Proper order of unmount for zfs partition / dmcrypt

[uint]

Hi! I have a setup with two disk partitions encrypted with dmcrypt (LUKS), and over them there's a zfs mirrored pool. I also have OpenRC.

At the system boot, the startup order is correct: first I get prompted for the passphrases of the encrypted partitions, then dmcrypt unlocks them, then zfs imports the pool and mounts the partition to the file system.

However, at shutdown it seems that zfs does not unmount its partition, either in time, or at all. This leads to the shutdown log having dmcrypt complaining that encrypted devices cannot be unmounted (as they are busy). I don't have the log at hand, as this normally happens after the syslog-ng shutdown.

This does not seem to do much harm, but still looks messy, and I'd like to set up the correct shutdown order, where:
- zfs partition is unmounted from the fs
- zfs stops the pool (however it calls this operation)
- dmcrypt stops the underlying encrypted partitions

But I'm not sure how to do that, and specifically what controls the order in which OpenRC stops services.
I tried to set