Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757760AbYLDWEw (ORCPT ); Thu, 4 Dec 2008 17:04:52 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755883AbYLDWEn (ORCPT ); Thu, 4 Dec 2008 17:04:43 -0500 Received: from one.firstfloor.org ([213.235.205.2]:46367 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755839AbYLDWEm (ORCPT ); Thu, 4 Dec 2008 17:04:42 -0500 Date: Thu, 4 Dec 2008 23:15:51 +0100 From: Andi Kleen To: Mikulas Patocka Cc: Andi Kleen , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, Alasdair G Kergon , Andi Kleen , Milan Broz Subject: Re: Device loses barrier support (was: Fixed patch for simple barriers.) Message-ID: <20081204221551.GV6703@one.firstfloor.org> References: <20081204100050.GN6703@one.firstfloor.org> <20081204142015.GQ6703@one.firstfloor.org> <20081204145810.GR6703@one.firstfloor.org> <20081204174838.GS6703@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1142 Lines: 26 > If you are pushing what you are pushing --- barriers allowing to return > EOPNOTSUPP anytime --- then asynchronous barrier submits can no longer be > used, because by the time EOPNOTSUPP is detected, the filesystem is > already corrupted. Chris Mason pointed out that this can actually already happen. From a quick review this can happen in MD raid1 at least (their barriers_work flag is pretty similar to the DM implementation I did). So everyone has to handle this already anyways. > I'm wondering, where in fsync() does Linux wait for hardware disk cache to > be flushed? Isn't there a bug that fsync() will return before the cache is > flushed? I couldn't really find it. The last thing do_fsync calls is > filemap_fdatawait and it doesn't do cache flush (blkdev_issue_flush). At least in fsync() on journaling fs the metadata update should push it. -Andi -- ak@linux.intel.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/