From owner-freebsd-fs@FreeBSD.ORG  Sun Oct  7 18:43:59 2012
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: fs@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 5A0901065670;
	Sun,  7 Oct 2012 18:43:59 +0000 (UTC)
	(envelope-from gibbs@scsiguy.com)
Received: from aslan.scsiguy.com (ns1.scsiguy.com [70.89.174.89])
	by mx1.freebsd.org (Postfix) with ESMTP id 255A38FC08;
	Sun,  7 Oct 2012 18:43:58 +0000 (UTC)
Received: from macbook.scsiguy.com (macbook.scsiguy.com [192.168.0.99])
	(authenticated bits=0)
	by aslan.scsiguy.com (8.14.5/8.14.5) with ESMTP id q97Ihw7r084465
	(version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO);
	Sun, 7 Oct 2012 12:43:58 -0600 (MDT)
	(envelope-from gibbs@scsiguy.com)
Content-Type: text/plain; charset=iso-8859-1
Mime-Version: 1.0 (Mac OS X Mail 6.2 \(1499\))
From: "Justin T. Gibbs" <gibbs@scsiguy.com>
In-Reply-To: <5071A071.1020800@FreeBSD.org>
Date: Sun, 7 Oct 2012 12:44:02 -0600
Content-Transfer-Encoding: 7bit
Message-Id: <97D56E7F-1284-4FB1-8C83-9EE04FE4F59F@scsiguy.com>
References: <76CBA055-021F-458D-8978-E9A973D9B783@scsiguy.com>
	<506EB43B.8050204@FreeBSD.org> <5071A071.1020800@FreeBSD.org>
To: Andriy Gapon <avg@FreeBSD.org>
X-Mailer: Apple Mail (2.1499)
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7
	(aslan.scsiguy.com [192.168.0.4]);
	Sun, 07 Oct 2012 12:43:58 -0600 (MDT)
Cc: Konstantin Belousov <kib@FreeBSD.org>,
	Pawel Jakub Dawidek <pjd@FreeBSD.org>, fs@FreeBSD.org
Subject: Re: ZFS: Deadlock during vnode recycling
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: Sun, 07 Oct 2012 18:43:59 -0000

On Oct 7, 2012, at 9:32 AM, Andriy Gapon <avg@FreeBSD.org> wrote:

> In fact here is a real patch that I would like to propose:
> http://people.freebsd.org/~avg/zfs-getnewvnode_reserve.diff

OS-X has these same types of problems and I talked with Don Brady
of the OS-X ZFS port about them during ZFS day.  It sounds like he
explicitly pre-allocates vnodes in these code paths instead of
relying on a reserve pool.  I plan to review his work since I expect
he's found and fixed problems we don't even know we have yet.

My only complaint with this patch is that it doesn't include stats
counters for these rare conditions so that I can validate that the
code is exercised during a test suite.  Can you merge in the kstat
portion of the change I proposed?

--
Justin