RFC: checking file systems support UF_HIDDEN, UF_SYSTEM

From: Rick Macklem <rick.macklem_at_gmail.com>
Date: Wed, 02 Jul 2025 21:02:14 UTC
Hi,

I am implementing the "hidden" and "system" attributes for
NFSv4 using UF_HIDDEN and UF_SYSTEM.

In a couple of places in the code, I need to know if a file
system supports these flags.
I can think of two ways to do this.
#1 - Create a new VFCF_HIDSYS flag that is set via VFS_SET()
       for file systems that support the UF_HIDDEN and UF_SYSTEM
       flags and test for that flag being set.
or
#2 - Write it this way...
      if (strcmp(vp->v_mount->mnt_vfc->vfc_name, "zfs") != 0 ||
          strcmp(vp->v_mount->mnt_vfc->vfc_name, "ufs") != 0 ||
          strcmp(vp->v_mount->mnt_vfc->vfc_name, "msdosfs") != 0 ||
          strcmp(vp->v_mount->mnt_vfc->vfc_name, "tmpfs") != 0)

Which do you think is preferable (or do you have another idea)?

Thanks for any comments, rick