[Samba] Share mounts in SMBv1 mode, but fails weirdly in SMBv2 mode

Hadrien Grasland grasland at lal.in2p3.fr
Thu Oct 19 08:48:57 UTC 2017

So, as a follow-up on this, I also took this matter to the linux-cifs 
mailing list. After a bit of analysis, it turns out that...

 1. The Linux CIFS client was sending ill-formed QUERY_INFO packets to
    the server. There is a patch for this in the pipeline.
 2. There is also a bug in the server, which refuses to send all info
    about the root filesystem inode, in spite of knowing this info in
    principle. Considering that the bug is known and fixed upstream, and
    the problem is on our side (we cannot apply the server update for
    some unclear reason), it was decided not to work around it.

Thanks for your help in this investigation!
Hadrien Grasland

Le 13/10/2017 à 17:01, L.P.H. van Belle via samba a écrit :
>> -----Oorspronkelijk bericht-----
>> Van: samba [mailto:samba-bounces at lists.samba.org] Namens
>> Hadrien Grasland via samba
>> Verzonden: vrijdag 13 oktober 2017 15:34
>> Aan: samba at lists.samba.org
>> Onderwerp: Re: [Samba] Share mounts in SMBv1 mode, but fails
>> weirdly in SMBv2 mode
>> Hi Louis,
>> Thanks for your reply!
>>> This might be a kernel thing. 4.13.5-1 .. ? Archlinux?
>> OpenSUSE Tumbleweed, actually.
>> At some point, I got tired of rebuilding the entire world all
>> the time
>> because of the millenary tension between the wishes of stable distro
>> maintainers (who would rather not fix what isn't broken, and keep
>> packages as stable as possible) and those of my developer colleagues
>> (who would rather put hard requirements on GCC 7 or CMake 3.9
>> whenever
>> they can get away with it), and decided that I could live with the
>> occasional breakages of a rolling distro at work, as long as rolling
>> back a broken system was easy.
>>> There where recently e-mail about this on technical.
>>> So maybe its not implemented parts in samba or mount commands (yet)
>> I would welcome any clarification on this.
>>> And i point to this : smb2_get_dfs_refer
>>>>>>> [13424.783242] CIFS VFS: ioctl error in smb2_get_dfs_refer rc=-2
>>>>>>> [13424.789504] CIFS VFS: cifs_read_super: get root inode failed
>>> To give an idea..
>> https://kernel.opensuse.org/cgit/kernel-source/diff/patches.fi
>> xes/0001-CIFS-implement-get_dfs_refer-for-SMB2.patch?id=98a4a0
>> 402b8b564b24414c3f2d6b0268f6843341
>> I ended up on this kernel patch as well while googling the error,
>> however from a look at the code and the dmesg output, the
>> error seemed
>> to originate from an underlying call to the SMB2_ioctl() function.
>> Juding from the short name and the long list of parameters, this
>> function seemed like a big piece of machinery on its own, so
>> I decided
>> not to investigate it further without extra help. Which is
>> why I came here.
>>> This italian site shows exact the same problem.
>>> http://forum.html.it/forum/showthread/t-2959605.html
>>> I suggest, lower you kernel to 4.9 somewhere around there.
>>> See if that works, and then try vers=2.1
>> Rolling back the kernel this far may be a bit difficult on
>> Tumbleweed. I
>> never tried it, but the maintainers tend to be quite agressive at
>> removing old package versions from the repos. I guess that going for
>> older kernels is not true to their vision of the rolling
>> release spirit :)
>> As for version 2.1, I have tried it already, but unfortunately the
>> server does not seem to support it (dmesg gives a "Dialect
>> not supported
>> by server." error).
> Ah, wel at least that a better result, not what you want, but better.
>> Note that I am not in an immediate hurry to get SMBv2 working. SMBv1
>> works for me today, and from discussion with the sysadmins,
>> it will be a
>> long while before they disable it entirely. So I have time to
>> investigate this issue, file any needed bug report to the relevant
>> software projects, and would even help working on the fix myself if I
>> had even a remote idea of what's going on here. Sadly, my technical
>> background is more in scientific computing than distributed
>> filesystems.
>> By the way, if you could tell me a bit more about the relationship
>> between the kernel CIFS support and Samba, it might help. I
>> naively went
>> for the samba mailing list first as I got the impression that this is
>> the project where all Linux SMB protocol support is
>> implemented first,
>> but perhaps I should take this to the kernel mailing list(s) instead ?
> Phoe.. Good question. It never hurst to ask them also.
> I suggest, ask it on samba-technical, or wait a bit, often they look in the samba threah also.
>> Thanks for the help,
>> Hadrien
>>> Greetz,
>>> Louis

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