[Dovecot] Shared folder (namespace) access hanging

[Jeff Turner]

Hi,

I'm using Dovecot 1.0-b8. We use a shared 'support' account for incoming
support mail. For security reasons we want to instead have everyone with their
own account, accessing a shared 'support' folder. So I've configured dovecot
with a public 'Support' namespace:

default_mail_env = maildir:/imap/mailboxes/%u

namespace private {
   separator = /
   prefix = 
   inbox = yes
}
namespace public {
    separator = /
    location =
    maildir:/imap/mailboxes/support:CONTROL=/imap/mailboxes/%u/shared-settings/support/control
    prefix = Support/
    hidden = no
}

So now:
 - User 'support' logs in (this is the user whose folder is being
   shared). Dovecot creates a dovecot-uidlist file:

root at redback:/imap/mailboxes/support/.INBOX.test# cat dovecot-uidlist 
1 1147757548 9
1 1147755677.P8078Q3M183587.redback.sydney.atlassian.com:2,RSace
2 1147755677.P8078Q2M183587.redback.sydney.atlassian.com:2,abcdf
3 1147755677.P8078Q1M183587.redback.sydney.atlassian.com:2,Sabcd
4 1147756077.P8078Q8.redback.sydney.atlassian.com:2,Sabcd
5 1147756440.P8461Q3M643698.redback.sydney.atlassian.com:2,Sa
6 1147756440.P8461Q2M643698.redback.sydney.atlassian.com:2,Sa
7 1147756440.P8461Q1M643698.redback.sydney.atlassian.com:2,Sa
8 1147756440.P8461Q0M643698.redback.sydney.atlassian.com:2,Sa
root at redback:/imap/mailboxes/support/.INBOX.test# ls -la
total 60
drwxrwx---    5 jturner  mail         4096 May 16 15:32 .
drwxrwxrwx   59 support mail         4096 May 16 15:31 ..
drwxrwx---    2 jturner  mail         4096 May 16 15:18 cur
-rw-rw-rw-    1 support mail          448 May 16 15:32 dovecot.index
-rw-rw-rw-    1 support mail        21504 May 16 15:32 dovecot.index.cache
-rw-rw-rw-    1 support mail          512 May 16 15:32 dovecot.index.log
-rw-------    1 support mail           72 May 16 15:28 dovecot-keywords
-rw-rw-rw-    1 jturner  mail            0 May 16 14:52 dovecot-shared
-rw-rw-rw-    1 support mail          516 May 16 15:32 dovecot-uidlist
drwxrwx---    2 jturner  mail         4096 May 16 15:01 new
drwxrwx---    2 jturner  mail         4096 May 16 15:14 tmp
root at redback:/imap/mailboxes/support/.INBOX.test# 

 - If I now log in as 'jturner' and subscribe to this folder, there
   appears to be nothing in the 'test' folder. On disk, the folder
subscription is registered but the test folder's CONTROL directory is
empty:

# ls /imap/mailboxes/jturner/shared-settings/support/control/
subscriptions
# cat /imap/mailboxes/jturner/shared-settings/support/control/subscriptions 
INBOX.test
# ls /imap/mailboxes/jturner/shared-settings/support/control/.INBOX.test/
#

Restarting dovecot and Thunderbird makes no difference.


However, if I delete dovecot.index and dovecot.index.log from
/imap/mailboxes/support/.INBOX.test/, then suddenly it works.  User
'jturner' can view the folder contents, and a uidlist file for them
appears:

# cat /imap/mailboxes/jturner/shared-settings/support/control/.INBOX.test/dovecot-uidlist 
1 1147758095 9
1 1147755677.P8078Q3M183587.redback.sydney.atlassian.com:2,RSace
2 1147755677.P8078Q2M183587.redback.sydney.atlassian.com:2,abcdf
3 1147755677.P8078Q1M183587.redback.sydney.atlassian.com:2,Sabcd
4 1147756077.P8078Q8.redback.sydney.atlassian.com:2,Sabcd
5 1147756440.P8461Q3M643698.redback.sydney.atlassian.com:2,Sa
6 1147756440.P8461Q2M643698.redback.sydney.atlassian.com:2,Sa
7 1147756440.P8461Q1M643698.redback.sydney.atlassian.com:2,Sa
8 1147756440.P8461Q0M643698.redback.sydney.atlassian.com:2,Sa

Although the contents is the same (1-8), the UIDVALIDITY at the top is
different to that for the 'support' user:

# head -1 /imap/mailboxes/jturner/shared-settings/support/control/.INBOX.test/dovecot-uidlist 
1 1147758095 9
# head -1 /imap/mailboxes/support/.INBOX.test/dovecot-uidlist 
1 1147757548 9

and now if I log back in as 'support' and access the folder, dovecot
complains:

dovecot: May 16 15:47:05 Error: IMAP(support): Corrupted index cache file /imap/mailboxes/support/.INBOX.test/dovecot.index.cache: indexid changed

Switching back and forth results in various errors:

dovecot: May 16 15:48:04 Error: IMAP(support): Corrupted transaction log file /imap/mailboxes/support/.INBOX.test/dovecot.index.log: end_offset (656) > current sync_offset (512)
dovecot: May 16 15:48:04 Error: IMAP(support): Corrupted transaction log file /imap/mailboxes/support/.INBOX.test/dovecot.index.log: invalid indexid (1147758095 != 1147757548)
dovecot: May 16 15:48:04 Error: IMAP(support): Corrupted transaction log file /imap/mailboxes/support/.INBOX.test/dovecot.index.log: invalid new transaction log sequence (2 >= 2)
dovecot: May 16 15:48:04 Error: IMAP(support): Lost transaction log file /imap/mailboxes/support/.INBOX.test/dovecot.index.log seq 1


------------------------------

In the wild, I've seen frequent occurrences of this error, where dovecot
seems to switch between the UIDVALIDITY of 'support' and a user's
dovecot-uidlists:

dovecot: May 16 13:56:28 Error: IMAP(jturner): Maildir /imap/mailboxes/support/.INBOX sync: UIDVALIDITY changed (1147751603 -> 1147686345)

and here's it toggling back from 'support' to jturner's dovecot-uidlist
uidvalidity:

dovecot: May 16 14:16:04 Error: IMAP(support): Maildir /imap/mailboxes/support/.INBOX sync: UIDVALIDITY changed (1147752716 -> 1147751603)


I've also seen plenty of processes being killed, seemingly at random,
about 3 or 4 a minute:

# cat /usr/local/logs/dovecot | grep killed.wit
...
dovecot: May 16 12:00:16 Error: child 32706 (imap) killed with signal 6
dovecot: May 16 12:00:16 Error: child 32649 (imap) killed with signal 14
dovecot: May 16 12:00:45 Error: child 32412 (imap) killed with signal 6
dovecot: May 16 12:01:02 Error: child 32702 (imap) killed with signal 6
dovecot: May 16 12:01:02 Error: child 368 (imap) killed with signal 6
dovecot: May 16 12:01:02 Error: child 357 (imap) killed with signal 6
dovecot: May 16 12:01:16 Error: child 383 (imap) killed with signal 6
dovecot: May 16 12:02:26 Error: child 32297 (imap) killed with signal 6
...


So I'm confused. Am I doing something stupid? Why is there a common
.cache file (it doesn't get created in the CONTROL dir), but not a common
dovecot-uidlists? Is anyone actually *using* shared folders? :)


Thanks,

Jeff