[BUG?] Double quota calulation when special folder is present

[Mark Moseley]

On Wed, Mar 20, 2019 at 2:13 PM Mark Moseley <moseleymark at gmail.com> wrote:

> Just hoping to get some dev eyes on this. I'm incredibly reluctant to
> throw the word 'bug' around
> (since 99 times out of 100, it's not -- it's almost always the config),
> but I can't think of any way
> that this could be a config issue, esp when the pre-2.2.34 version works
> as expected.
>
> I noticed during troubleshooting that dovecot errors out if I try to
> create a subfolder called
> 'INBOX' but it'll happily create a subfolder called INBOX.SomethingElse
> (i.e. a folder called
> INBOX.INBOX.SomethingElse - resulting in a directory called
> .INBOX.SomethingElse on the
> filesystem, and leading to the problem described below). Is that
> sub-subfolder creation (where
> the top level subfolder matches the namespace name) supposed to be
> allowed? It seems
> odd that 'INBOX' (as a subfolder of INBOX) would be blocked but
> INBOX.SomethingElse (as
> a subfolder of INBOX) would be allowed. I'd expect INBOX.SomethingElse
> (i.e.
> INBOX.INBOX.SomethingElse) would be blocked as well.
>
>
> On Wed, Mar 13, 2019 at 4:46 AM Bernd Wurst via dovecot <
> dovecot at dovecot.org> wrote:
>
>> Hello,
>>
>> we're operating dovecot on a small server. Some years ago, we migrated
>> from courier IMAP to dovecot. Therefore, we defined our default
>> Namespace "inbox" with prefix "INBOX." to have this compatible. I found
>> this in some migration docs those days. Generally, everything worked as
>> expected.
>>
>> Our only namespace is configured like this:
>>
>> namespace inbox {
>>  separator = .
>>   prefix = INBOX.
>>   inbox = yes
>> }
>>
>> Regularly, there is no folder named INBOX or .INBOX in the file system,
>> I suppose this is correct.  But I found a special corner case today when
>> it comes to quota calculation.
>>
>> When - for whatever reason - a folder .INBOX.foo (for arbitrary values
>> of foo) exists, the whole mailbox is counted twice in quota
>> recalculation. Just creating .INBOX does nothing but a subfolder
>> triggers the problem.
>>
>> This is my shell view (replaced username and file path and deleted
>> unnecessary debug output)
>>
>> $ cat maildirsize
>> 268435456S
>> 14697 17
>> $ maildirmake .INBOX.foo
>> $ sudo doveadm -D quota recalc -u <user>
>> [...]
>> doveadm(<user>): Debug: Namespace inbox: type=private, prefix=INBOX.,
>> sep=., inbox=yes, hidden=no, list=yes, subscriptions=yes
>> location=maildir:/home/.../test
>> doveadm(<user>): Debug: maildir++: root=/home/.../test, index=,
>> indexpvt=, control=, inbox=/home/.../test, alt=
>> doveadm(<user>): Debug: Namespace : type=private, prefix=, sep=,
>> inbox=no, hidden=yes, list=no, subscriptions=no location=fail::LAYOUT=none
>> doveadm(<user>): Debug: none: root=, index=, indexpvt=, control=,
>> inbox=, alt=
>> doveadm(<user>): Debug: quota: quota_over_flag check: quota_over_script
>> unset - skipping
>> doveadm(<user>): Debug: Quota root User quota: Recalculated relative
>> rules with bytes=268435456 count=0. Now grace=26843545
>> doveadm(<user>): Debug: Namespace INBOX.: Using permissions from
>> /home/.../test: mode=0700 gid=default
>>
>> $ cat maildirsize
>> 268435456S
>> 29394 34
>>
>>
>> So the used quota has exactly been doubled by just creating an empty
>> subfolder.
>>
>> Do you have any pointers for fixing my configuration or is this a bug in
>> dovecot?
>>
>>
> I coincidentally resurrected a months-old thread with this same issue a
> few days ago. I'm seeing the exact same after upgrading from 2.2.32 to
> 2.2.36.
>
> The original poster (who also narrowed it down to something in 2.2.34)
> mentioned a workaround that does indeed work, namely setting
> mailbox_list_index=no:
>
> > doveadm -o 'mailbox_list_index=no' quota recalc -u myuser
>
> I've been staring at diffs of 2.2.33 and 2.2.34 without anything jumping
> out at me (not a C guy, sadly). Maybe src/lib-storage/index/index-storage.c
> or src/lib-storage/list/mailbox-list-fs-iter.c or
> src/lib-storage/list/mailbox-list-index-iter.c
> or src/lib-storage/list/mailbox-list-index.c?
>
> The latter few have some added strcmp's against "INBOX". Then again,
> there's a lot of new code in the diffs under src/lib-storage that
> references INBOX specifically.
>

Can the Dovecot team confirm whether this is indeed a bug or not?  I've not
yet been able to test 2.3.x to see if the problem exists there as well.
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