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

[Timo Sirainen]

On 6.4.2007, at 20.08, Jeff A. Earickson wrote:

>> But what do you mean duplicated the messages? Same messages exist  
>> multiple times in the mbox file? The only reason I can think of  
>> how that could happen is if you expunged a lot of data from the  
>> middle of the mbox, and then in the middle of the move that  
>> external modification check cancelled the sync.
>
> That seems to be what happened.  I had marked a bunch of messages  
> as deleted,
> and had done "expunge" in Pine to trash them.  Then pine gave its  
> internal
> error.  Afterwords, most of the deleted messages were gone, some at  
> the
> end were not (not marked as deleted), and about 20 messages in the  
> middle
> of the mailbox were duplicated again at the end.  I think a new  
> message came
> in too.  Except for the duplication and the undeletes, no messages  
> were
> mangled.  I just had to re-delete some messages.
>
> After this odd behavior, I went looking for a core file (none), and  
> I checked
> my syslogs.  That is when I found the pile of messages about  
> "modified while
> syncing".  I found this message 1161 times in my syslogs since  
> March 28, 50
> times today.  Nobody has complained about anything though.

I guess this has something to do with NFS attribute caching then. For  
now you could disable the check by changing  
mbox_sync_file_is_ext_modified() to just contain "return FALSE;" in  
mbox-sync.c.

Hmm. Wonder if I should add a new setting for this or just disable  
the check completely for v1.0.. The reason why I added it in the  
first place was because I wanted to know if some mbox problems were  
caused by locking problems or real bugs in Dovecot. If the settings  
are correct it's a bit useless to do this check.
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