OpenZFS port updated

[Ryan Moeller]

FreeBSD support has been merged into the master branch of the openzfs/zfs repository, and the FreeBSD ports have been switched to this branch.

OpenZFS brings many exciting features to FreeBSD, including:
 * native encryption
 * improved TRIM implementation
 * most recently, persistent L2ARC

Of course, avoid upgrading your pools if you want to keep the option to go back to the base ZFS.

OpenZFS can be installed alongside the base ZFS. Change your loader.conf entry to openzfs_load=“YES” to load the OpenZFS module at boot, and set PATH to find the tools in /usr/local/sbin before /sbin. The base zfs tools are still basically functional with the OpenZFS module, so changing PATH in rc is not strictly necessary.

The FreeBSD loader can boot from pools with the encryption feature enabled, but the root/bootenv datasets must not be encrypted themselves.

The FreeBSD platform support in OpenZFS does not yet include all features present in FreeBSD’s ZFS. Some notable changes/missing features include:
 * many sysctl names have changed (legacy compat sysctls should be added at some point) 
 * zfs send progress reporting in process title via setproctitle
 * extended 'zfs holds -r' (https://svnweb.freebsd.org/base?view=revision&revision=290015)
 * vdev ashift optimizations (https://svnweb.freebsd.org/base?view=revision&revision=254591)
 * pre-mountroot zpool.cache loading (for automatic pool imports)

To the last point, this mainly effects the case where / is on ZFS and /boot is not or is on a different pool. OpenZFS cannot handle this case yet, but work is in progress to cover that use case. Booting directly from ZFS does work.

If there are pools that need to be imported at boot other than the boot pool, OpenZFS does not automatically import yet, and it uses /etc/zfs/zpool.cache rather than /boot/zfs/zpool.cache to keep track of imported pools.  To ensure all pool imports occur automatically, a simple edit to /etc/rc.d/zfs will suffice:

diff --git a/libexec/rc/rc.d/zfs b/libexec/rc/rc.d/zfs
index 2d35f9b5464..8e4aef0b1b3 100755
--- a/libexec/rc/rc.d/zfs
+++ b/libexec/rc/rc.d/zfs
@@ -25,6 +25,13 @@ zfs_start_jail()
 
 zfs_start_main()
 {
+	local cachefile
+
+	for cachefile in /boot/zfs/zpool.cache /etc/zfs/zpool.cache; do
+		if [ -f $cachefile ]; then
+			zpool import -c $cachefile -a
+		fi
+	done
 	zfs mount -va
 	zfs share -a
 	if [ ! -r /etc/zfs/exports ]; then

This will probably not be needed long-term. It is not necessary if the boot pool is the only pool.

Happy testing :)

- Ryan