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Date:   Fri, 7 Sep 2018 09:54:55 +0200
From:   Roger Pau =?utf-8?B?TW9ubsOp?= <roger.pau@citrix.com>
To:     Valentin Vidic <Valentin.Vidic@CARNet.hr>
CC:     Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Jens Axboe <axboe@kernel.dk>, <xen-devel@lists.xenproject.org>,
        <linux-block@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <stable@vger.kernel.org>, <drbd-user@lists.linbit.com>
Subject: Re: [PATCH] xen-blkback: Switch to closed state after releasing the
 backing device
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On Fri, Sep 07, 2018 at 09:23:19AM +0200, Valentin Vidic wrote:
> On Fri, Sep 07, 2018 at 09:15:30AM +0200, Roger Pau Monn? wrote:
> > I'm not sure that's a good idea, there are a lot of backends (apart
> > from blkback), and the tools won't know whether a specific backend
> > supports such state or not. Also the current protocol and states are
> > shared between all the Xen PV devices, so new additions should be
> > considered very carefully.
> 
> Sure, I understand.
> 
> > IMO the best options are either calling vbd_free/vbd_create at proper
> > stages in blkback or changing the hotplug script so it waits for the
> > device to have no open clients.
> 
> Changing the block-drbd script would be ideal for me too, but I don't
> think that piece of DRBD state is exposed at the moment.

Then I'm afraid you will have to look into the vbd_free/create fix.

Thanks, Roger.