Re: SMB3 Unix Extensions - creating special files

Hi,

Just got back to testing this and wondering if these patches made it into ML?

I've tested with 6.17 (Ubuntu Noble standard kernel) and latest 6.19 (mainline) and am seeing odd behaviour where it is creating regular files with 'special' metadata rather than 'real' special files. (This might be a different issue of course!). Reading existing special files (created on 'real' fs) works fine.

I'm basically using the same config as in my original post - server is running 4.23.6 with the following config:

[global]
    workgroup = WORKGROUP
    security = user
    map to guest = never
    log level = 3
    guest ok = no
    smb3 unix extensions = yes
    follow symlinks = yes


[myshare]
    path = /mnt/users
    browsable = yes
    writable = yes
    read only = no
    valid users = sambauser #uid/gid 1000
    create mask = 0777
    directory mask = 0777

Client is mounting as:

mount -t cifs //server.example.com/myshare /mnt/smb -o posix,vers=3.1.1,username=sambauser,pass=testing123

Reading existing special files created on real fs works fine:

> stat test_local

stat test_local
  File: test_local -> test.txt
  Size: 5               Blocks: 1          IO Block: 16384  symbolic link
Device: 0,49    Inode: 1099511631046  Links: 1

I can then do:

touch foo
ln -s foo foo_link

> stat foo_link
  File: foo_link -> mnt/smb/foo
  Size: 23              Blocks: 0          IO Block: 16384  symbolic link
Device: 0,48    Inode: 1099511629531  Links: 1

However on 'real' filesystem:
> stat foo_link
  File: foo_link
  Size: 0               Blocks: 0          IO Block: 4194304 regular empty file
Device: 3ch/60d Inode: 1099511629531  Links: 1

getfattr -d x_link
# file: x_link
user.DOSATTRIB=0sAAAFAAUAAAARAAAAIAQAAJmcGa5UqtwB
user.SmbReparse=0sDAAAoGgAAAAuAC4AAAAuAAAAAABvAHAAdAAvAGMAZQBwAGgALwBzAGMAcgBhAHQAYwBoAC8AdABlAHMAdAAvAHgAbwBwAHQALwBjAGUAcABoAC8AcwBjAHIAYQB0AGMAaAAvAHQAZQBzAHQALwB4AA==

Any suggestions appreciated as to what's going wrong - happy to provide network traces if that's needed.

Thanks,

Matthew


________________________________________
From: Paulo Alcantara <[email protected]>
Sent: 31 July 2025 21:00
To: Matthew Richardson; Steve French
Cc: Ralph Boehme; Samba Listing; CIFS
Subject: Re: [Samba] SMB3 Unix Extensions - creating special files

Matthew Richardson <[email protected]> writes:

> I've just tried the 6.16 kernel from mainline (Linux vm-b
> 6.16.0-061600-generic #202507272138 SMP PREEMPT_DYNAMIC Sun Jul 27
> 22:00:36 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux) and while mkfifo works
> again, ln -s is still giving 'operation not supported'.

Yes - mainline is still broken.  I'll send a fix soon to ML.
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