Xen: how do i alert a domU to an lvresize on dom0?

I have a simple Xen setup with two domains, a dom0 and a domU. The physical disks are handled by LVM in the dom0, and certain logical volumes from the dom0 are exported to the domU as /dev/sda1, etc.

If i resize one of the logical volumes from the dom0, how can i convince the domU to learn of the change in the underlying size? Is it possible to do this without restarting the domU? I haven't had any luck searching the 'net.

On the domU,i saw that the block device in question is 10G:

0 domU:~# cat /proc/partitions major minor  #blocks  name   8     1   10485760 sda1   8     2     524288 sda2   8     3   10485760 sda3 253     0   10485244 dm-00 domU:~#

and on the dom0, i check that it looks right, and then lvresize it:

0 dom0:~# lvs  LV         VG   Attr   LSize   Origin Snap%  Move Log Copy%   domU-disk  vg0  -wi-ao  10.00G                                domU-srv   vg0  -wi-ao  10.00G                                domU-swap  vg0  -wi-ao 512.00M                                dom0       vg0  -wi-ao   1.00G                              0 dom0:~# lvresize --size +2G vg0/domU-srv  Extending logical volume domU-srv to 12.00 GB  Logical volume domU-srv successfully resized0 dom0:~#

but domU:/proc/partitions still looks the same. I've tried installing hdparm on the domU and creating a fake /dev/sda for it to "re-read the partition table from", but that didn't work:

0 domU:~# mknod /dev/sda b 8 10 domU:~# hdparm -z /dev/sda/dev/sda: BLKRRPART failed: Invalid argument0 domU:~# cat /proc/partitions major minor  #blocks  name   8     1   10485760 sda1   8     2     524288 sda2   8     3   10485760 sda3 253     0   10485244 dm-00 domU:~#

any suggestions for what else i should try? Is there a xen-specific command to alert the domU of such a change?

Tags: lvm, xen