From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 8 Sep 2001 20:59:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 8 Sep 2001 20:59:08 -0400 Received: from penguin.e-mind.com ([195.223.140.120]:24688 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Sat, 8 Sep 2001 20:58:53 -0400 Date: Sun, 9 Sep 2001 02:59:43 +0200 From: Andrea Arcangeli To: Linus Torvalds , Kernel Mailing List , Alexander Viro Subject: Re: linux-2.4.10-pre5 Message-ID: <20010909025943.F11329@athlon.random> In-Reply-To: <20010908191954.C11329@athlon.random> <20010908151539.F32553@turbolinux.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010908151539.F32553@turbolinux.com>; from adilger@turbolabs.com on Sat, Sep 08, 2001 at 03:15:39PM -0600 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 08, 2001 at 03:15:39PM -0600, Andreas Dilger wrote: > On Sep 08, 2001 10:30 -0700, Linus Torvalds wrote: > > I'll merge the blkdev in pagecache very early in 2.5.x, but I'm a bit > > nervous about merging it in 2.4.x. > > > > That said, if you'll give a description of how you fixed the aliasing > > issues etc, maybe I'd be less nervous. Putting it in the page cache is > > 100% the right thing to do, so in theory I'd really like to merge it > > earlier rather than later, but... > > I think this may have bad interactions with the filesystems, which still > use buffer cache for metadata. If the block devices move to page cache, > so should the filesystems. > > For example, the "tune2fs" program will modify parts of the superblock > from user space (fields that are read-only from the kernel, e.g. label, > reserved blocks count, etc), because it knows that the data read/written > on /dev/hda1 is coherent with that in the kernel for the filesystem > on /dev/hda1. The same is true with e2fsck - the metadata should be > kept coherent from user-space and kernel-space or bad things happen. the patch takes care of that transparently of course, if it didn't you would keep doing long fsck of the root filesystem forever. Andrea