Re: [RFC][PATCH] uapi: Remove the inclusion of linux/mount.h from uapi/linux/fs.h

* David Howells:

We're seeing issues in autofs and xfstests whereby linux/mount.h (the UAPI
version) as included indirectly by linux/fs.h is conflicting with
sys/mount.h (there's a struct and an enum).

Would it be possible to just remove the #include from linux/fs.h (as patch
below) and rely on those hopefully few things that need mount flags that don't
use the glibc header for them working around it by configuration?

Wasn't <linux/mount.h> split from <linux/fs.h> relatively recently, and
userspace is probably using <linux/fs.h> to get the mount flag
definitions?

In retrospect, it would have been better to add the new fsmount stuff to
a separate header file, so that we could include that easily from
<sys/mount.h> on the glibc side.  Adhemerval posted a glibc patch to
fake that (for recent compilers):

  [PATCH] linux: Fix sys/mount.h usage with kernel headers
  <https://sourceware.org/pipermail/libc-alpha/2022-August/141316.html>

I think it should work reliably, so that's probably the direction we are
going to move in.

We'll backport this to 2.36, and distributions will pick it up.

Thanks,
Florian