From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: PG_updatodate vs BH_updatodate Date: Sat, 22 Nov 2008 22:19:38 -0600 Message-ID: <20081123041938.GW3186@webber.adilger.int> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7BIT Cc: linux-fsdevel@vger.kernel.org To: Francis Moreau Return-path: Received: from sca-es-mail-1.Sun.COM ([192.18.43.132]:63973 "EHLO sca-es-mail-1.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753536AbYKWETm (ORCPT ); Sat, 22 Nov 2008 23:19:42 -0500 Received: from fe-sfbay-10.sun.com ([192.18.43.129]) by sca-es-mail-1.sun.com (8.13.7+Sun/8.12.9) with ESMTP id mAN4Jfwf024113 for ; Sat, 22 Nov 2008 20:19:41 -0800 (PST) Received: from conversion-daemon.fe-sfbay-10.sun.com by fe-sfbay-10.sun.com (Sun Java System Messaging Server 6.2-8.04 (built Feb 28 2007)) id <0KAR00D01QKG5100@fe-sfbay-10.sun.com> (original mail from adilger@sun.com) for linux-fsdevel@vger.kernel.org; Sat, 22 Nov 2008 20:19:41 -0800 (PST) In-reply-to: Content-disposition: inline Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Nov 21, 2008 23:03 +0100, Francis Moreau wrote: > I'm wondering if there's any difference between these 2 flags except > that one is a page flag and the other one is a buffer head flag. > > But in my understanding these 2 flags means that the page contains > uptodate data. So the buffer head flag seems useless since it could be > calculated from bh->b_page->flags. There may be multiple buffers on a single page, and in some cases one buffer on a page can be uptodate while another buffer on the same page is not. This can be confusing at times, but I don't know if there is any easy way to avoid it. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.