From owner-freebsd-fs@FreeBSD.ORG  Thu Jul 21 19:10:37 2005
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
X-Original-To: fs@freebsd.org
Delivered-To: freebsd-fs@FreeBSD.ORG
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 2C4CE16A421
	for <fs@freebsd.org>; Thu, 21 Jul 2005 19:10:37 +0000 (GMT)
	(envelope-from igor.shmukler@gmail.com)
Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.199])
	by mx1.FreeBSD.org (Postfix) with ESMTP id B73B343D6D
	for <fs@freebsd.org>; Thu, 21 Jul 2005 19:10:31 +0000 (GMT)
	(envelope-from igor.shmukler@gmail.com)
Received: by zproxy.gmail.com with SMTP id c3so40016nze
	for <fs@freebsd.org>; Thu, 21 Jul 2005 12:10:31 -0700 (PDT)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com;
	h=received:message-id:date:from:reply-to:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition;
	b=q10kAIOoB6TwJY4GAkJr8JZoP+J3yc3jJhvVzLMocW4Iv53buKmTDRFgU011N9HrKmyjMS/auwTz5bVomvAAphHCpFT+VnJM/ZEqkUdZzKYOnfv/+EBetyRiYeJfr1Qs8cj6A6EVudB4/AeV1SUXjn5CUnSh7TIfPQahtfId5Yo=
Received: by 10.36.129.16 with SMTP id b16mr1235566nzd;
	Thu, 21 Jul 2005 12:10:30 -0700 (PDT)
Received: by 10.36.119.12 with HTTP; Thu, 21 Jul 2005 12:10:30 -0700 (PDT)
Message-ID: <6533c1c9050721121030016b7d@mail.gmail.com>
Date: Thu, 21 Jul 2005 15:10:30 -0400
From: Igor Shmukler <igor.shmukler@gmail.com>
To: fs@freebsd.org, hackers@freebsd.org, dillon@apollo.backplane.com
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Cc: 
Subject: per file lock list
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Igor Shmukler <igor.shmukler@gmail.com>
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: Thu, 21 Jul 2005 19:10:37 -0000

Hi,

We have a question: how to get all POSIX locks for a given file?

As far as I know, existing API does not allow to retrieve all file
locks. Therefore, we need to use kernel internal structures to get all
applied locks. Unfortunately, a head of list with file locks is
attached to inode rather then vnode. As result, it is much harder to
get the lock list head due to the need to know exact inode type that
is hidden behind the vnode.

Of course, the problem could be resolved in a hackish way: we may get
the address of VOP_ADVLOCK() method and compare it with all known FS
methods, that handles this VOP operation: (ufs_advlock, etc.) and
therefore apply a proper type cast to vnode->v_data to get valid
inode. However, this would be a last resort.

So the question: is there an elegant way to get the lock list for a given f=
ile?

Thank you in advance.