The lab adds two spare disks, each with an ext4 filesystem that isn't mounted: /dev/loop40p1 (1 GiB, standing in for the one from 104.1) and /dev/loop41 (256 MiB, labeled stick, standing in for a USB stick). They come back at every boot, before filesystems are mounted. It also creates user uma (password Lab-Pass-1). Write answers to the files in /root/lab-answers/.

Tasks

Mount /dev/loop40p1 by hand on /mnt/data, create a file in it, cd into it in another terminal, and try to unmount. Find the blocker with fuser -vm.
Add it to /etc/fstab by UUID, still at /mnt/data, check with findmnt --verify and mount -a, and reboot to prove it comes back.
Find the mount unit systemd made for it, and read it with systemctl cat. Write the unit's name to /root/lab-answers/3.
Add a noauto,users line for /dev/loop41 at /mnt/stick, and mount and unmount it as uma.
Remount /mnt/data read-only with mount -o remount,ro, try to write to it, and remount it read-write. Check it yourself: the write fails with "Read-only file system" in between.

Hints

mount, umount, fuser -vm /mnt/data; lsof /mnt/data works too.
blkid, UUID=... /mnt/data ext4 defaults 0 2; systemctl daemon-reload after editing fstab.
systemctl list-units --type=mount, systemd-escape -p --suffix=mount /mnt/data.
LABEL=stick /mnt/stick ext4 noauto,users 0 0; then su - uma and mount /mnt/stick.
touch /mnt/data/x while it's read-only.