From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: Re: [PATCH] xen/blkback: add xen-blkback support
Date: Mon, 18 Apr 2011 16:14:43 -0400
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> > Hmm, let me remove those get/puts. They are actually not necessary as we
> > already hold a reference count when we opened the device.
> 
> Ack. I never noticed these weren't exported. 
> 
> But bdev_get_queue is not an addref, just an accessor macro, as you're
> probably aware of. 

Yes.
> 
> But get/put is normally managed entirely in block/ and implied by the
> request and bdev interfaces.

And I found the reason for all of that. Way back in the past (2.6.18)
we would be checking the request_queue->flag to make sure it did not have
the QUEUE_FLAG_DEAD flag set. Over the years the block API started doing that
in the submit_bio path and .. well, we don't need this check anymore.