samba - Jul 2015 - Constant error messages about failure to remove oplock

On Thu, Jul 09, 2015 at 10:39:58AM +0530, Shyam Kaushik
wrote:
> Hi All,
> 
> Need your help/inputs on what could be the probable cause/how to debug
> this further.
> 
> We are using samba-4.0.25 & expose a share that has oplocks enabled
& no
> kernel-oplocks set. We constantly see these messages in samba logs
> 
> 	[2015/06/25 03:05:30.593150,  0, pid=1581, class=locking]
> ../source3/smbd/oplock_linux.c:184(linux_release_kernel_oplock)
> 	  linux_release_kernel_oplock: Error when removing kernel oplock
> on file ~test.pst.tmp, file_id = 10fcbd:4a9ff1c:0, gen_id = 3680654993.
> Error was Resource temporarily unavailable
Do you have "kernel oplocks = no" set? Then this is
surprising to see. If you can reproduce it, can you send the
output of

strace -ttT -p <smbd-pid> 

for such an smbd from before opening the file to the error?

Thanks,

Volker Lendecke

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de

On Thu, Jul 09, 2015 at 01:09:05PM +0530, Shyam Kaushik
wrote:
> Hi Volker,
> 
> Yes this problem happens when we have "kernel oplocks = no". This
happened
> constantly in one of production systems & so we disabled level2-oplock
> /set kernel-oplocks=yes (to avoid this issue). So unfortunately don’t have
> an environment where it reproduces now & cannot capture strace.
> 
> I modified smbtorture/smb2 to do a test exactly like the tcpdump trace,
> but the problem doesn’t happen. One thing is we don’t have session
> create/tree-connect captured for the below problematic case. Do you think
> it can have any influence on this (like varied parameters negotiated at
> session establish)?
> 
> Also one difference b/n the smbtorture/smb2 test that I wrote is, in the
> tcpdump I see that when the original problem happened, in SMB2/create
> response, samba returned allocation-size=1MB whereas in my test, this is
> not returned. I am not sure how this can happen as SMB2 create request in
> tcpdump has
> 	ExtraInfo DHnQ MxAc QFid
> (i.e. no ALSI specified in it). Any thoughts?
> 
> Thanks for your inputs!
No, sorry, not really. If I had a reproducer I'd probably
very quickly be able to see what's going on. The things I'd
look at are the debug level 10 log together with the strace.

With best regards,

Volker

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de