Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262007AbUDELnV (ORCPT ); Mon, 5 Apr 2004 07:43:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262043AbUDELnU (ORCPT ); Mon, 5 Apr 2004 07:43:20 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:1174 "EHLO atrey.karlin.mff.cuni.cz") by vger.kernel.org with ESMTP id S262007AbUDELnO (ORCPT ); Mon, 5 Apr 2004 07:43:14 -0400 Date: Mon, 5 Apr 2004 13:43:12 +0200 From: Pavel Machek To: "Eric W. Biederman" Cc: =?iso-8859-2?Q?J=F6rn?= Engel , Jamie Lokier , mj@ucw.cz, jack@ucw.cz, "Patrick J. LoPresti" , linux-kernel@vger.kernel.org Subject: Re: [PATCH] cowlinks v2 Message-ID: <20040405114312.GA31036@atrey.karlin.mff.cuni.cz> References: <20040402180128.GA363@elf.ucw.cz> <20040402181707.GA28112@wohnheim.fh-wedel.de> <20040402182357.GB410@elf.ucw.cz> <20040402200921.GC653@mail.shareable.org> <20040402213933.GB246@elf.ucw.cz> <20040403010425.GJ653@mail.shareable.org> <20040403194344.GA5477@mail.shareable.org> <20040405083549.GD28924@wohnheim.fh-wedel.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1052 Lines: 31 Hi! > > And it looks like Pavel already found the solution. Whenever doing > > something fishy that would confuse the page cache, we > > 1. lock > > 2. invalidate page cache for all files belonging to that cow entity > > 3. copyfile(), write(), or whatever > > 4. unlock > > > > This is always possibly, because page cache for cow-files is never > > read-write. If it was, we would have done 1-4 before and now have a > > regular (non-cow) file. > > > > Did I miss something? > > I know a writable mmap needs to trigger a copy in that case. > And then are fun cases with MAP_FIXED which may mean invalidation > is not allowed. How is "invalidation not allowed" for MAP_FIXED? Application will never see the fault... Pavel -- Horseback riding is like software... ...vgf orggre jura vgf serr. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/