overlayfs-etc on top of dm-verity?

[Michael Opdenacker <michael.opdenacker@rootcommit.com>]

Hi Slava and community,

Do you know if overlayfs and in particular our overlayfs-etc class works 
when /etc is on a dm-verity root filesystem?

Without dm-verity (regular ext4 or erofs root filesystem), everything 
looks all right:
# mount | grep overlay
/data/overlay-etc/upper on /etc type overlay 
(rw,relatime,lowerdir=/etc,upperdir=/data/overlay-etc/upper,workdir=/data/overlay-etc/work,uuid=on)

When /etc is on /dev/mapper/rootfs (dm-verity), everything seems messed up:
# mount | grep overlay
overlay on /var/cache type overlay 
(rw,relatime,lowerdir=/var/cache,upperdir=/var/volatile/cache,workdir=/var/volatile/.cache-work,uuid=on)
overlay on /var/lib type overlay 
(rw,relatime,lowerdir=/var/lib,upperdir=/var/volatile/lib,workdir=/var/volatile/.lib-work,uuid=on)
overlay on /var/spool type overlay 
(rw,relatime,lowerdir=/var/spool,upperdir=/var/volatile/spool,workdir=/var/volatile/.spool-work,uuid=on)
overlay on /srv type overlay 
(rw,relatime,lowerdir=/srv,upperdir=/var/volatile/srv,workdir=/var/volatile/.srv-work,uuid=on)

Systemd may be messing up, as only in this case, it does:
          Starting Bind mount volatile /var/cache...
          Starting Bind mount volatile /var/lib...
          Starting Bind mount volatile /var/spool...
          Starting Bind mount volatile /srv...

But these bind mounts show up as overlay mounts!

Has anyone already encountered such an issue?
Thanks in advance,
Cheers
Michael.

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