samba - Oct 2019 - How to turn on SMB3 POSIX extensions in Samba server?

Hi, I want to use the SMB3 POSIX extensions in the latest Samba (with
SMB3.1.1, vers=3.1.1). By following the user manual, I have added the
"posix" mount option when mounting, but it shows the following error
messages.

Error messages:
[xxxxx] CIFS VFS: Server does not support mounting with posix SMB3.11
extensions.
[xxxxx] CIFS VFS: cifs_mount failed w/return code = -95

Mount option:
https://www.mankier.com/8/mount.cifs#posix%7Cunix%7Clinux
https://wiki.samba.org/index.php/SMB3-Linux

Mount commands:
mount ?t cifs -o username=<user>,vers=3.1.1,posix //<address>/share
/mnt/share
mount ?t cifs -o username=<user>,vers=3.1.1,posix,mfsymlinks
//<address>/share /mnt/share

Software and kernel version:
1. Ubuntu 19.04, Kernel 5.0, Samba 4.10
2. Ubuntu 18.04.3, Kernel 5.0, Samba 4.7

How to turn on SMB3 POSIX extensions in Samba server?

Thanks.

On 05/10/2019 06:49, Chris Han via samba wrote:
> Hi, I want to use the SMB3 POSIX extensions in the latest Samba (with
> SMB3.1.1, vers=3.1.1). By following the user manual, I have added the
> "posix" mount option when mounting, but it shows the following
error
> messages.
>
> Error messages:
> [xxxxx] CIFS VFS: Server does not support mounting with posix SMB3.11
> extensions.
> [xxxxx] CIFS VFS: cifs_mount failed w/return code = -95
>
> Mount option:
> https://www.mankier.com/8/mount.cifs#posix%7Cunix%7Clinux
> https://wiki.samba.org/index.php/SMB3-Linux
>
> Mount commands:
> mount ?t cifs -o username=<user>,vers=3.1.1,posix
//<address>/share
> /mnt/share
> mount ?t cifs -o username=<user>,vers=3.1.1,posix,mfsymlinks
> //<address>/share /mnt/share
>
> Software and kernel version:
> 1. Ubuntu 19.04, Kernel 5.0, Samba 4.10
> 2. Ubuntu 18.04.3, Kernel 5.0, Samba 4.7
>
> How to turn on SMB3 POSIX extensions in Samba server?
>
> Thanks.
Ah, sorry, but as far as I am aware, that manpage is wrong, it should say:

posix|unix|linux

 ??? (default) Enable Unix Extensions for this mount. Requires CIFS 
(vers=1.0) and a server supporting them.

There are no Unix extensions for SMBv2 or SMBv3 (yet)

Rowland

The SMB3 POSIX extensions is different from the old Unix extensions. The
Unix extensions can only support vers=1.0, but the new SMB3 POSIX
extensions can support SMB3.1.1, vers=3.1.1.

You can check this 2018 presentation slides:
https://www.snia.org/sites/default/files/SDC/2018/presentations/SMB/Steve_French_SMB311.pdf

Page 12 shows that POSIX extensions has been added.
Page 22 shows that SMB3 POSIX extensions has been added since Kernel 4.18.
Page 46 shows an example of mounting the Samba share using the mount option
"vers=3.1.1,posix"


On Sat, Oct 5, 2019 at 3:45 PM Rowland penny via samba <
samba at lists.samba.org> wrote:
> On 05/10/2019 06:49, Chris Han via samba wrote:
> > Hi, I want to use the SMB3 POSIX extensions in the latest Samba (with
> > SMB3.1.1, vers=3.1.1). By following the user manual, I have added the
> > "posix" mount option when mounting, but it shows the
following error
> > messages.
> >
> > Error messages:
> > [xxxxx] CIFS VFS: Server does not support mounting with posix SMB3.11
> > extensions.
> > [xxxxx] CIFS VFS: cifs_mount failed w/return code = -95
> >
> > Mount option:
> > https://www.mankier.com/8/mount.cifs#posix%7Cunix%7Clinux
> > https://wiki.samba.org/index.php/SMB3-Linux
> >
> > Mount commands:
> > mount ?t cifs -o username=<user>,vers=3.1.1,posix
//<address>/share
> > /mnt/share
> > mount ?t cifs -o username=<user>,vers=3.1.1,posix,mfsymlinks
> > //<address>/share /mnt/share
> >
> > Software and kernel version:
> > 1. Ubuntu 19.04, Kernel 5.0, Samba 4.10
> > 2. Ubuntu 18.04.3, Kernel 5.0, Samba 4.7
> >
> > How to turn on SMB3 POSIX extensions in Samba server?
> >
> > Thanks.
>
> Ah, sorry, but as far as I am aware, that manpage is wrong, it should say:
>
> posix|unix|linux
>
>      (default) Enable Unix Extensions for this mount. Requires CIFS
> (vers=1.0) and a server supporting them.
>
> There are no Unix extensions for SMBv2 or SMBv3 (yet)
>
> Rowland
>
>
>
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>

On 07/10/2019 08:46, Aur?lien Aptel wrote:
> The posix extensions are still a WIP unfortunately and do no ship with
> samba.
>
> In order to use the posix mount option you need a special build of samba
> from Jeremy's code [1]. This is documented in [2].
>
> 1:
https://git.samba.org/?p=jra/samba/.git;a=shortlog;h=refs/heads/master-smb2
> 2: https://wiki.samba.org/index.php/SMB3-Linux
>
> Cheers,
Jeremy has (as I hoped he would) already told him this over on the 
samba-technical list, he didn't seem to want to believe me ;-)

Rowland