From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:60362 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758899Ab1IINP4 (ORCPT ); Fri, 9 Sep 2011 09:15:56 -0400 Date: Fri, 9 Sep 2011 14:15:50 +0100 From: Mel Gorman To: Christoph Hellwig Cc: Linux-MM , Linux-Netdev , Linux-NFS , LKML , Andrew Morton , David Miller , Trond Myklebust , Neil Brown , Peter Zijlstra Subject: Re: [PATCH 03/10] mm: Add support for a filesystem to control swap files Message-ID: <20110909131550.GV14369@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> Content-Type: text/plain; charset=iso-8859-15 In-Reply-To: <20110909130007.GA11810@infradead.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Fri, Sep 09, 2011 at 09:00:08AM -0400, Christoph Hellwig wrote: > On Fri, Sep 09, 2011 at 12:00:47PM +0100, Mel Gorman wrote: > > Currently swapfiles are managed entirely by the core VM by using > > ->bmap to allocate space and write to the blocks directly. This > > patch adds address_space_operations methods that allow a filesystem > > to optionally control the swapfile. > > > > int swap_activate(struct file *); > > int swap_deactivate(struct file *); > > int swap_writepage(struct file *, struct page *, struct writeback_control *); > > int swap_readpage(struct file *, struct page *); > > Just as the last two dozen times this came up: > > NAK > > The right fix is to add a filesystem method to support direct-I/O on > arbitrary kernel pages, instead of letting the wap abstraction leak into > the filesystem. Ok. I confess I haven't investigated this direction at all yet. Is it correct that your previous objection was http://linux.derkeiler.com/Mailing-Lists/Kernel/2009-10/msg00455.html and the direct-IO patchset you were thinking of was http://copilotco.com/mail-archives/linux-kernel.2009/msg87176.html ? If so, are you suggesting that instead of swap_readpage and swap_writepage I look into what is required for swap to use ->readpage method and ->direct_IO aops? -- Mel Gorman SUSE Labs