Backport request: commit 29be9100aca2915fab54b5693309bc42956542e5 ("afs: Don't cross .backup mountpoint from backup volume")

[Jeffrey E Altman <jaltman@auristor.com>]

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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.com>1
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




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