From: "Martin K. Petersen" <martin.petersen@oracle.com>
Subject: Re: do not disable ext4 discards on first discard
	failure? [was: Re: dm snapshot: ignore discards issued to the
	snapshot-origin target]
Date: Mon, 02 May 2011 10:20:54 -0400
Message-ID: <yq1bozl420p.fsf@sermon.lab.mkp.net>
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	<20110429122454.GL32370@agk-dp.fab.redhat.com>
	<alpine.LFD.2.00.1105020857030.3778@dhcp-27-109.brq.redhat.com>
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Cc: sandeen@redhat.com, Mike Snitzer <snitzer@redhat.com>,
        Christoph Hellwig <hch@infradead.org>,
        device-mapper development <dm-devel@redhat.com>,
        DarkNovaNick@gmail.com, linux-lvm@redhat.com,
        linux-ext4@vger.kernel.org, Alasdair G Kergon <agk@redhat.com>
To: Lukas Czerner <lczerner@redhat.com>
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In-Reply-To: <alpine.LFD.2.00.1105021217080.3778@dhcp-27-109.brq.redhat.com>
	(Lukas Czerner's message of "Mon, 2 May 2011 12:24:33 +0200 (CEST)")
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>>>>> "Lukas" == Lukas Czerner <lczerner@redhat.com> writes:

Lukas> So I gave it a try. First of all the device composed of SSD and
Lukas> spinning disk does export discard_support information properly,
Lukas> however it also advertise discard_zeroes_data which is wrong and
Lukas> possibly dangerous and should be fixed!

I can't reproduce this here. If I mix discard and non-discard devices
things work correctly. discard_zeroes_data also gets cleared if I mix
discard-capable drives where one zeroes and one doesn't.

-- 
Martin K. Petersen	Oracle Linux Engineering