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Date: Tue, 19 Jun 2012 13:29:55 +0200
From: Spelic <spelic@shiftmail.org>
Subject: Re: Ext4 and xfs problems in dm-thin on allocation and discard
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To: =?windows-1252?Q?Luk=E1=9A_Czerner?= <lczerner@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>, xfs@oss.sgi.com, device-mapper development <dm-devel@redhat.com>, Spelic <spelic@shiftmail.org>, linux-ext4@vger.kernel.org

On 06/19/12 08:32, Luk=E1=9A Czerner wrote:
>
> So do I understand correctly that even though the discard came
> through and thinp took advantage of it it still returns EOPNOTSUPP ?
> This seems rather suboptimal. IIRC there was a discussion to add an
> option to enable/disable sending discard in thinp target down
> to the device.

I'll ask this too...
do I understand correctly that dm-thin returns EOPNOTSUPP to the =

filesystem layer even though it is using the discard to unmap blocks, =

and at that point XFS stops sending discards down there (while ext4 =

keeps sending them)?

This looks like a bug of dm-thin to me. Discards are "supported" in such =

a scenario.

Do you have a patch for dm-thin so to prevent it sending EOPTNOTSUPP ?

Thank you
S.

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