bug#66441: df: duplicated NFS4 bind mounts with the same device

Hey Lukáš,

You wrote:

> I get duplicates on this reproducer with plain df, i.e. without -a.
> Originally, the issue was reported for RHEL 8 [1] but I can reproduce
> it even on the latest stable release of coreutils shipped with Fedora
> Rawhide.
> 
> $ mkdir -p /original /bind1 /bind2
> $ mount.nfs server:/nfs /original -v 
> mount.nfs: timeout set for Fri Mar 10 10:50:59 2023
> mount.nfs: trying text-based options 'vers=4.2,addr=192.168.122.40,clientaddr=192.168.122.121'
> $ mount --bind /original/testd1 /bind1 -v
> mount: /original/testd1 bound on /bind1.
> $ mount --bind /original/testd2 /bind2 -v
> mount: /original/testd2 bound on /bind2.
> $ df -ht nfs4 
> Filesystem Size Used Avail Use% Mounted on
> server:/nfs 97M 5.4M 92M 6% /original
> server:/nfs/testd1 97M 5.4M 92M 6% /bind1 
> server:/nfs/testd2 97M 5.4M 92M 6% /bind2
> $ mount --bind /original/testd1 /bind1 -v
> mount: /original/testd1 bound on /bind1.
> $ mount --bind /original/testd2 /bind2 -v
> mount: /original/testd2 bound on /bind2.
> $ df -ht nfs4
> Filesystem Size Used Avail Use% Mounted on
> server:/nfs 97M 5.4M 92M 6% /original
> server:/nfs/testd1 97M 5.4M 92M 6% /bind1 
> server:/nfs/testd2 97M 5.4M 92M 6% /bind2 
> server:/nfs/testd1 97M 5.4M 92M 6% /bind1 <- dup
> server:/nfs/testd2 97M 5.4M 92M 6% /bind2 <— dup
> 
> [1] https://issues.redhat.com/browse/RHEL-5649

I see that the linked Red Hat Jira for this issue mentions it was fixed
by your patch [1], which was a part of coreutils-9.11. I'll go ahead and
close this now, but feel to re-open it if I misread that.

Collin

[1] https://lists.gnu.org/archive/html/coreutils/2026-04/msg00069.html