From mboxrd@z Thu Jan 1 00:00:00 1970 From: Francis Moreau Subject: Re: PG_updatodate vs BH_updatodate Date: Sun, 23 Nov 2008 21:14:47 +0100 Message-ID: References: <20081123041938.GW3186@webber.adilger.int> <20081123122124.GH5707@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andreas Dilger , linux-fsdevel@vger.kernel.org To: Matthew Wilcox Return-path: Received: from ik-out-1112.google.com ([66.249.90.177]:13697 "EHLO ik-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751811AbYKWUO6 (ORCPT ); Sun, 23 Nov 2008 15:14:58 -0500 Received: by ik-out-1112.google.com with SMTP id c29so1428759ika.5 for ; Sun, 23 Nov 2008 12:14:56 -0800 (PST) In-Reply-To: <20081123122124.GH5707@parisc-linux.org> (Matthew Wilcox's message of "Sun\, 23 Nov 2008 05\:21\:24 -0700") Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Matthew Wilcox writes: > On Sun, Nov 23, 2008 at 01:14:52PM +0100, Francis Moreau wrote: > >> Are there any cases where a page can be partially uptodate ? > > Consider a filesystem with 1k blocks and a system with a page size of 4k. > You have a buffer_head for each of the four blocks that are being kept > in the page, and you want to track their dirty state independently. Sorry but I'm confused since you're taking about the dirty state (tracked by BH_Dirty bit) and I was taking about the uptodate state (tracked by BH_Uptodate bit). > > For file data, no this doesn't happen. But for metadata, it happens >quite easily. Could you give me an example of these metadata ? Thanks Francis