Errors with count:User quota and NFS

[Tom Sommer]

I upgraded to 2.2.26.0 and enabled count as quota backend, expecting the 
recent fixes to allow me to use the backend, however I get the following 
errors:

Oct 31 10:52:13 imap(xxxx at xxxx.xx): Error: Transaction log file 
/mnt/nfs/xxxx.xx/xxx/indexes/dovecot.list.index.log: marked corrupted
Oct 31 10:52:15 imap(xxx at xxxx.xx): Error: Transaction log file 
/mnt/nfs/xxxx.xx/xxx/indexes/dovecot.list.index.log: marked corrupted
Oct 31 10:52:37 imap(xxx at xxxx.xx): Warning: Locking transaction log file 
/mnt/nfs/xxx.xx/xxx/indexes/dovecot.list.index.log took 31 seconds 
(syncing)
Oct 31 10:52:37 imap(xxx at xxx.xx): Warning: Locking transaction log file 
/mnt/nfs/xxx.xx/xxx/indexes/dovecot.list.index.log took 31 seconds 
(syncing)
Oct 31 10:52:43 imap(xxx at xxx.xx): Error: Transaction log file 
/mnt/nfs/xxx.xx/xx/indexes/dovecot.list.index.log: marked corrupted
Oct 31 10:52:52 imap(xxx at xxx.xx): Warning: Locking transaction log file 
/mnt/nfs/xxx.xx/xxx/indexes/dovecot.list.index.log took 31 seconds 
(syncing)
Oct 31 10:53:04 imap(xxx at xxx.x): Warning: Locking transaction log file 
/mnt/nfs/xxx.xx/xxx/indexes/dovecot.list.index.log took 60 seconds 
(syncing)
Oct 31 10:53:06 imap(xxx at xxx.xx): Warning: Locking transaction log file 
/mnt/nfs/xxx.xxx/xxx/indexes/dovecot.list.index.log took 31 seconds 
(syncing)

(all different accounts)

If I disable count as backend, there are no errors.

I'm running my mail-storage on NFS, so I suspect the errors are due to 
locking? So is there no way to run count as quota backend with NFS?

Thanks.
-- 
Tom