Comment 14 for bug 1905623

I just read about the correct way to report a bug or fix to the gnulib developers. I have emailed them as below:
Date: Sat, 13 Feb 2021 at 12:40
Subject: Suggested fix to mountlist.c: Define fuse.portal, devtmpfs and squashfs mounts as dummy
To: <email address hidden>
Cc: <email address hidden>
Hi gnulib developers,
At present many gnulib users encounter this error:
Running 'df' as user (not root) causes results in output that includes
this error message:
"df: /run/user/1000/doc: Operation not permitted"
I would like to pass on to you a suggested fix:

@@ -164,7 +164,10 @@
 #define ME_DUMMY_0(Fs_name, Fs_type) \
   (strcmp (Fs_type, "autofs") == 0 \
+ || strcmp (Fs_type, "devtmpfs") == 0 \
+ || strcmp (Fs_type, "fuse.portal") == 0 \
    || strcmp (Fs_type, "proc") == 0 \
+ || strcmp (Fs_type, "squashfs") == 0 \
    || strcmp (Fs_type, "subfs") == 0 \
    /* for Linux 2.6/3.x */ \
    || strcmp (Fs_type, "debugfs") == 0 \

Julian Klode, from Ubuntu, deserves credit for this suggested fix. He
published a patch that has been included in the Ubuntu Hirsute 21.04
package: coreutils 8.32-4ubuntu2. See

    https://bugs.launchpad.net/ubuntu/+source/xdg-desktop-portal/+bug/19056232.
    https://launchpadlibrarian.net/510003931/coreutils_8.32-4ubuntu1_8.32-4ubuntu2.diff.gz
    I have cc'ed Julian in this email.
    The patch addresses a problem that particularly affects gnulib users
    with fuse.portal mounts, such as users who have installed Flatpak.
    This is a significant problem for users who depend on df not returning
    an error exit code in their scripts. Julian's bug report said:
    "/run/user/1000/doc is a fuse.portal mount point, but statfs() return
    EPERM, hence df produces an error message. Maybe statfs() is not
    implemented, but it would be good to quieten this down (df even does
    not allow me to ignore it, probably because it looks at statfs to find
    out fs type, so my fs type ignoring doesn't work)."
    This problem has also been reported on Fedora 32 here:
    flatpak/xdg-desktop-portal#512
    Kind regards,
    Daniel