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

From: Ross Lagerwall
Date: Wed Jun 15 2016 - 04:39:10 EST


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