From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Omar Sandoval <osandov@osandov.com>
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: FIDEDUPERANGE with src_length == 0
Date: Tue, 12 Jul 2016 22:26:43 -0700 [thread overview]
Message-ID: <20160713052643.GD13625@birch.djwong.org> (raw)
In-Reply-To: <20160712003537.GA27653@vader.dhcp.thefacebook.com>
On Mon, Jul 11, 2016 at 05:35:37PM -0700, Omar Sandoval wrote:
> Hey, Darrick,
>
> generic/182 is failing on Btrfs for me with the following output:
>
> --- tests/generic/182.out 2016-07-07 19:51:54.000000000 -0700
> +++ /tmp/fixxfstests/xfstests/results//generic/182.out.bad 2016-07-11 17:28:28.230039216 -0700
> @@ -1,12 +1,10 @@
> QA output created by 182
> Create the original files
> -dedupe: Extents did not match.
> f4820540fc0ac02750739896fe028d56 TEST_DIR/test-182/file1
> 69ad53078a16243d98e21d9f8704a071 TEST_DIR/test-182/file2
> 69ad53078a16243d98e21d9f8704a071 TEST_DIR/test-182/file2.chk
> Compare against check files
> Make the original file almost dedup-able
> -dedupe: Extents did not match.
> f4820540fc0ac02750739896fe028d56 TEST_DIR/test-182/file1
> 158d4e3578b94b89cbb44493a2110fb9 TEST_DIR/test-182/file2
> 158d4e3578b94b89cbb44493a2110fb9 TEST_DIR/test-182/file2.chk
>
> It looks like that test is checking that a dedupe with length == 0 is
> treated as a dedupe to EOF, but Btrfs doesn't do that [1]. As far as I
> can tell, it never did, but maybe I'm just confused. What was the
> behavior when you introduced that test? That seems like a reasonable
> thing to do, but I wanted to clear this up before changing/fixing Btrfs.
It's a shortcut that we're introducing in the upcoming XFS implementation,
since it shares the same back end as clone/clonerange, which both have
this behavior.
--D
>
> Thanks.
>
> 1: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/fs/btrfs/ioctl.c?h=v4.7-rc7#n3122
> --
> Omar
next prev parent reply other threads:[~2016-07-13 5:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-12 0:35 FIDEDUPERANGE with src_length == 0 Omar Sandoval
2016-07-13 5:26 ` Darrick J. Wong [this message]
2016-07-13 13:19 ` David Sterba
2016-07-14 18:06 ` Darrick J. Wong
2016-07-14 18:12 ` Chris Mason
2016-07-14 18:16 ` Omar Sandoval
2016-07-15 16:54 ` Darrick J. Wong
2016-08-01 19:32 ` Darrick J. Wong
2016-07-14 2:47 ` Christoph Hellwig
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