Konrad,
Thanks for the reply, see comments in lines.
On 07/09/11 00:04, Konrad Rzeszutek Wilk wrote:
> On Fri, Jul 08, 2011 at 03:14:29PM +0800, Joe Jin wrote:
>> When we do block attach detach test with below steps, umount hang and the
>> guest unable to shutdown:
>>
>> 1. start guest with the latest kernel.
>> 2. attach new disk by xm-attach in Dom0
>> 3. mount new disk in guest
>> 4. detach the disk by xm-detach in dom0
>
> I think you mean xm block-detach and xm-attach?
You are right and sorry for confusing.
>
> I tried with and without your patch and in both cases I get
> this in my guest:
>
> sh-4.1# mount /dev/xvda /test
> [ 385.949749] EXT3-fs: barriers not enabled
> [ 385.960173] kjournald starting. Commit interval 5 seconds
> [ 385.960418] EXT3-fs (xvda): using internal journal
> [ 385.960427] EXT3-fs (xvda): mounted filesystem with writeback data mode
> sh-4.1# [ 411.176887] vbd vbd-51712: 16 Device in use; refusing to close
>
> The commands on the other side (Dom0) were:
>
> [root@tst009 ~]# xm block-list 6
> Vdev BE handle state evt-ch ring-ref BE-path
> 51712 0 0 4 12 770 /local/domain/0/backend/vbd/6/51712
> [root@tst009 ~]# xm block-detach 6 51712
> Error: Device 51712 (vbd) could not be disconnected.
> Usage: xm block-detach <Domain> <DevId> [-f|--force]
>
The error caused by xm block-detach timeout to waiting the dev's state switch
to Closed.
> Destroy a domain's virtual block device.
> [root@tst009 ~]# xm block-detach 6 51712 -f
>
With "--force", it always success but frontend did not disconnected if device
opened by someone.
>
>> 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.
Thanks,
Joe
>>
>> Checking the code we found when xm-detach command set backend state to
>> Closing, will trigger blkback_changed() -> blkfront_closing() call.
>> At the moment, the disk still opened by guest, so frontend will refuse the
>> request, but in the blkfront_closing(), it send a notification to backend
>> said that the frontend state switched to Closing, when backend got the
>> event, it will disconnect from real device, at here any IO request will
>> be stuck, even tried to release the disk by umount.
>>
>> Per our test, below patch fix this issue.
>>
>> Signed-off-by: Joe Jin <joe.jin@xxxxxxxxxx>
>> Signed-off-by: Annie Li <annie.li@xxxxxxxxxx>
>> ---
>> xen-blkfront.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>> index b536a9c..f6d8ac2 100644
>> --- a/drivers/block/xen-blkfront.c
>> +++ b/drivers/block/xen-blkfront.c
>> @@ -1088,7 +1088,7 @@ blkfront_closing(struct blkfront_info *info)
>> if (bdev->bd_openers) {
>> xenbus_dev_error(xbdev, -EBUSY,
>> "Device in use; refusing to close");
>> - xenbus_switch_state(xbdev, XenbusStateClosing);
>> + xbdev->state = XenbusStateClosing;
>> } else {
>> xlvbd_release_gendisk(info);
>> xenbus_frontend_closed(xbdev);
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home