Compatibility with overlayfs

[David Michael]

Hi,

I tried to test EROFS on Linux 5.4 as the root file system and mounted
a writable overlay (with upper layer on tmpfs) over /etc, but I get
ENODATA errors when attempting to modify files.  For example, adding a
user results in "Failed to take /etc/passwd lock: No data available".
Files can be modified after unlinking and restoring them so they're
created on the upper layer.  This is not necessary with other
read-only file systems (at least squashfs or ext4 with the read-only
feature).  I tried while forcing compact and extended inodes.

Is EROFS intended to be usable as a lower layer with overlayfs?

Thanks.

David