On Thu, Oct 21, 2021 at 12:51 AM Carl Karsten <carl@xxxxxxxxxxxxxxxx> wrote: > > I have 2 overlayfs monts. > > I can nfs export one or the other fine, but not both at the same time, > the client gets the wrong files. Hi Carl, Thanks for the daily overlayfs riddles ;-) This is not an overlayfs issue. It's nfs exports configuration issue. Please read the documentation of fsid export option. Disk filesystems have uuid so they don't need explicit identification. Overlayfs does not have a stable UUID. > > server hosthame negk bullseye ext4 > client twist ubuntu > > juser@negk:~$ cat /etc/exports > # /srv/nfs/rpi/buster/boot/merged *(ro,sync,no_subtree_check,no_root_squash) > /srv/nfs/rpi/buster/root/merged *(ro,sync,no_subtree_check,no_root_squash) In this case, "root" is auto assigned fsid 1 > > juser@negk:~$ ls /srv/nfs/rpi/buster/boot/merged > bcm2708-rpi-b.dtb bcm2710-rpi-3-b-plus.dtb fixup4cd.dat > kernel7.img start4.elf > (snip) > > juser@negk:~$ ls /srv/nfs/rpi/buster/root/merged > bin boot dev etc home lib lost+found media mnt opt proc > root run sbin srv sys tmp usr var > > carl@twist:~/mnt$ sudo mount -t nfs negk:/srv/nfs/rpi/buster/root/merged nfs > carl@twist:~/mnt$ ls nfs > bin boot dev etc home lib lost+found media mnt opt proc > root run sbin srv sys tmp usr var > carl@twist:~/mnt$ sudo umount nfs > > # enable root in negk exports... I think you meant enable "boot" and is that case "boot" gets assigned fsid 1 and "root" gets reassigned fsid 2 > > carl@twist:~/mnt$ sudo mount -t nfs negk:/srv/nfs/rpi/buster/root/merged nfs > carl@twist:~/mnt$ ls nfs > bcm2708-rpi-b.dtb bcm2710-rpi-3-b-plus.dtb fixup4cd.dat > kernel7.img start4.elf > (snip) > It is a bit surprising to me that you get the wrong export after a clean mount, but it doesn't change the core configuration issue. Perhaps nfs client has some fsid cache or you have a deferred umount in the system of negk:/srv/nfs/rpi/buster/root/merged (e.g. due to spawned mount ns or something) and then the "new" nfs mount uses the old resolved fsid 1. In any case, when exporting more than one non-disk filesystem, you should use explicit fsid. Thanks, Amir.
