_rrd(host, vm_uuid):
         self.assertDictMatch(fake_diagnostics, expected)
 
     def test_instance_snapshot_fails_with_no_primary_vdi(self):
-        def create_bad_vbd(vm_ref, vdi_ref):
+        def create_bad_vbd(session, vm_ref, vdi_ref, userdevice,
+                           vbd_type='disk', read_only=False, bootable=False):
             vbd_rec = {'VM': vm_ref,
                'VDI': vdi_ref,
                'userdevice': 'fake',
@@ -367,7 +368,7 @@ def create_bad_vbd(vm_ref, vdi_ref):
             xenapi_fake.after_VBD_create(vbd_ref, vbd_rec)
             return vbd_ref
 
-        self.stubs.Set(xenapi_fake, 'create_vbd', create_bad_vbd)
+        self.stubs.Set(vm_utils, 'create_vbd', create_bad_vbd)
         stubs.stubout_instance_snapshot(self.stubs)
         # Stubbing out firewall driver as previous stub sets alters
         # xml rpc result parsing

nova/virt/xenapi/driver.py

@@ -188,13 +188,27 @@ def finish_revert_migration(self, instance, network_info,
         """Finish reverting a resize, powering back on the instance"""
         # NOTE(vish): Xen currently does not use network info.
         self._vmops.finish_revert_migration(instance)
+        block_device_mapping = driver.block_device_info_get_mapping(
+                block_device_info)
+        for vol in block_device_mapping:
+            connection_info = vol['connection_info']
+            mount_device = vol['mount_device'].rpartition("/")[2]
+            self._volumeops.attach_volume(connection_info,
+                    instance['name'], mount_device)
 
     def finish_migration(self, context, migration, instance, disk_info,
                          network_info, image_meta, resize_instance=False,
                          block_device_info=None):
         """Completes a resize, turning on the migrated instance"""
         self._vmops.finish_migration(context, migration, instance, disk_info,
                                      network_info, image_meta, resize_instance)
+        block_device_mapping = driver.block_device_info_get_mapping(
+                block_device_info)
+        for vol in block_device_mapping:
+            connection_info = vol['connection_info']
+            mount_device = vol['mount_device'].rpartition("/")[2]
+            self._volumeops.attach_volume(connection_info,
+                    instance['name'], mount_device)
 
     def snapshot(self, context, instance, image_id):
         """ Create snapshot from a running VM instance """
@@ -237,8 +251,17 @@ def migrate_disk_and_power_off(self, context, instance, dest,
         """Transfers the VHD of a running instance to another host, then shuts
         off the instance copies over the COW disk"""
         # NOTE(vish): Xen currently does not use network info.
-        return self._vmops.migrate_disk_and_power_off(context, instance,
-                                                      dest, instance_type)
+        rv = self._vmops.migrate_disk_and_power_off(context, instance,
+                                                    dest, instance_type)
+        block_device_mapping = driver.block_device_info_get_mapping(
+                block_device_info)
+        name_label = self._vmops._get_orig_vm_name_label(instance)
+        for vol in block_device_mapping:
+            connection_info = vol['connection_info']
+            mount_device = vol['mount_device'].rpartition("/")[2]
+            self._volumeops.detach_volume(connection_info,
+                    name_label, mount_device)
+        return rv
 
     def suspend(self, instance):
         """suspend the specified instance"""

nova/virt/xenapi/vm_utils.py

@@ -524,39 +524,51 @@ def snapshot_attached_here(session, instance, vm_ref, label):
     vm_vdi_ref, vm_vdi_rec = get_vdi_for_vm_safely(session, vm_ref)
     original_parent_uuid = _get_vhd_parent_uuid(session, vm_vdi_ref)
 
-    template_vm_ref, template_vdi_uuid = _create_snapshot(
-            session, instance, vm_ref, label)
-
     try:
+        vdi_snapshot_recs = _vdi_snapshot_vm_base(session, instance, vm_ref)
         sr_ref = vm_vdi_rec["SR"]
         parent_uuid, base_uuid = _wait_for_vhd_coalesce(
                 session, instance, sr_ref, vm_vdi_ref, original_parent_uuid)
 
