From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 2/2] ext2: Add blk_issue_flush() to syncing paths Date: Wed, 14 Jan 2009 19:27:06 +0100 Message-ID: <20090114182706.GA24719@elf.ucw.cz> References: <1231945948-23676-1-git-send-email-jack@suse.cz> <1231945948-23676-2-git-send-email-jack@suse.cz> <20090114101834.fbb9ea12.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jan Kara , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Andrew Morton Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:55879 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753156AbZANS1Q (ORCPT ); Wed, 14 Jan 2009 13:27:16 -0500 Content-Disposition: inline In-Reply-To: <20090114101834.fbb9ea12.akpm@linux-foundation.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi! > Also, the changelog needs some work, methinks. > > /** > * blkdev_issue_flush - queue a flush > * @bdev: blockdev to issue flush for > * @error_sector: error sector > * > * Description: > * Issue a flush for the block device in question. Caller can supply > * room for storing the error offset in case of a flush error, if they > * wish to. Caller must run wait_for_completion() on its own. > */ > > So afaict the change you've made is incomplete. We'll queue a > writeback command to the disk but we won't wait for it to be sent down > the wire. Nor do we wait for the command to complete at the device > end. So it can still be a looong time (seconds!) before the data which > the user thinks is on disk really is safe. > > Yes? > > If so, this design decision should be described in the changelog, and > justified. Actually, doing this in the comment over > ext3_blkdev_issue_flush() would be good. Actually, if sync() and fsync() do not work, it probably needs more than a comment in changelog. Like comment in documentation, in big bold letters. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html