quotacheck speed

[Peter Grandi]

>> When mounting 800GB filesystem (after repair for example)
>> here quotacheck takes 10 minutes. Quite long time that adds
>> to whole time of filesystem downtime (repair + quotacheck).

For tight downtime minimization requirements wishful thinking is
not a strategy: whole filetree metadata scans are not cheap. If
you require fast scan of metadata of the whole filetree, ensure
filetrees don't have a lot of metadata (or fund the development
of a parallel whole tree metadata scanner).

Also 10 minutes is not that long; file system checks/repairs can
take days or weeks.

>> I wonder if quotacheck can be somehow improved or done
>> differently like doing it in parallel with normal fs usage
>> (so there will be no downtime) ?