From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org ([205.233.59.134]:37797 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204Ab1ILJ4f convert rfc822-to-8bit (ORCPT ); Mon, 12 Sep 2011 05:56:35 -0400 Subject: Re: [PATCH 03/10] mm: Add support for a filesystem to control swap files From: Peter Zijlstra To: Mel Gorman Cc: Christoph Hellwig , Linux-MM , Linux-Netdev , Linux-NFS , LKML , Andrew Morton , David Miller , Trond Myklebust , Neil Brown Date: Mon, 12 Sep 2011 11:56:09 +0200 In-Reply-To: <20110912093058.GA3207@suse.de> References: <1315566054-17209-1-git-send-email-mgorman@suse.de> <1315566054-17209-4-git-send-email-mgorman@suse.de> <20110909130007.GA11810@infradead.org> <20110909131550.GV14369@suse.de> <20110909133611.GB8155@infradead.org> <1315818285.26517.18.camel@twins> <20110912093058.GA3207@suse.de> Content-Type: text/plain; charset="UTF-8" Message-ID: <1315821369.26517.21.camel@twins> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Mon, 2011-09-12 at 10:34 +0100, Mel Gorman wrote: > On Mon, Sep 12, 2011 at 11:04:45AM +0200, Peter Zijlstra wrote: > > On Fri, 2011-09-09 at 09:36 -0400, Christoph Hellwig wrote: > > > The equivalent of ->direct_IO should be used for both reads and writes. > > > > So the difference between DIO and swapIO is that swapIO needs the block > > map pinned in memory.. So at the very least you'll need those > > swap_{activate,deactivate} aops. The read/write-page thingies could > > indeed be shared with DIO. > > > > I'm travelling at the moment so it'll be later in the week when I investigate > properly but I agree swap_[de|a]ctivate are still necessary. NFS does not > need to pin a block map but it's still necessary for calling xs_set_memalloc. Right.. but I think the hope was that we could replace the current swap bmap hackery with this and simplify the normal swap bits. But yeah, networked filesystems don't really bother with block maps on the client side ;-)