From owner-svn-src-all@FreeBSD.ORG Mon May 17 16:28:11 2010 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 55FFF106564A; Mon, 17 May 2010 16:28:11 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mail.zoral.com.ua (mx0.zoral.com.ua [91.193.166.200]) by mx1.freebsd.org (Postfix) with ESMTP id DF2808FC15; Mon, 17 May 2010 16:28:10 +0000 (UTC) Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by mail.zoral.com.ua (8.14.2/8.14.2) with ESMTP id o4HGSJKh019060 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 17 May 2010 19:28:19 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4) with ESMTP id o4HGS6SI046648; Mon, 17 May 2010 19:28:06 +0300 (EEST) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.4/8.14.4/Submit) id o4HGS628046639; Mon, 17 May 2010 19:28:06 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 17 May 2010 19:28:06 +0300 From: Kostik Belousov To: Matthew Fleming Message-ID: <20100517162806.GM83316@deviant.kiev.zoral.com.ua> References: <201005122124.o4CLOk3b027904@svn.freebsd.org> <20100516050651.GZ83316@deviant.kiev.zoral.com.ua> <06D5F9F6F655AD4C92E28B662F7F853E021D4D66@seaxch09.desktop.isilon.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="n8d7KAgWmJ23Ts4y" Content-Disposition: inline In-Reply-To: <06D5F9F6F655AD4C92E28B662F7F853E021D4D66@seaxch09.desktop.isilon.com> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: clamav-milter 0.95.2 at skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-2.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_50, DNS_FROM_OPENWHOIS autolearn=no version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on skuns.kiev.zoral.com.ua Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, Zachary Loafman , src-committers@freebsd.org Subject: Re: svn commit: r208003 - in head/sys: kern sys X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 May 2010 16:28:11 -0000 --n8d7KAgWmJ23Ts4y Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, May 17, 2010 at 08:33:52AM -0700, Matthew Fleming wrote: > > From: Kostik Belousov [mailto:kostikbel@gmail.com] > > On Wed, May 12, 2010 at 09:24:46PM +0000, Zachary Loafman wrote: > > > Author: zml > > > Date: Wed May 12 21:24:46 2010 > > > New Revision: 208003 > > > URL: http://svn.freebsd.org/changeset/base/208003 > > >=20 > > > Log: > > > Add VOP_ADVLOCKPURGE so that the file system is called when purging > > > locks (in the case where the VFS impl isn't using lf_*) > > > =20 > > > Submitted by: Matthew Fleming > > > Reviewed by: zml, dfr > >=20 > > After looking at what happen to nullfs, see r208003, I wonder why > > the vop is needed. It is called after VOP_RECLAIM is called by vgonel(), > > after fs-specific data are destroyed. So, on the one hand, vop can only > > operate on struct vnode proper, on the other hand, the actions performed > > by vop_advlockpurge implementation can be done by vop_reclaim as well. > >=20 > > Could you, please, give some details on the supposed use of the vop ? >=20 > >From a design perspective, it makes little sense to allow overriding > the advlock operation, but not the purge. A specific example is if an > implementation does not use struct lockf to implement advlock, then > the hack you mention of purging in VOP_RECLAIM is needed. > > After looking over the history of the changes, I believe it would be > sufficient to have the lock purge done before the reclaim. The vnode > is locked exclusively for both operations, so I don't believe there > will be any timing windows. But I am still not 100% sure when the file > lock is used versus the interlock for serializing access to various > fields. > > The advlock VOPs are analogous to the regular VOP_LOCK in that we > expect an implementation may override the VOP and also the data > structures used, e.g. to not use the vnode's v_lock field for the > VOP_LOCK. Thus any code which refers to v_lockf should be wrapped in a > VOP to allow correct overriding. Essentially, my argument is that whatever you do in VOP_ADVLOCKPURGE, can be and should be done in VOP_RECLAIM. This would also cover the v_data issue. --n8d7KAgWmJ23Ts4y Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAkvxbpUACgkQC3+MBN1Mb4jcwQCeItE83uff8FnY+WbI7H0xwDC+ QQAAoMFTDaTO9L/6gYGutbLyqpOoIJZd =PJi1 -----END PGP SIGNATURE----- --n8d7KAgWmJ23Ts4y--