Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754394AbZALPL7 (ORCPT ); Mon, 12 Jan 2009 10:11:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751571AbZALPLu (ORCPT ); Mon, 12 Jan 2009 10:11:50 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:46152 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751096AbZALPLu (ORCPT ); Mon, 12 Jan 2009 10:11:50 -0500 Date: Mon, 12 Jan 2009 10:11:33 -0500 From: Christoph Hellwig To: Mikulas Patocka Cc: xfs@oss.sgi.com, linux-kernel@vger.kernel.org Subject: Re: spurious -ENOSPC on XFS Message-ID: <20090112151133.GA24852@infradead.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1452 Lines: 29 On Mon, Jan 12, 2009 at 06:14:36AM -0500, Mikulas Patocka wrote: > Hi > > I discovered a bug in XFS in delayed allocation. > > When you take a small partition (52MB in my case) and copy many small > files on it (source code) that barely fits there, you get -ENOSPC. Then > sync the partition, some free space pops up, click "retry" in MC an the > copy continues. They you get again -ENOSPC, you must sync, click "retry" > and go on. And so on few times until the source code finally fits on the > XFS partition. > > This misbehavior is apparently caused by delayed allocation, delayed > allocation does not exactly know how much space will be occupied by data, > so it makes some upper bound guess. Because free space count is only a > guess, not the actual data being consumed, XFS should not return -ENOSPC > on behalf of it. When the free space overflows, XFS should sync itself, > retry allocation and only return -ENOSPC if it fails the second time, > after the sync. This looks a lot like: http://oss.sgi.com/bugzilla/show_bug.cgi?id=724 It's on my short-term todo list to turn the testcase in that entry into a proper xfsqa testcase and followup on the investigation by Dave and Eric. -- 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/