From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261186AbULAAfY (ORCPT ); Tue, 30 Nov 2004 19:35:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261206AbULAAec (ORCPT ); Tue, 30 Nov 2004 19:34:32 -0500 Received: from fw.osdl.org ([65.172.181.6]:59627 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261171AbULAAaG (ORCPT ); Tue, 30 Nov 2004 19:30:06 -0500 Date: Tue, 30 Nov 2004 16:33:52 -0800 From: Andrew Morton To: Blaisorblade Cc: linux-kernel@vger.kernel.org, jdike@addtoit.com, bstroesser@fujitsu-siemens.com, user-mode-linux-devel@lists.sourceforge.net, kraxel@bytesex.org Subject: Re: VFS interactions with UML and other big UML changes (was: Re: [patch 1/2] Uml - first part rework of run_helper() and users.) Message-Id: <20041130163352.62840d12.akpm@osdl.org> In-Reply-To: <200412010120.39579.blaisorblade_spam@yahoo.it> References: <20041130200845.2C5058BAFE@zion.localdomain> <20041130152017.129e134c.akpm@osdl.org> <200412010120.39579.blaisorblade_spam@yahoo.it> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i586-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Blaisorblade wrote: > > static struct address_space_operations hostfs_aops = { > .writepage = hostfs_writepage, > .readpage = hostfs_readpage, > /* .set_page_dirty = __set_page_dirty_nobuffers, */ > .prepare_write = hostfs_prepare_write, > .commit_write = hostfs_commit_write > }; > > Actually, hostfs is a nodev filesystem, but I simply don't know if that > implies that it uses no buffers. So, should > > .set_page_dirty = __set_page_dirty_nobuffers > > be uncommented? Or should it be deleted (leaving it there is not a good > option). See the operation of set_page_dirty(). If you have NULL ->set_page_dirty a_op then set_page_dirty() will fall through to __set_page_dirty_buffers(). If your fs never sets PG_private then __set_page_dirty_buffers() will just do what __set_page_dirty_nobuffers() does. Without having looked at it, I'm sure that hostfs does not use buffer_heads. So setting your ->set_page_dirty a_op to point at __set_page_dirty_nobuffers() is a reasonable thing to do - it'll provide a slight speedup.