From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH] Use queuedata accessors for device handler
Date: Mon, 22 Aug 2011 10:45:05 -0400
Message-ID: <20110822144505.GA5705@infradead.org>
References: <201108221335.p7MDZhBm013520@pentland.suse.de>
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To: Hannes Reinecke <hare@suse.de>
Cc: James Bottomley <James.Bottomley@parallels.com>, linux-scsi@vger.kernel.org

On Mon, Aug 22, 2011 at 03:35:43PM +0200, Hannes Reinecke wrote:
> 
> Starting multipath on a cciss device will cause a kernel
> warning to be triggered. Problem is that we're using the
> ->queuedata field of the request_queue to dereference the
> scsi device; however, for other (non-SCSI) devices this
> points to a totally different structure.
> So we should rather be using accessors here to make
> sure ->queuedata points to a valid sdev.

How do we match to attach a scsi device handler to a non-scsi queue?
I suspect that is the fundamental issue that needs addressing.