On Mon, 5 Sept 2022 at 13:09, Miquel Noè <mnoe@xxxxxxxxx> wrote: > > Dear Mr Szeredi, > > My name is Miquel Noè, and I work in a small electronic engineering company although we also develop software for embedded computers using Debian. > > Actually in a Debian 9 we have a fstab file that creates an aufs to set /var folder as read-only and all changes goes to tmpfs that are discharted at reboot/shutdown: > > tmpfs /var.tmp tmpfs defaults,noatime,nosuid,nodev,exec,mode=1777,size=256M 0 0 > none /var aufs br:/var.tmp=rw:/var.ro=ro 0 0 > > Now I need to update to Debian 11 and aufs has been replaced by overlayfs wich I don't know how to configure to have the same behaviour. > > If I add to the new fstab next lines, the result (error reported) is that subfolders /var.tmp/upp and /var.tmp/wrk need to be in the same filesystem: > > tmpfs /var.tmp/upp tmpfs defaults,noatime,nosuid,nodev,exec,mode=1777,size=256M 0 0 > tmpfs /var.tmp/wrk tmpfs defaults,noatime,nosuid,nodev,exec,mode=1777,size=256M 0 0 > overlay /var overlay x-systemd.automount,lowerdir=/var.ro,upperdir=/var.tmp/upp,workdir=/var.tmp/wrk 0 0 > > If I add to the new fstab next lines, the result is that subfolders /var.tmp/upp and /var.tmp/wrk don't exist: > > tmpfs /var.tmp tmpfs defaults,noatime,nosuid,nodev,exec,mode=1777,size=256M 0 0 > overlay /var overlay x-systemd.automount,x-systemd.requires=/var.tmp,lowerdir=/var.ro,upperdir=/var.tmp/upp,workdir=/var.tmp/wrk 0 0 > > Probably the best soution should be that overlay line in fstab forces to create both subfolders, but I don't know how to do that. Can you tell me how should I create or configure upperdir and workdir in fstab? One I can think of is creating a /sbin/mount.overlay script that creates the upper and work directories before proceeding with the actual mount. Thanks, Miklos
