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From: Christoph Hellwig <hch@infradead.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: linux-kernel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: spurious -ENOSPC on XFS
Date: Mon, 12 Jan 2009 10:11:33 -0500	[thread overview]
Message-ID: <20090112151133.GA24852@infradead.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0901120509550.11089@hs20-bc2-1.build.redhat.com>

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.

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  reply	other threads:[~2009-01-12 15:12 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-12 11:14 spurious -ENOSPC on XFS Mikulas Patocka
2009-01-12 15:11 ` Christoph Hellwig [this message]
2009-01-13  5:58   ` Lachlan McIlroy
2009-01-14 22:16     ` Dave Chinner
2009-01-15  0:57       ` Lachlan McIlroy
2009-01-15  8:47         ` Dave Chinner
2009-01-13 21:49 ` Dave Chinner
2009-01-14  4:28   ` Mikulas Patocka
2009-01-18 17:31     ` Christoph Hellwig
2009-01-20 19:38       ` Mikulas Patocka
2009-01-20 23:24         ` Dave Chinner
2009-01-22 20:59           ` Christoph Hellwig
2009-01-22 22:43             ` Christoph Hellwig
2009-01-23 20:14               ` Mikulas Patocka
2009-01-24  7:12                 ` Dave Chinner
2009-01-29 16:39                   ` Mikulas Patocka
2009-01-29 16:45                     ` Mikulas Patocka
2009-01-31 23:57                     ` Dave Chinner
2009-02-02 17:36                       ` Mikulas Patocka
2009-02-03  3:27                         ` Dave Chinner
2009-02-03 20:05                           ` Mikulas Patocka
2009-02-04 12:08                             ` Dave Chinner
2009-02-05  4:31                               ` Mikulas Patocka
2009-02-05  7:43                                 ` Dave Chinner

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