Message-Id: <595CFD650200007800168BF1@prv-mh.provo.novell.com>
Date: Wed, 05 Jul 2017 06:53:25 -0600
From: "Jan Beulich" <JBeulich@suse.com>
To: "Vincent Legout" <vincent.legout@gandi.net>
Cc: "=?UTF-8?Q?Roger=20Pau=20Monn=C3=A9?=" <roger.pau@citrix.com>,
        <xen-devel@lists.xenproject.org>,
        "Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
        "Juergen Gross" <jgross@suse.com>, <linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen-blkfront: emit KOBJ_OFFLINE uevent
 when detaching device
References: <20170704114823.pvk6323gfebioikl@bres.gandi.net>
 <20170704165927.c6dgitftm4v3xk7w@dhcp-3-128.uk.xensource.com>
 <20170705080804.j6lptyhmjguhdj47@bres.gandi.net>
 <595CBCB40200007800168A16@prv-mh.provo.novell.com>
 <20170705123715.exc4qyllpxatxpnj@bres.gandi.net>
In-Reply-To: <20170705123715.exc4qyllpxatxpnj@bres.gandi.net>
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>>> On 05.07.17 at 14:37, <vincent.legout@gandi.net> wrote:
> On Wed, Jul 05, 2017 at 02:17:24AM -0600, Jan Beulich wrote :
>> >>> On 05.07.17 at 10:08, <vincent.legout@gandi.net> wrote:
>> > Without the patch, blkif_release and xlvbd_release_gendisk are never
>> > called, and no call to blk_unregister_queue is made.
>> 
>> But isn't that what needs to be fixed then? The device should be
>> removed once its last user goes away (which would be at the time
>> the umount is eventually done aiui).
> 
> You mean that block-detach should fail if the device is still mounted?
> or find a way to wait until all the users are gone?
> 
> I don't say that's not what should be done, but that's not what I get.
> The device is removed after a block-detach, even if still mounted. So
> the system is left in an unstable state without the patch.

Unstable? I'd expect subsequent I/O to fail for that device, yes, but
that's still a stable system. Are you observing anything else?

Jan