[Dovecot] Index cache errors worse with 2.2.x

[Alexander 'Leo' Bergolth]

Hi!

I am getting "Cached message size smaller than expected" errors since dovecot-2.1.x.
Until now, I thought that those errors don't do any harm, I assumed that the cache will just be rebuilt after the error had been detected.

However, since dovecot 2.2.x (I tried 2.2.7 and 2.2.10), the errors sometimes seem to actually cause mail access to fail.

With dovecot-2.1.1, only the first two messages were logged, since using 2.2.7 and 2.2.10, the "read ... failed: Invalid argument" sometimes appear:
-------------------- 8< --------------------
May  7 17:03:52 samba dovecot: imap(xyz): Error: Cached message size smaller than expected (2246 < 2247)
May  7 17:03:52 samba dovecot: imap(xyz): Error: Corrupted index cache file /home/xyz/mail/.imap/INBOX/dovecot.index.cache: Broken physical size for mail UID 11277
May  7 17:03:52 samba dovecot: imap(xyz): Error: read(/var/mail/xyz) failed: Invalid argument
May  7 17:03:52 samba dovecot: imap(xyz): Error: read(/var/mail/xyz) failed: Invalid argument (uid=11277)
-------------------- 8< --------------------

I am using dovecot on RHEL6 with mbox mailboxes. Message size differences are always 1 byte.

Any hints would be appreciated!

Cheers,
--leo

P.S.: Those errors occur some times a day and affect different users..
(Upgrade 2.1.1 -> 2.2.7 was on 2013-11-22, 2.2.10 was installed on 2014-01-20.)

# for f in maillog* ; do echo -n "$f: "; grep "dovecot:.*Error: read.*failed.*Invalid arg" $f | wc -l; done
maillog: 31
maillog-20130801: 0
maillog-20130901: 1
maillog-20131001: 0
maillog-20131101: 0
maillog-20131201: 30
maillog-20140101: 92
maillog-20140201: 110
maillog-20140301: 99
maillog-20140401: 133
maillog-20140501: 100

# for f in maillog* ; do echo -n "$f: "; grep "dovecot:.*Error: Cached message size smaller than expected" $f | wc -l; done
maillog: 99
maillog-20130801: 465
maillog-20130901: 484
maillog-20131001: 512
maillog-20131101: 460
maillog-20131201: 520
maillog-20140101: 402
maillog-20140201: 400
maillog-20140301: 355
maillog-20140401: 481
maillog-20140501: 434

-- 
e-mail   ::: Leo.Bergolth (at) wu.ac.at
fax      ::: +43-1-31336-906050
location ::: IT-Services | Vienna University of Economics | Austria