[LU-1412] Add llog subsystem to OFD to cancel unlink/setattr cookies

• Type: Technical task
• Resolution: Won't Fix
• Priority: Major
• Affects Version/s: Lustre 2.3.0
• Story Points: 2
• Assignee: Mikhail Pershin
• Reporter: Mikhail Pershin

Description

Currently, the OFD code will discard llog cookies sent from the client, and not send any cookies back to the MDS when objects are destroyed. This means that the MDS will accumulate cookies for all unlinked objects, and startup times will become progressively slower on a filesystem using OFD as the MDS tries to unlink ALL previously destroyed objects on every reconnect. Eventually, the MDS unlink llog will become full and unlinks may fail, after about 65000^2 objects per OST.

For OFD to be usable in a real 2.3 system, this will need to be handled in some way, either by the MDS detecting that the OST is not using llog cookies, or by the OFD/OST code sending the unlink cookies back to the MDS.

Issue Links

• is related to: LU-1545 Implement procfs entry "mds_sync" in OFD