linux-formula/linux/files/setup-loopback-device.systemd

[Unit]
Description=Setup {{ device_name }} device
DefaultDependencies=no
After=systemd-udev-settle.service
Before=lvm2-activation-early.service
Wants=systemd-udev-settle.service

[Service]
{# The command is prefixed with '-' to consider it a success if the loopback device is already setup #}
ExecStart=-/sbin/losetup {{ device_name }} {{ file }}
Type=oneshot

[Install]
WantedBy=local-fs.target