Public bug reported: The method here:
https://github.com/openstack/nova/blob/9f2e0ea1ce2792505cdae6e8f3cce9e32845ea64/nova/objects/block_device.py#L200 Allows getting a BDM with or without an instance_uuid. There is no unique constraint on the block_device_mappings table, so we could potentially have a race here where some code calls this without an instance uuid (which there are several in the compute API and manager) and we could have multiple BDMs mapped to the same volume_id in the database. We get one back and the .first() call in the DB API hides that we're corrupt: https://github.com/openstack/nova/blob/master/nova/db/sqlalchemy/api.py#L4035 So what we need to do is be explicit about calling this kind of method. This is also related to the multiattach series here: https://review.openstack.org/#/q/topic:bp/volume-multi-attach Because after that series we'll be able to associate the same volume_id to multiple instances (by design). So we need to: 1. deprecate the existing bdm.get_by_volume_id method 2. add a new method which takes volume_id and instance_uuid (not optional) and returns a single BDM for those. 3. add a new method which takes only volume_id (no instance uuid) and if we get multiple BDMs back from the database, it raises an error because we should only get one, else the DB is corrupt. 4. change all of code that's calling (1) to all the new methods in (2) or (3). This should help us move forward on the multiattach blueprint in the Newton release. ** Affects: nova Importance: Medium Assignee: Dan Smith (danms) Status: Triaged ** Tags: db unified-objects volumes ** Changed in: nova Status: New => Triaged ** Changed in: nova Importance: Undecided => Medium ** Changed in: nova Assignee: (unassigned) => Dan Smith (danms) -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1533834 Title: nova.objects.BlockDeviceMapping.get_by_volume_id can be racy and should be deprecated Status in OpenStack Compute (nova): Triaged Bug description: The method here: https://github.com/openstack/nova/blob/9f2e0ea1ce2792505cdae6e8f3cce9e32845ea64/nova/objects/block_device.py#L200 Allows getting a BDM with or without an instance_uuid. There is no unique constraint on the block_device_mappings table, so we could potentially have a race here where some code calls this without an instance uuid (which there are several in the compute API and manager) and we could have multiple BDMs mapped to the same volume_id in the database. We get one back and the .first() call in the DB API hides that we're corrupt: https://github.com/openstack/nova/blob/master/nova/db/sqlalchemy/api.py#L4035 So what we need to do is be explicit about calling this kind of method. This is also related to the multiattach series here: https://review.openstack.org/#/q/topic:bp/volume-multi-attach Because after that series we'll be able to associate the same volume_id to multiple instances (by design). So we need to: 1. deprecate the existing bdm.get_by_volume_id method 2. add a new method which takes volume_id and instance_uuid (not optional) and returns a single BDM for those. 3. add a new method which takes only volume_id (no instance uuid) and if we get multiple BDMs back from the database, it raises an error because we should only get one, else the DB is corrupt. 4. change all of code that's calling (1) to all the new methods in (2) or (3). This should help us move forward on the multiattach blueprint in the Newton release. To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1533834/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
