[Samba] Overwriting open files on cifs mount of Samba share fails

[Jeremy Allison]

On Fri, Nov 05, 2021 at 08:14:02PM +0100, Philipp Wendler via samba wrote:
>I have tested this among others with Ubuntu 20.04 on both client and
>server (kernel 5.4.0 and samba 4.11.6). I am aware that these are not
>the latest versions, but as mentioned would greatly appreciate any
>information about whether an update could potentially improve the
>situation.
>My configuration is totally standard as I tested it with a fresh
>installation and just added a writable share.
>The resulting mount options on the client are
>rw,relatime,vers=3.1.1,cache=strict,uid=1000,noforceuid,gid=1000,noforcegid,
>file_mode=0755,dir_mode=0755,soft,nounix,serverino,mapposix,
>rsize=4194304,wsize=4194304,bsize=1048576,echo_interval=60,actimeo=1
>Of these, I only specified vers, uid and gid.
>nounix was automatically added although testparm -v on the server says
>"unix extensions = Yes".

"unix extensions" only works over SMB1 at the moment. You
have specified SMB version 3.1.1 in your mount options on
the client, plus friends don't let friends use SMB1 anymore
(and your server almost certainly has SMB1 disabled).

The client redirector will have to try and spoof this,
rename over open files can't be done with "standard"
SMB2+.