-        vdi_uuids = [vdi_rec['uuid'] for vdi_rec in
-                     _walk_vdi_chain(session, template_vdi_uuid)]
+        vdi_uuids = []
+        for snapshot in vdi_snapshot_recs:
+            vdi_uuids += [vdi_rec['uuid'] for vdi_rec in
+                         _walk_vdi_chain(session, snapshot['uuid'])]
 
         yield vdi_uuids
     finally:
-        _destroy_snapshot(session, instance, template_vm_ref)
-
-
-def _create_snapshot(session, instance, vm_ref, label):
-    template_vm_ref = session.call_xenapi('VM.snapshot', vm_ref, label)
-    template_vdi_rec = get_vdi_for_vm_safely(session, template_vm_ref)[1]
-    template_vdi_uuid = template_vdi_rec["uuid"]
+        _destroy_snapshots(session, instance, vdi_snapshot_recs)
 
-    LOG.debug(_("Created snapshot %(template_vdi_uuid)s with label"
-                " '%(label)s'"), locals(), instance=instance)
 
-    return template_vm_ref, template_vdi_uuid
+def _vdi_snapshot_vm_base(session, instance, vm_ref):
+    """Make a snapshot of every non-cinder VDI and return a list
+    of the new vdi records.
+    """
+    new_vdis = []
+    try:
+        vbd_refs = session.call_xenapi("VM.get_VBDs", vm_ref)
+        for vbd_ref in vbd_refs:
+            oc = session.call_xenapi("VBD.get_other_config", vbd_ref)
+            if 'osvol' not in oc:
+                # This volume is not a nova/cinder volume
+                vdi_ref = session.call_xenapi("VBD.get_VDI", vbd_ref)
+                snapshot_ref = session.call_xenapi("VDI.snapshot", vdi_ref,
+                                                   {})
+                new_vdis.append(session.call_xenapi("VDI.get_record",
+                                                    snapshot_ref))
+
+    except session.XenAPI.Failure:
+        LOG.exception(_("Failed to snapshot VDI"), instance=instance)
+        raise
+    finally:
+        return new_vdis
 
 
-def _destroy_snapshot(session, instance, vm_ref):
-    vdi_refs = lookup_vm_vdis(session, vm_ref)
+def _destroy_snapshots(session, instance, vdi_snapshot_recs):
+    vdi_refs = [session.call_xenapi("VDI.get_by_uuid", vdi_rec['uuid'])
+                 for vdi_rec in vdi_snapshot_recs]
     safe_destroy_vdis(session, vdi_refs)
 
-    destroy_vm(session, instance, vm_ref)
-
 
 def get_sr_path(session):
     """Return the path to our storage repository

nova/virt/xenapi/vmops.py

@@ -196,10 +196,26 @@ def finish_migration(self, context, migration, instance, disk_info,
         if resize_instance:
             self._resize_instance(instance, root_vdi)
 
+        # Check if kernel and ramdisk are external
+        kernel_file = None
+        ramdisk_file = None
+
+        name_label = instance['name']
+        if instance['kernel_id']:
+            vdis = vm_utils.create_kernel_image(context, self._session,
+                        instance, name_label, instance['kernel_id'],
+                        vm_utils.ImageType.KERNEL)
+            kernel_file = vdis['kernel'].get('file')
+        if instance['ramdisk_id']:
+            vdis = vm_utils.create_kernel_image(context, self._session,
+                        instance, name_label, instance['ramdisk_id'],
+                        vm_utils.ImageType.RAMDISK)
+            ramdisk_file = vdis['ramdisk'].get('file')
+
         vm_ref = self._create_vm(context, instance, instance['name'],
                                  {'root': root_vdi},
-                                 network_info, image_meta)
-
+                                 network_info, image_meta, kernel_file,
+                                 ramdisk_file)
         # 5. Start VM
         self._start(instance, vm_ref=vm_ref)
         self._update_instance_progress(context, instance,

nova/virt/xenapi/volumeops.py

@@ -215,8 +215,10 @@ def detach_volume(self, connection_info, instance_name, mountpoint):
             raise Exception(_('Unable to locate volume %s') % mountpoint)
 
         try:
+            vm_rec = self._session.call_xenapi("VM.get_record", vm_ref)
             sr_ref = volume_utils.find_sr_from_vbd(self._session, vbd_ref)
-            vm_utils.unplug_vbd(self._session, vbd_ref)
+            if vm_rec['power_state'] != 'Halted':
+                vm_utils.unplug_vbd(self._session, vbd_ref)
         except volume_utils.StorageError, exc:
             LOG.exception(exc)
             raise Exception(_('Unable to detach volume %s') % mountpoint)