Re: Does linux smb2 client supports DFS capability?

Re: Does linux smb2 client supports DFS capability?

[Steve French]

If you are checking if the SMB3 DFS enablement has been added to your
kernel (if your kernel is older than version 4.11), you could look to
see if the equivalent of this patch (it is part of a small series of
DFS related patches, but would be one of the more visible ones in the
series)

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/cifs?id=9d49640a21bffd730a6ebf2a0032e022f7caf84a


On Wed, Oct 11, 2017 at 6:47 AM, Aurélien Aptel <aaptel-IBi9RG/b67k@public.gmane.org> wrote:
> Hi,
>
> Hemanth Thummala <hemanth.thummala-8cO4VLV/4DJBDgjK7y7TUQ@public.gmane.org> writes:
>> If so, Can you please let me know (or point me a link) the version of cifs-utils in which support is available.
>> I have tested with cifs-util-6.2 version. This doesn’t have the DFS support.
>
> cifs-util only contains the source code of the the mount.cifs program,
> which doesn't do much. The SMB client code lives in the cifs kernel
> module. To use DFS with SMB2 you need to use linux kernel v4.11 or
> newer.
>
> Cheers,
>
> --
> Aurélien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
> GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)



-- 
Thanks,

Steve

Re: Does linux smb2 client supports DFS capability?

[Richard Sharpe]

On Wed, Oct 11, 2017 at 7:25 AM, Steve French <smfrench-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> If you are checking if the SMB3 DFS enablement has been added to your
> kernel (if your kernel is older than version 4.11), you could look to
> see if the equivalent of this patch (it is part of a small series of
> DFS related patches, but would be one of the more visible ones in the
> series)
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/cifs?id=9d49640a21bffd730a6ebf2a0032e022f7caf84a
>
>
> On Wed, Oct 11, 2017 at 6:47 AM, Aurélien Aptel <aaptel-IBi9RG/b67k@public.gmane.org> wrote:
>> Hi,
>>
>> Hemanth Thummala <hemanth.thummala-8cO4VLV/4DJBDgjK7y7TUQ@public.gmane.org> writes:
>>> If so, Can you please let me know (or point me a link) the version of cifs-utils in which support is available.
>>> I have tested with cifs-util-6.2 version. This doesn’t have the DFS support.
>>
>> cifs-util only contains the source code of the the mount.cifs program,
>> which doesn't do much. The SMB client code lives in the cifs kernel
>> module. To use DFS with SMB2 you need to use linux kernel v4.11 or
>> newer.
>>
>> Cheers,

I think their real interest is in the CIFS FS getting DFS referrals if
STATUS_PATH_NOT_COVERED is returned on a CREATE.

When I last looked the client could not do that.

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)

Re: Does linux smb2 client supports DFS capability?

[Aurélien Aptel]

Richard Sharpe <realrichardsharpe-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
> I think their real interest is in the CIFS FS getting DFS referrals if
> STATUS_PATH_NOT_COVERED is returned on a CREATE.
>
> When I last looked the client could not do that.

cifs.ko should be able to traverse a DFS link on the FS, after the DFS
mounted. My testing setup when I worked on this was the following:

//A/root
       |
       +- link -> //B/target
       +- sublink -> //B/target/sub

//B/target
       |
       + sub/
          |
          + dir/
              |
              + files..

And I had a script
- mounting //A/root and running cd&ls in /, /link, /link/sub,
  /link/sub/dir, /sublink, /sublink/dir
- mounting //A/root/link and running cd&ls in /, /sub, /sub/dir
- mounting //A/root/link/sub and running cd&ls in /, /dir
- mounting //A/root/sublink and running cd&ls in /, /dir
- mounting //A/root/sublink/dir and running cd&ls in /

And all worked for vers={1.0,3.0}, A being {samba, Windows Server 2016},
B being {samba, Windows Server 2012 R2} when I submitted the patches.

-- 
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)