ath79-NAND: overlayfs doesn't support directory move => I/O error

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Hi,

I'm wondering if this is bug or a known fact on NAND. I build a NAND image from snapshot with the imagebuilder:

openwrt-ath79-nand-glinet_gl-ar750s-nor-nand-squashfs-sysupgrade.bin

and installed it on an GL.inet AR750s. The system boots and is ready. I have a setup where I move /etc/config and symlink it for atomic config updates. But the jobs that actually moves /etc/config gets:

root@NW-C1000M:~# mv /etc/config/ /etc/config-orig
mv: can't remove '/etc/config/': I/O error

If I do the exact same mv on NOR image

root@NW-C1000M:~# mv /etc/config/ /etc/config-orig
root@NW-C1000M:~# mv /etc/config-orig/ /etc/config

i found the following message in the boot log. Not sure if it is at all related but it doesn't appear on NOR image:

[   19.819306] overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.

any hints very much appreciated.
1000x