Please backport to the following patch which was merged upstream.

It should apply to linux-5.4.y and later.

commit 29be9100aca2915fab54b5693309bc42956542e5 Author: Marc Dionne marc.dionne@auristor.com1 Date:   Fri May 24 17:17:55 2024 +0100

afs: Don't cross .backup mountpoint from backup volume

Don't cross a mountpoint that explicitly specifies a backup volume     (target is <vol>.backup) when starting from a backup volume.

It it not uncommon to mount a volume's backup directly in the volume     itself.  This can cause tools that are not paying attention to get     into a loop mounting the volume onto itself as they attempt to     traverse the tree, leading to a variety of problems.

This doesn't prevent the general case of loops in a sequence of     mountpoints, but addresses a common special case in the same way     as other afs clients.

Reported-by: Jan Henrik Sylvester jan.henrik.sylvester@uni-hamburg.de     Link: http://lists.infradead.org/pipermail/linux-afs/2024-May/008454.html     Reported-by: Markus Suvanto markus.suvanto@gmail.com     Link: http://lists.infradead.org/pipermail/linux-afs/2024-February/008074.html     Signed-off-by: Marc Dionne marc.dionne@auristor.com     Signed-off-by: David Howells dhowells@redhat.com     Link: https://lore.kernel.org/r/768760.1716567475@warthog.procyon.org.uk     Reviewed-by: Jeffrey Altman jaltman@auristor.com     cc: linux-afs@lists.infradead.org     Signed-off-by: Christian Brauner brauner@kernel.org

Thank you.

Jeffrey Altman