[LU-17960] LAST_ID mismatch improvement

• Type: Bug
• Resolution: Unresolved
• Priority: Minor
• Severity: 3
• Assignee: Lai Siyao
• Reporter: Lai Siyao

Description

Normally if LAST_ID known by MDT and OST shouldn't differ too much, and if the one in lov_objid (on MDT) is OST_MAX_PRECREATE (20000) behind the LAST_ID on OST, it's not handled currently because it's hard to tell which one is corrupt.

This can be improved in two aspects:
1. "lfsck -t layout" should update LAST_ID with the known max ID. (it's not updated if it's not less than the known max ID), so after lfsck this LAST_ID is correct.
2. once lfsck has finished check, trust the LAST_ID on OST, and reply it to MDT on precreate, and MDT will use it instead of its own.

Issue Links

• is related to: LU-17987 always trust OST last_id in normal precreate

Comments

[Lai Siyao]

Actually the last created FID on OSP is from OST, and only in deleting orphans phase in the first precreate, it will use the last used FID in 'lovobj_id'. So this improvement is actually for the deleting orphan phase, and for the mismatch issue found on customer site, we can always trust the last created FID on OST, because it's maintained in memory, not just read from disk (which happens in deleting phase). I'll file another ticket for this.