Regression with ZFS on recent current

Hi!

While testing portshaker I found a regression in latest current.

portshaker depends on ZFS(when enabling ZFS support) remounting
filesystems on the fly when changing the mountpoint property. This is
working as expected on 9.x while on 10-current is not working. Problem
has appeared sometime before October 3rd.

Here is some sample output from a9.x machine and a 10-current one:

root_at_micro:~ [0]# uname -a
FreeBSD micro.madpilot.net 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #0
r239180: Sat Aug 11 00:14:47 CEST 2012
root_at_micro.madpilot.net:/usr/obj/usr/src/sys/MICRO  amd64
root_at_micro:~ [0]# zfs create tank/test
root_at_micro:~ [0]# touch /test/baz
root_at_micro:~ [0]# zfs set mountpoint=/foo tank/test
root_at_micro:~ [0]# ls -ld /foo
drwxr-xr-x  2 root  wheel  3 Oct 17 19:18 /foo
root_at_micro:~ [0]# ls -l /foo/
total 1
-rw-r--r--  1 root  wheel  0 Oct 17 19:18 baz
root_at_micro:~ [0]# zfs list tank/test
NAME        USED  AVAIL  REFER  MOUNTPOINT
tank/test   144K   826G   144K  /foo


root_at_marvin:~ [0]# uname -a
FreeBSD marvin.madpilot.net 10.0-CURRENT FreeBSD 10.0-CURRENT #7
r241638: Wed Oct 17 14:33:18 CEST 2012
root_at_marvin.madpilot.net:/usr/obj/usr/src/sys/MARVIN  amd64
root_at_marvin:~ [0]# zfs create tank/test
root_at_marvin:~ [0]# touch /test/baz
root_at_marvin:~ [0]# zfs set mountpoint=/foo tank/test
root_at_marvin:~ [0]# ls -ld /foo
ls: /foo: No such file or directory
root_at_marvin:~ [1]# ls -l /foo/
ls: /foo/: No such file or directory
root_at_marvin:~ [1]# ls -ld /test
drwxr-xr-x  2 root  wheel  3 Oct 17 19:19 /test
root_at_marvin:~ [0]# zfs list tank/test
NAME        USED  AVAIL  REFER  MOUNTPOINT
tank/test    31K   240G    31K  /foo


Is this known? is the new behavior expected?

Am I doing something stupid?

Thanks in advance

-- 
Guido Falsi <mad_at_madpilot.net>