From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752037Ab2L0Vs5 (ORCPT ); Thu, 27 Dec 2012 16:48:57 -0500 Received: from mail.parknet.co.jp ([210.171.160.6]:57447 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751492Ab2L0Vsy (ORCPT ); Thu, 27 Dec 2012 16:48:54 -0500 From: OGAWA Hirofumi To: "Darrick J. Wong" Cc: axboe@kernel.dk, lucho@ionkov.net, jack@suse.cz, ericvh@gmail.com, viro@zeniv.linux.org.uk, rminnich@sandia.gov, tytso@mit.edu, martin.petersen@oracle.com, neilb@suse.de, david@fromorbit.com, Zheng Liu , linux-kernel@vger.kernel.org, hch@infradead.org, linux-fsdevel@vger.kernel.org, adilger.kernel@dilger.ca, bharrosh@panasas.com, jlayton@samba.org, v9fs-developer@lists.sourceforge.net, linux-ext4@vger.kernel.org Subject: Re: [PATCH 4/4] block: Optionally snapshot page contents to provide stable pages during write References: <20121213080740.23360.16346.stgit@blackbox.djwong.org> <20121213080811.23360.98131.stgit@blackbox.djwong.org> <877go3z4ra.fsf@devron.myhome.or.jp> <20121227210543.GA20103@blackbox.djwong.org> Date: Fri, 28 Dec 2012 06:48:35 +0900 In-Reply-To: <20121227210543.GA20103@blackbox.djwong.org> (Darrick J. Wong's message of "Thu, 27 Dec 2012 13:40:29 -0800") Message-ID: <87y5gjxj2k.fsf@devron.myhome.or.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org "Darrick J. Wong" writes: >> I think this flag should be separated into "FS provide stable page" and >> "FS needs bounce buffer for stable page". >> >> My fs (I guess btrfs also) provides stable page by better way, and >> doesn't need to wait writeback flags too. What needs is just to avoid >> those stable page stuff. > > How does your fs (are we talking about vfat?) provide stable pages? Basically it copies the data to another page before modifying data only if page has writeback flag. (this is about new fs under development stage.) > btrfs creates its own bdi and doesn't set the "stable pages required" > flag, so it already skips all the stable page stuff. I see. -- OGAWA Hirofumi