zfs-mount-generator should use WantsMountsFor= instead of RequiresMountsFor=

[mschiff]

System information

Type	Version/Name
Distribution Name	Gentoo
Distribution Version	current
Kernel Version	6.6.13-gentoo-dist
Architecture	x86_64
OpenZFS Version	2.2.2

Describe the problem you're observing

Using systemd ZFS mounts are being unmounted again after being mounted on boot if keyfile was loaded from a automount device. Please see (https://github.com/systemd/systemd/issues/31280):

We added WantsMountsFor= (https://github.com/systemd/systemd/pull/30214) for that use case. zfs-mount-generator needs to be taught to use that instead, which is beyond the scope of systemd's bug tracker.

Describe how to reproduce the problem

• use systemd
• have USB device with keyfile on it
• have dataset with property like keylocation=file:///mnt/stick/zfs.key
• use zfs-mount-generator units to unlock/mount encrypted datasets
• have a /etc/fstab entry like: /dev/disk/by-id/usb-some-id-of-device /mnt/stick ext2 x-systemd.device-timeout=5min,x-systemd.automount,x-systemd.idle-timeout=5s 0 0

Now after loading the key from the usb device all encrypted zfs datasets are being unmounted as soon as /mnt/stick unmount is triggered by systemd

Include any warning/errors/backtraces from the system logs