[Samba] Change in mount behavior of the CIFS module from Debian kernel 6.12 to 6.16

[Rowland Penny]

On Wed, 19 Nov 2025 14:42:27 +0100
Peter Milesson via samba <samba at lists.samba.org> wrote:

> Hi folks,
> 
> I got a seriously unpleasant problem, when LXDE stopped working in a 
> bunch of terminals after kernel upgrade from 6.12.48 to 6.16.3. There 
> were no indications about errors in the log files, so tracking down
> the bug was very hard. The only find was a couple of errors in the 
> ~/.xsession-errors file. The error was basically that ssh-agent could 
> not bind to sockets in the ~/.ssh/agent directory, as they were
> missing.
> 
> I'm mounting the user's folder under /home from a CIFS server with 
> pam-mount after successful authentication. The mount parameters were:
> 
> dir_mode=0700,nosuid,nodev,sec=krb5i,cruid=<userid>,mfsymlinks,nobrl,vers=3.0
> 
> Using kernel 6.16.3, the sshd-agent could not create sockets in the 
> ~/.ssh/agent directory. That worked with kernel 6.12.48, and LXDE was 
> happy. I read through the CIFS documentation and found that the 
> parameter sfu had any relevance. I replaced mfsymlinks with sfu so
> the parameters sent to cifs mount were:
> 
> dir_mode=0700,nosuid,nodev,sec=krb5i,cruid=<userid>,sfu,nobrl,vers=3.0
> 
> After this change, sockets were created, and LXDE started on the
> terminal.
> 
> Please, could somebody who knows explain to me, if the change in 
> mfsymlinks behavior was intentional, or if it is a bug? Is the sfu 
> parameter expected to stay for the foreseeable future, or will that
> also be changed or removed? Are there any alternatives to mfsymlinks
> and sfu?
> 
> Best regards,
> 
> Peter

I have no idea about this, but feel you stand more chance of getting a
response on this if you post to the samba-technical list, that may
attract the attention of Steve French (the 'f' in mfsymlinks).

Rowland