dovecot - Dec 2010 - Quota Calculation seems to be wrong when using dsync

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Recently I encountered odd quota increases when using 'dsync' with the
latest and greatest: 2.0.8 (89936539e3b8).

Say you got something in place like this:

plugin {
  quota = dict:user::file:%h/mdbox/dovecot-quota
  quota_rule = *:storage=1GB
  quota_rule2 = Trash:storage=+10%%
}

Kick off a manual backup:

$ dsync -u user at domain.tld backup mdbox:/<path to backup>/mdbox

This results in doubling the quota for the backed up user. It doesn't seem
to matter whether 'mirror' or 'backup' mode is used, both
increase the "source" quota. Doesn't sound right to me. You can
only get to the "real" usage by running a recalc manually:

$ doveadm quota recalc -u user at domain.tld

Anyone else seen this?

Regards
Thomas

P.S. Merry Christmas
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On Sat, 2010-12-25 at 10:08 +0100, Thomas Leuxner wrote:
> plugin {
>   quota = dict:user::file:%h/mdbox/dovecot-quota
>   quota_rule = *:storage=1GB
>   quota_rule2 = Trash:storage=+10%%
> }
> 
> Kick off a manual backup:
> 
> $ dsync -u user at domain.tld backup mdbox:/<path to backup>/mdbox
> 
> This results in doubling the quota for the backed up user.
This is problematic. With dict quota you'll have this problem, because
both source and destination uses the same file. So it would kind of make
sense to disable quota for the destination dsync.. Except with Maildir++
the quota is stored in the Maildir root directory. There are no problems
with dsyncing it, and you most likely wouldn't want quota disabled
there.

So .. I'm not really sure what I can do about this. There are some
workarounds you could do, like:

dsync -u user at domain.tld backup dsync -o mail=mdbox:/<path to
backup>/mdbox -o plugin/quota
(works only with latest 2.0/2.1 hg, but with older versions you could do
e.g. -o mail_plugins=)

Still, it would be nice if there was some generic solution to this.
Perhaps the destination username should be something different, like
"backup". In dict-sql case then it would modify "backup"
user's quota.
For dict-file the %h could maybe expand to backup user's homedir.. The
backup username probably should be a parameter to dsync I guess.. But an
extra parameter wouldn't fix this automatically..