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?
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]
Destroy a domain's virtual block device.
[root@tst009 ~]# xm block-detach 6 51712 -f
> 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?
>
> 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);
> --
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