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.