linux-kernel - Re: [PATCH 4/4] xen-blkback: support dynamic unbind/bind

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Message-ID: <20191209121726.GU980@Air-de-Roger>
Date:   Mon, 9 Dec 2019 13:17:26 +0100
From:   Roger Pau Monné <roger.pau@...rix.com>
To:     Paul Durrant <pdurrant@...zon.com>
CC:     <linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        Jens Axboe <axboe@...nel.dk>,
        "Boris Ostrovsky" <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>
Subject: Re: [PATCH 4/4] xen-blkback: support dynamic unbind/bind

On Thu, Dec 05, 2019 at 02:01:23PM +0000, Paul Durrant wrote:
> By simply re-attaching to shared rings during connect_ring() rather than
> assuming they are freshly allocated (i.e assuming the counters are zero)
> it is possible for vbd instances to be unbound and re-bound from and to
> (respectively) a running guest.
> 
> This has been tested by running:
> 
> while true; do dd if=/dev/urandom of=test.img bs=1M count=1024; done
> 
> in a PV guest whilst running:
> 
> while true;
>   do echo vbd-$DOMID-$VBD >unbind;
>   echo unbound;
>   sleep 5;
>   echo vbd-$DOMID-$VBD >bind;
>   echo bound;
>   sleep 3;
>   done

So this does unbind blkback while leaving the PV interface as
connected?

Thanks, Roger.