[Dovecot] mbox sync/lock issue, rc28 and later

[Jeff A. Earickson]

Help!

I just noticed this error this morning, we have been getting a
lot of these in rc28 and rc29, not in rc27 or before:

Apr  6 07:22:52 karst dovecot: [ID 107833 mail.error] IMAP(jaearick): mbox file /var/mail/j/jaearick was modified while we were syncing, check your locking settings

Pine coughed up an internal error, no core dump, and dovecot
basically doubled the size of my mailbox by duplicating all of
my messages again.  What changed with file locking between rc27 
and rc28 to cause this?  How to fix?

My setup: dovecot server is Solaris 10, with ZFS for home directories
(where index files go).  The mail server is also Solaris 10, /var/mail
NFS mounted to the dovecot server (NFSv4, yes lockd is running).  The
/var/mail filesystem on the mail server is also ZFS.

Here is the output of "dovecot -n":

# ./dovecot -n
# /opt/dovecot.1.0.rc29/etc/dovecot.conf
base_dir: /var/run/dovecot/
ssl_listen: *
ssl_cert_file: /opt/openssl/ssl/certs/colby0.cert
ssl_key_file: /opt/openssl/ssl/private/colby0.key.nopasswd
login_dir: /var/run/dovecot//login
login_executable: /opt/dovecot.1.0.rc29/libexec/dovecot/imap-login
login_process_per_connection: no
login_processes_count: 8
first_valid_uid: 100
first_valid_gid: 100
mail_location: mbox:%h/mail:INBOX=/var/mail/%1u/%u:INDEX=%h
mail_drop_priv_before_exec: yes
auth default:
   passdb:
     driver: passwd-file
     args: /etc/dovecot.deny
     deny: yes
   passdb:
     driver: pam
   userdb:
     driver: passwd

Jeff Earickson
Colby College