the ocd_ibits_known field contains supported MDS inodebits from the client/server and maintained properly on both sides but not used anywhere. The only case is mdc_lock_match() where it is checked to exclude bits not supported on server.
Meanwhile the LOV sets ocd_ibits_known to MDS_INODEBITS_UPDATE only, but MDT-MDT locks can be LOOKUP and XATTR at the same time and everything works just fine.
That makes no sense so cleanup is needed in this area to use ocd_ibits_known properly and check it against enqueued locks.