Re: util-linux 2.39 doesn't work with <linux-5.12: mount(2) system call failed: Function not implemented

[Thomas Deutschmann <whissi@whissi.de>]

Hi,

On 2023-05-22 09:43, Thomas Weißschuh wrote:
> I was finally able to reproduce the issue.
> 
> Could you test https://github.com/util-linux/util-linux/pull/2248 again?

This fixes the issue for me, thank you!

Just one comment regarding the design of the fix:

Due to the introduction of mount_setattr_is_supported(), util-linux will 
now "waste" one syscall on every mount -- even on a modern system -- right?

A more "natural" approach like calling new API first but when this will 
fail with ENOSYS then fallback to old API (so we would only spend an 
additional call on old systems which is fine because we assume that 
their number will decrease over time) cannot be implemented due to the 
way how the hook system works, right?

But maybe this "wasted" call isn't much to think about. I was just 
wondering when I saw a call like

   mount_setattr(-1, NULL, 0, NULL, 0)

even on modern systems.


-- 
Regards,
Thomas