From: Eric Sandeen <sandeen@sandeen.net>
To: Sean Noonan <Sean.Noonan@twosigma.com>
Cc: "'linux-xfs@oss.sgi.com'" <linux-xfs@oss.sgi.com>,
Martin Bligh <Martin.Bligh@twosigma.com>,
Stephen Degler <Stephen.Degler@twosigma.com>,
Ian Baum <Ian.Baum@twosigma.com>,
Trammell Hudson <Trammell.Hudson@twosigma.com>
Subject: Re: sparse file handling bug in XFS
Date: Thu, 16 Jun 2011 11:08:22 -0500 [thread overview]
Message-ID: <4DFA2A76.6000104@sandeen.net> (raw)
In-Reply-To: <081DDE43F61F3D43929A181B477DCA95639B561F@MSXAOA6.twosigma.com>
On 6/16/11 9:49 AM, Sean Noonan wrote:
> Sparse files do not stay sparse.
> Here's the simplest test case I've got so far. I don't think it can get much simpler than this.
>
> This did not exist in 2.6.36. It appeared by 2.6.38-rc8. It continued into 2.6.38.2. It continues to exist on 3.0.0-rc3.
>
> # for x in gogo xfs; do date | dd of=sparse-file bs=1k seek=4096; stat sparse-file; done
Funky; if we do xfs_bmap, it shows the right nr of blocks allocated:
# for x in gogo xfs; do date | dd of=sparse-file bs=1k seek=4096; stat sparse-file | grep Blocks; xfs_bmap -v sparse-file; done
Size: 4194333 Blocks: 8 IO Block: 4096 regular file
sparse-file:
EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL
0: [0..8191]: hole 8192
1: [8192..8199]: 450475168..450475175 2 (18736320..18736327) 8
Size: 4194333 Blocks: 8192 IO Block: 4096 regular file
sparse-file:
EXT: FILE-OFFSET BLOCK-RANGE AG AG-OFFSET TOTAL
0: [0..8191]: hole 8192
1: [8192..8199]: 459367952..459367959 2 (27629104..27629111) 8
And if we unmount & remount it's right again:
# stat sparse-file | grep Blocks
Size: 4194333 Blocks: 8 IO Block: 4096 regular file
so they do remain sparse, but stat tells us the wrong thing. I think it has
to do with the count of delayed blocks but I'll try to look into it.
-Eric
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next prev parent reply other threads:[~2011-06-16 16:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-16 14:49 sparse file handling bug in XFS Sean Noonan
2011-06-16 16:08 ` Eric Sandeen [this message]
2011-06-16 17:33 ` Eric Sandeen
2011-06-16 17:57 ` Christoph Hellwig
2011-06-16 21:08 ` Eric Sandeen
2011-06-19 22:27 ` Dave Chinner
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