dovecot - May 2007 - maildir_file_do(/var/admhome/user/Maildir) racing

dovecot version 1.0.0, compile from the sources.

--------- snip --------
# /usr/local/etc/dovecot.conf
listen: *:10143
ssl_listen: *:10943
ssl_cert_file: /etc/ssl/certs/postamt.pem
ssl_key_file: /etc/ssl/private/postamt.key
disable_plaintext_auth: no
login_dir: /usr/local/var/run/dovecot/login
login_executable: /usr/local/libexec/dovecot/imap-login
mail_location: maildir:~/Maildir
mail_plugins: quota imap_quota
namespace:
  type: private
  separator: .
  prefix: INBOX.
  inbox: yes
auth default:
  passdb:
    driver: pam
  userdb:
    driver: passwd
plugin:
  quota: maildir
  quota: maildir:ignore=Trash
--------- snip --------

We're using these odd ports, because there's still courier-imap on the
original ports.

One, just one (!) of our users gets:

May 14 16:47:17 postamt dovecot: imap-login: Login: user=<username>,
method=PLAIN, rip=141.42.x.y, lip=ip.of.the.server
May 14 16:47:17 postamt dovecot: imap-login: Login: user=<username>,
method=PLAIN, rip=141.42.x.y, lip=ip.of.the.server
May 14 16:47:17 postamt dovecot: IMAP(username):
maildir_file_do(/var/admhome/username/Maildir) racing
May 14 16:47:17 postamt dovecot: IMAP(username): Disconnected: Internal error
occurred. Refer to server log for more information. [2007-05-14 16:47:17]

Now it's a bit hard for me to see what's going on.
/var/admhome/username/Maildir is on /, thus:

$ mount
/dev/cciss/c0d0p6 on / type ext3 (rw,errors=panic)

$ dmesg
does not complain about any corruption

$ uname -a
Linux postamt.charite.de 2.6.21.1 #1 SMP Tue May 1 15:50:11 CEST 2007 i686
GNU/Linux

OS: Debian testing

-- 
Ralf Hildebrandt (i.A. des IT-Zentrums)         Ralf.Hildebrandt at charite.de
Charite - Universit?tsmedizin Berlin            Tel.  +49 (0)30-450 570-155
Gemeinsame Einrichtung von FU- und HU-Berlin    Fax.  +49 (0)30-450 570-962
IT-Zentrum Standort CBF                    send no mail to plonk at charite.de

On 14.5.2007, at 17.54, Ralf Hildebrandt wrote:
> One, just one (!) of our users gets:
>
> May 14 16:47:17 postamt dovecot: imap-login: Login:  
> user=<username>, method=PLAIN, rip=141.42.x.y, lip=ip.of.the.server
> May 14 16:47:17 postamt dovecot: imap-login: Login:  
> user=<username>, method=PLAIN, rip=141.42.x.y, lip=ip.of.the.server
> May 14 16:47:17 postamt dovecot: IMAP(username): maildir_file_do(/ 
> var/admhome/username/Maildir) racing
This happens at every login? I thought I'd never see this racing  
error. It means that Dovecot tried to some operation to a maildir  
file. But the operation failed, because the file was just renamed  
(eg. flag changed). So it located the file again, and found it. Then  
it tried the operation again, but it failed the same way. This was  
tried 10 times until it gave this "racing" error.

I think it's a bit unlikely that the filename was changing that fast.  
So there's probably a bug somewhere.. Could get strace output from  
those two logins and send them to me? You can do this with eg.:

mail_executable = /usr/local/bin/run-imap.sh

run-imap.sh:

#!/bin/sh
exec strace -tt -s 1000 -o /tmp/imap.$USER.`time +%u`.$$.log /usr/ 
local/libexec/dovecot/imap

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* Timo Sirainen <tss at iki.fi>:
> This happens at every login? I thought I'd never see this racing  
> error.
I found the reason:

The User had a symlink in his $HOME/Maildir/cur, which pointed to a
NON-existing file :(

Courier-IMAP ignored that, dovecot bailed out.

I removed the bogus symlink and all is well now.
> It means that Dovecot tried to some operation to a maildir  
> file.
Yep.

-- 
Ralf Hildebrandt (i.A. des IT-Zentrums)         Ralf.Hildebrandt at charite.de
Charite - Universit?tsmedizin Berlin            Tel.  +49 (0)30-450 570-155
Gemeinsame Einrichtung von FU- und HU-Berlin    Fax.  +49 (0)30-450 570-962
IT-Zentrum Standort CBF                    send no mail to plonk at charite.de