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

[Jeffrey E Altman]

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@xxxxxxxxxxxx>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@xxxxxxxxxxxxxx>
    Link: 
http://lists.infradead.org/pipermail/linux-afs/2024-May/008454.html
    Reported-by: Markus Suvanto <markus.suvanto@xxxxxxxxx>
    Link: 
http://lists.infradead.org/pipermail/linux-afs/2024-February/008074.html
    Signed-off-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
    Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
    Link: 
https://lore.kernel.org/r/768760.1716567475@xxxxxxxxxxxxxxxxxxxxxx
    Reviewed-by: Jeffrey Altman <jaltman@xxxxxxxxxxxx>
    cc: linux-afs@xxxxxxxxxxxxxxxxxxx
    Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>

Thank you.

Jeffrey Altman

Attachment: smime.p7s
Description: S/MIME Cryptographic Signature