From owner-freebsd-fs@FreeBSD.ORG  Mon Jun 28 11:38:42 2010
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C44AF106566B
	for <freebsd-fs@freebsd.org>; Mon, 28 Jun 2010 11:38:42 +0000 (UTC)
	(envelope-from bsd@nezmer.info)
Received: from mail.nezmer.info (nezmer.info [97.107.142.36])
	by mx1.freebsd.org (Postfix) with ESMTP id A6BAC8FC1B
	for <freebsd-fs@freebsd.org>; Mon, 28 Jun 2010 11:38:42 +0000 (UTC)
Date: Mon, 28 Jun 2010 14:38:37 +0300
From: Nezmer <bsd@nezmer.info>
To: freebsd-fs@freebsd.org
Message-ID: <20100628113837.GA98334@mail>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.5.20 (2009-06-14)
Subject: nullmounting zfs fs with children
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 28 Jun 2010 11:38:42 -0000

Hi, 

Is this normal behaviour?

# zfs create -p -o mountpoint=/zfstest/subdir0/subdir1/subdir2 POOL/zfstest/subdir0/subdir1/subdir2
# echo 2 > /zfstest/subdir0/subdir1/subdir2/file2
# echo 1 > /zfstest/subdir0/subdir1/file1

# find /zfstest
/zfstest
/zfstest/subdir0
/zfstest/subdir0/subdir1
/zfstest/subdir0/subdir1/file1
/zfstest/subdir0/subdir1/subdir2
/zfstest/subdir0/subdir1/subdir2/file2

# mkdir /nulltest
# mount_nullfs /zfstest /nulltest

# find /nulltest
/nulltest
/nulltest/subdir0
/nulltest/subdir0/subdir1
/nulltest/subdir0/subdir1/file1
/nulltest/subdir0/subdir1/subdir2

# echo 0 > /zfstest/subdir0/file0

# find /zfstest
/zfstest
/zfstest/subdir0
/zfstest/subdir0/subdir1
/zfstest/subdir0/subdir1/file1
/zfstest/subdir0/subdir1/subdir2
/zfstest/subdir0/subdir1/subdir2/file2
/zfstest/subdir0/file0

# find /nulltest
/nulltest
/nulltest/subdir0
/nulltest/subdir0/subdir1
/nulltest/subdir0/subdir1/file1
/nulltest/subdir0/subdir1/subdir2
/nulltest/subdir0/file0

# umount /nulltest
# zfs destroy -r POOL/zfstest

# find /zfstest
/zfstest
/zfstest/subdir0
/zfstest/subdir0/subdir1
/zfstest/subdir0/subdir1/file1
/zfstest/subdir0/subdir1/subdir2
/zfstest/subdir0/file0

# find /nulltest
/nulltest
/nulltest/subdir0
/nulltest/subdir0/subdir1
/nulltest/subdir0/subdir1/file1
/nulltest/subdir0/subdir1/subdir2
/nulltest/subdir0/file0

I noticed this behaviour when I wanted to nullmount my "/usr/home" inside a chroot:

# mount|grep /usr/home
POOL/usr/home on /usr/home (zfs, local, noatime)
POOL/usr/home/nezmer on /usr/home/nezmer (zfs, local, noatime)
POOL/usr/home/nezmer/Mail on /usr/home/nezmer/Mail (zfs, local, noatime)
POOL/usr/home/nezmer/pkgs on /usr/home/nezmer/pkgs (zfs, local, noatime)
POOL/usr/home/nezmer/srcs on /usr/home/nezmer/srcs (zfs, local, noatime)
/usr/home on /chroot/usr/home (nullfs, local)

# find /usr/home -maxdepth 4|wc
    7267    7289  390127

# find /chroot/usr/home
/chroot/usr/home
/chroot/usr/home/nezmer