Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750994AbWEQTNX (ORCPT ); Wed, 17 May 2006 15:13:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750995AbWEQTNX (ORCPT ); Wed, 17 May 2006 15:13:23 -0400 Received: from filer.fsl.cs.sunysb.edu ([130.245.126.2]:35051 "EHLO filer.fsl.cs.sunysb.edu") by vger.kernel.org with ESMTP id S1750992AbWEQTNX (ORCPT ); Wed, 17 May 2006 15:13:23 -0400 Date: Wed, 17 May 2006 15:12:12 -0400 From: Josef Sipek To: Hugh Dickins Cc: Arjan van de Ven , linux-kernel@vger.kernel.org Subject: Re: swapper_space export Message-ID: <20060517191212.GA23038@filer.fsl.cs.sunysb.edu> References: <20060516232443.GA10762@filer.fsl.cs.sunysb.edu> <1147864721.3051.17.camel@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2358 Lines: 52 On Wed, May 17, 2006 at 04:52:36PM +0100, Hugh Dickins wrote: > On Wed, 17 May 2006, Arjan van de Ven wrote: > > On Tue, 2006-05-16 at 19:24 -0400, Josef Sipek wrote: > > > I was trying to compile the Unionfs[1] to get it up to sync it up with > > > the kernel developments from the past few months. Anyway, long story > > > short...swapper_space (defined in mm/swap_state.c) is not exported > > > anymore (git commit: 4936967374c1ad0eb3b734f24875e2484c3786cc). This > > > apparently is not an issue for most modules. Troubles arise when the > > > modules include mm.h or any of its relatives. > > > > > > One simply gets a linker error about swapper_space not being defined. > > > The problem is that it is used in mm.h. > > > > don't you think it's really suspect that no other filesystem, in fact no > > other driver in the kernel needs this? Could it just be that unionfs is > > using a wrong API ? Because if that's the case you're patch is just the > > wrong thing. Maybe the unionfs people should try to submit their code > > for review etc...... > > I see no reference to page_mapping() in the unionfs source (and at > present there's no other justifiable modular use of swapper_space); > but my guess would be that Jeff is being more conscientious than is > called for in getting it to sync up with the kernel - That's what happens when one is trying to get ready to send the code to linux-kernel & fs-devel :) > The unionfs source does contain its own inline "sync_page" which > comments that it "is copied verbatim from mm/filemap.c". I'm > guessing Jeff has noticed that it's no longer a verbatim copy, > has made it so, and is thereby involving page_mapping(). Good guess, exactly what happened. > Just use page->mapping as before. Thanks for the advice. > (But I notice that unionfs better not have a tmpfs in its union: > the unionfs use of grab_cache_page is not strictly compatible with > the way tmpfs pages are swapped out under memory pressure.) We have some tmpfs nastiness reported in the bugzilla - I guess this is a good starting point - thanks! Thanks all, Josef "Jeff" Sipek. - 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/