From: Eric Sandeen Subject: Re: [PATCH V2] xfstests: make 275 pass Date: Tue, 17 Jan 2012 10:33:20 -0600 Message-ID: <4F15A2D0.2090900@sandeen.net> References: <4F04A6E6.1090304@redhat.com> <4F04BC81.1000207@redhat.com> <20120104231725.GB24466@dastard> <4F04DEDC.6020807@redhat.com> <20120105003928.GC24466@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Eric Sandeen , ext4 development , Eryu Guan , xfs-oss To: Dave Chinner Return-path: Received: from sandeen.net ([63.231.237.45]:47196 "EHLO mail.sandeen.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755009Ab2AQQdT (ORCPT ); Tue, 17 Jan 2012 11:33:19 -0500 In-Reply-To: <20120105003928.GC24466@dastard> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 1/4/12 6:39 PM, Dave Chinner wrote: > On Wed, Jan 04, 2012 at 05:21:00PM -0600, Eric Sandeen wrote: >> On 1/4/12 5:17 PM, Dave Chinner wrote: >>> On Wed, Jan 04, 2012 at 02:54:25PM -0600, Eric Sandeen wrote: >>>> Ok, this is a significant rework of 275, which made too many >>>> assumptions about details of space usage and failed on several >>>> filesystems (it passed on xfs, but only by accident). >>>> >>>> This new version tries to leave about 256k free, then tries >>>> a single 1M IO, and fails only if 0 bytes are written. >>>> >>>> It also sends a lot more to $seq.full for debugging on failure >>>> and fixes a few other stylistic things. >>>> >>>> Signed-off-by: Eric Sandeen >>> >>> I just had another thought about this, Eric.... >>> >>>> +# And at least some of it should succeed. >>>> +_filesize=`du $SCRATCH_MNT/tmp1 | awk '{print $1}'` >>>> +[ $_filesize -eq 0 ] && _fail "write file err: Partial write until enospc failed; wrote 0 bytes." >>> >>> The question that just came to mind was this assumes that allocation >>> succeeded so therefore the partial write succeeded. But that's not >>> necessary the case. The partial write might not succeed leaving the >>> file size as zero, but the underlying FS might not remove all the >>> blocks it allocated (nothing says that it has to). Hence to >>> determine if a partial write succeeded, we also need to check that >>> the file size itself is greater than zero.... >> >> Probably need to read up on what posix says it should do. I think >> what you're saying is that it might leave blocks allocated past EOF? >> That'd be surprising to me, but maybe I misunderstand? > > There's no guarantee that du is even reporting blocks on disk. e.g > for XFS du will also report reserved (in-memory) delalloc space on > the inode and that includes speculative allocation beyond EOF. We > don't have to remove specultive delalloc ranges when a partial write > occurs, so effectively checking du output to see if a partial write > succeeded is not a sufficient test to determine if the partial write > succeeded or not. > > However, if the partial write did succeed then the file size *must* > change to reflect what was written. Hence I suspect all we actually > need here is a file size check... Ok; so would you be happy with just this? # And at least some of it should succeed. _filesize=`ls -l $SCRATCH_MNT/tmp1 | awk '{print $5}'` [ $_filesize -eq 0 ] && _fail "write file err: Partial write until enospc failed; wrote 0 bytes." If so I'll put your reviewed-by on it and get this pushed, ok? -Eric > Cheers, > > Dave.