linux-kernel - Re: xen-blkfront: Don't send closing notification to backend in blkfront

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Message-ID: <4E1BBFFD.7030900@oracle.com>
Date:	Tue, 12 Jul 2011 11:31:09 +0800
From:	Joe Jin <joe.jin@...cle.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Daniel Stodden <daniel.stodden@...rix.com>,
	Jens Axboe <jaxboe@...ionio.com>, annie.li@...cle.com,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	Ian Campbell <ian.campbell@...rix.com>,
	Kurt C Hackel <KURT.HACKEL@...cle.com>,
	Greg Marsden <greg.marsden@...cle.com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: xen-blkfront: Don't send closing  notification to backend in
 blkfront_closing()

On 07/09/11 21:11, Konrad Rzeszutek Wilk wrote:
>>>> 5. umount the partition/disk in guest, command hung. exactly at here, any
>>>>    IO request to the partition/disk will hang.
>>>
>>> I get that with the patch and without it:
>>>
>>> sh-4.1#
>>> sh-4.1# [  519.814048] block xvda: device/vbd/51712 was hot-unplugged, 1 stale handles
>>>
>>> sh-4.1# df -h
>>> Filesystem            Size  Used Avail Use% Mounted on
>>> none                  490M  120K  490M   1% /dev
>>> none                  490M  131M  359M  27% /lib/modules/3.0.0-rc6-00052-g3edce4b-dirty
>>> shm                    10M     0   10M   0% /dev/shm
>>> var_tmp                10M     0   10M   0% /var/tmp
>>> /dev/xvda              20G  173M   19G   1% /test
>>> sh-4.1# umount /test
>>>
>>> Any ideas?
>>
>> This caused by backend kthread stopped, any IO request to the real device will hang, that
>> is the patch intend to resolving.
> 
> I get this hang with the patch (and without). Is there a corresponding patch to the backend?
> (The backend is the same exact version as DomU - 3.0-rc6 + #stable/for-jens).

I tried xen and linux the latest code, 
# xm dmesg | grep "Xen version"
(XEN) Xen version 4.2-unstable (root@...oracle.com) () Tue Jul 12 06:51:41 CST 2011

Dom0:
# uname -r
3.0.0-rc6-XYZxen

Guest
# uname -r
3.0.0-rc6-XYZxen

without the patch, after detach the device by xm block-detach timeout also umount hang in guest.
with my patch, xm block-detach timeout in Dom0, umount in guest worked!

Thanks,
Joe


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