linux-kernel - Re: [Xen-devel] [PATCH 1/2] xen-blkfront: don't call talk_to_blkback when already connected to blkback

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Message-ID: <57611424.2020802@citrix.com>
Date:	Wed, 15 Jun 2016 09:39:00 +0100
From:	Ross Lagerwall <ross.lagerwall@...rix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Bob Liu <bob.liu@...cle.com>
CC:	<xen-devel@...ts.xenproject.org>, <linux-kernel@...r.kernel.org>,
	<roger.pau@...rix.com>
Subject: Re: [Xen-devel] [PATCH 1/2] xen-blkfront: don't call talk_to_blkback
 when already connected to blkback

On 06/08/2016 03:47 PM, Konrad Rzeszutek Wilk wrote:
> On Wed, Jun 08, 2016 at 02:46:38PM +0800, Bob Liu wrote:
>>
>> On 06/07/2016 11:25 PM, Konrad Rzeszutek Wilk wrote:
>>> On Wed, Jun 01, 2016 at 01:49:23PM +0800, Bob Liu wrote:
>>>>
>>>> On 06/01/2016 04:33 AM, Konrad Rzeszutek Wilk wrote:
>>>>> On Tue, May 31, 2016 at 04:59:16PM +0800, Bob Liu wrote:
>>>>>> Sometimes blkfont may receive twice blkback_changed() notification after
>>>>>> migration, then talk_to_blkback() will be called twice too and confused
>>>>>> xen-blkback.
>>>>>
... snip
>>>> But sometimes blkfront receives
>>>> blkback_changed() event more than once!
>>>
>>> I think I know why. The udev scripts that get invoked when when
>>> we attach a disk are a bit custom. As such I think they just
>>> revalidate the size leading to this.
>>>
>>> And this 'poke-at-XenbusStateConnected' state multiple times
>>> is allowed. It is used to signal disk changes (or just to revalidate).
>>> Hence it does not matter why really - we need to deal with this.
>>>
>>> I modified your patch a bit and are testing it:
>>>
>>
>> Looks much better, thank you very much!
>
> Great! I also had it tested overnight and there was no hitch will send it
> out soon.
>

I'd like to request that this patch is backported to Linux 4.5 and both 
of the patches in this series are backported to Linux 4.6. This is 
affecting Debian Testing (using Linux 4.6). It fails to recover its disk 
when resuming or migrating.

Thanks,
-- 
Ross Lagerwall