If we have a mount point at /mnt
and a syncpoint at /mnt/sync
umount /mnt fails to remove the syncmount /mnt/sync
why does the unmount fail to remove the sync point, and why does switching the order fix it?
Because the removing of syncpoint logic needs to look up the mount point, to resolve the path, if the mount point is already removed, the resolution will come back empty.
Hence we need to switch the order.