[Dovecot] dovecot + virtio (9p2000.L) = errors

[epek at gmx.net]

Hi!
I hope someone knows more about the issues I've encountered in:
 
Setup:
I am running dovecot 2.1.7 on Debian Wheezy in a virtual machine (kvm-style qemu-kvm: host: ubuntu 13.04/1.4.0-dfsg-1expubuntu). The mail storage is a directory on the host machine mounted via virtfs (9p2000.L)  on the guest. Furthermore ISPConfig is involved in that setup, but that should not make any significant difference at that point.
 
Problem resolved:
The problem is, that similar to nfs mmap() and dotlocking seem to fail - the mmap issue could be resolved by adding:
mmap_disable=yes
to dovecot.conf
 
Problem remaining:
Still the following errors remain, despite dotlock_use_excl=no
 
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/.quotausage.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: file dict commit: file_dotlock_open(/var/vmail/mydomain/test/.quotausage) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:51 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:52 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:52 host dovecot: imap(test at mydomain): Error: file_dotlock_create(/var/vmail/mydomain/test/Maildir/dovecot-uidlist) failed: No such file or directory
May 27 12:54:52 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:52 host dovecot: imap(test at mydomain): Error: fstat(/var/vmail/mydomain/test/Maildir/dovecot-uidlist.lock) failed: No such file or directory
May 27 12:54:52 host dovecot: imap(test at mydomain): Error: file_dotlock_create(/var/vmail/mydomain/test/Maildir/dovecot-uidlist) failed: No such file or directory
 
The "failed" files are existing on that path - permissions for the configured "vmail" user and group exist (0600).
 
I'd be greatful for any hint on how to resolve that issue - Thanks in advance!
 
Regards
Erich