Bug with mount.cifs and mapchars

[Tyler Spivey <tspivey8@gmail.com>]

Hi.

Note: I'm not subscribed, please CC.

I'm trying to mount a Windows 10 share from Linux with mapchars,
but it still uses the SFM mapping.

Linux storage 5.15.0-72-generic #79-Ubuntu SMP Wed Apr 19 08:22:18 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
mount.cifs version: 6.14
Command line: mount //192.168.145.1/e e -o username=tyler,uid=tyler,mapchars

This also failed under Arch:

Linux arch1 6.3.3-arch1-1 #1 SMP PREEMPT_DYNAMIC Sun, 21 May 2023 16:15:22 +0000 x86_64 GNU/Linux
mount.cifs version: 7.0

If I create a file called test? in a directory, the ?
shows up on the Windows machine as u+f025 (SFM mapping).
With mapchars, I would expect u+f03f (SFU mapping).

Looking at the kernel source for version 6.3.3,
it looks like sfu_remap needs to be set for this to work.
However, I can't find anything which sets it (mapchars doesn't seem to
be hooked up to it).

Thanks,
Tyler