On Thu, Feb 22, 2024 at 07:19:00AM +0100, Rafał Miłecki wrote: > Hi, > > I'm trying to use overlay to create temporary virtual root filesystem. > I need a copy of / with custom files on top of it. > > To achieve that I used a simple mount like this: > mount -t overlay overlay -o lowerdir=/,upperdir=/tmp/ov/upper,workdir=/tmp/ov/work /tmp/ov/virtual > > In /tmp/ov/virtual/ I can see my main filesystem and I can make temporary > changes to it. Almost perfect! > > The problem are mounts. I have some standard ones: > proc on /proc type proc (rw,nosuid,nodev,noexec,noatime) > sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime) > tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime) > > They are not visible in my virtual root: > # ls -l /tmp/ov/proc/ > # ls -l /tmp/ov/sys/ > # ls -l /tmp/ov/tmp/ > (all empty) > > Would that be possible to make overlayfs follow such mounts in lowerdir? No, this doesn't work: * overlayfs does clone mounts recursively * procfs can't be used as a lower layer So they would need to be bind-mounted on top of these locations.
