From 4f3291e3795460f0b8da5a029faa2e4a9271c8a9 Mon Sep 17 00:00:00 2001 From: Rick Harris Date: Tue, 31 Jul 2012 22:49:13 +0000 Subject: XenAPI: Fix race-condition with cached images. The core problem is that XenServer's `VDI.copy` call drops the destination file directly into the SR. This means that half-completed files are visible with no way to distinguish these from fully-copied files. We had some code that attempted to mitigate this issue by checking physical_utilisation against an expected value. The problem with this code is that it didn't account for VDI chaining where the physical_utilisation would not necessarily match the parent. The net effect of this was that 'cloned' VDIs would never be found because their physical_utilisation was far below what was expected. The work around is to create our own `_safe_copy_vdi` which is isolated and atomic. Long term, `VDI.copy` should be fixed so that half-completed files are never stored in the SR. Change-Id: I6eb3cb5259f9ee1c7394e58f76105a8b39bfc720 --- .../rpmbuild/SPECS/openstack-xen-plugins.spec | 1 + .../xenapi/etc/xapi.d/plugins/workarounds | 65 ++++++++++++++++++++++ 2 files changed, 66 insertions(+) create mode 100755 plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds (limited to 'plugins') diff --git a/plugins/xenserver/xenapi/contrib/rpmbuild/SPECS/openstack-xen-plugins.spec b/plugins/xenserver/xenapi/contrib/rpmbuild/SPECS/openstack-xen-plugins.spec index 8f4415311..63b5e71d3 100644 --- a/plugins/xenserver/xenapi/contrib/rpmbuild/SPECS/openstack-xen-plugins.spec +++ b/plugins/xenserver/xenapi/contrib/rpmbuild/SPECS/openstack-xen-plugins.spec @@ -33,6 +33,7 @@ rm -rf $RPM_BUILD_ROOT /etc/xapi.d/plugins/kernel /etc/xapi.d/plugins/migration /etc/xapi.d/plugins/pluginlib_nova.py +/etc/xapi.d/plugins/workarounds /etc/xapi.d/plugins/xenhost /etc/xapi.d/plugins/xenstore.py /etc/xapi.d/plugins/utils.py diff --git a/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds b/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds new file mode 100755 index 000000000..611436539 --- /dev/null +++ b/plugins/xenserver/xenapi/etc/xapi.d/plugins/workarounds @@ -0,0 +1,65 @@ +#!/usr/bin/env python + +# Copyright (c) 2012 Openstack, LLC +# All Rights Reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); you may +# not use this file except in compliance with the License. You may obtain +# a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT +# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the +# License for the specific language governing permissions and limitations +# under the License. + +"""Handle the uploading and downloading of images via Glance.""" + +import cPickle as pickle +try: + import json +except ImportError: + import simplejson as json +import os +import shutil + +import XenAPIPlugin + +import utils + +#FIXME(sirp): should this use pluginlib from 5.6? +from pluginlib_nova import * +configure_logging('hacks') + + +def _copy_vdis(sr_path, staging_path, vdi_uuids): + seq_num = 0 + for vdi_uuid in vdi_uuids: + src = os.path.join(sr_path, "%s.vhd" % vdi_uuid) + dst = os.path.join(staging_path, "%d.vhd" % seq_num) + shutil.copyfile(src, dst) + seq_num += 1 + + +def safe_copy_vdis(session, args): + params = pickle.loads(exists(args, 'params')) + sr_path = params["sr_path"] + vdi_uuids = params["vdi_uuids"] + uuid_stack = params["uuid_stack"] + + staging_path = utils.make_staging_area(sr_path) + try: + _copy_vdis(sr_path, staging_path, vdi_uuids) + imported_vhds = utils.import_vhds(sr_path, staging_path, uuid_stack) + finally: + utils.cleanup_staging_area(staging_path) + + # Right now, it's easier to return a single string via XenAPI, + # so we'll json encode the list of VHDs. + return json.dumps(imported_vhds) + + +if __name__ == '__main__': + XenAPIPlugin.dispatch({'safe_copy_vdis': safe_copy_vdis}) -- cgit