[Samba] Samba daemons hang trying to lock locking.tdb

[Fermin Molina]

Hi,

> On Tue, Jan 31, 2006 at 08:07:05PM +0100, Fermin Molina wrote:
> > Hi,
> > 
> > After upgrade to samba 3.0.21b, the behaviour is the same.
> > I think the problem must be related to TDB (Trivial DB) code. The call
> > fcntl64() is trying to lock for write the file /var/cache/locking.tdb,
> > but with the F_SETLKW file control command. This control command waits
> > if the file is blocked. If another process locks for write this file,
> > can we get a deadlock?
> 
> No, the fcntl locks are done to allow concurrent safe access
> to the tdb's. The only way you can get a deadlock is if there
> is a logic bug in the code, or if the underlying file system
> is hanging on granting a lock.


Ok, I see.


> /var/cache/locking.tdb is on a local filesystem on your
> machine, correct ?


Yes, it is. It's on a partition from a volume created on a Smart Array
controller.


> Oftentimes locks don't work correctly
> on remote mounted filesystems.
> 
> > The fact is that some hours after start samba, some smbd daemons hangs
> > waiting to get a write lock to locking.tdb file. The windows clients
> > associated with these smbd daemons get stalled and the user must to
> > reset the machine (or I kill -9 these daemons).
> > 
> > Any clue?
> 
> We need more information on how to reproduce this, it's not
> a generic logic bug I believe as it's not been widely reported.


Ok. I will try to reproduce it (well, get debug data when it occurs) and
I will send you. Only one question: what log level I need to configure
in order the debug info I get will be useful to you?

Thanks so much.

/Fermin