From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: qdisk vs. file as vbd type
Date: Fri, 10 Jan 2014 16:19:56 +0100
Message-ID: <20140110151956.GA22646@aepfle.de>
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	<20140110150000.GA20287@aepfle.de>
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To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>, xen-devel@lists.xen.org
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[ removing Li who is no longer with Novell ]

On Fri, Jan 10, Konrad Rzeszutek Wilk wrote:

> You are looking at:
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1664)   } else if (strncmp(type, "file", 4) == 0)
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1665)           info->feature_discard = 1;
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1666)
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1667)   kfree(type);
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1668)}
> ed30bf317       (Li Dongyang    2011-09-01 18:39:09 +0800       1669)
> 
> My recollection is that at the time the patches were developed, loop
> was not able to do discard operations. That has since changed and
> loop can do it. Hence the force of =1 was added in.

If the backend cant do discard then it should not advertise the feature.

Are you ok with me sending a patch which simplifies this function?

Olaf