My only concern with an ondisk compat change like this is we break
downgrade (e.g., from 12.2.10 to 12.2.9 or whatever). I think repeating
the reconciliation on every startup is a small price to pay to avoid that
concern. Or, maybe we only repeat the reconciliation on mimic and
luminous but not on nautilus? Regardless, I think it is cheap: we've
already loaded all the freelist state into memory. It might not be
worth the effort to skip it.
I'm afraid it wouldn't help - reconciliation is able to recover from DB
to BlueFS only. I.e. it assumes DB replica is always valid while BlueFS
might be incomplete.
That's not the case for us here.
