can't start domU after resizing zfs volume

[Michael Reifenberger]

Hi,
today I've got my first real xen dom0 error so far:

I had a 20G zfs volume with windows installed (Windows has the PV  
drivers installed).
The disk section of the cfg looks like:
...
disk =  [
         '/dev/zvol/zdata/VM/win81/root,raw,hda,rw',
         '/VM/ISO/W81.PRO.X64.MULTi8.ESD.Apr2015.iso,raw,hdc:cdrom,r'
         ]
boot="d"
...


This works until shutting down the domU and extending the volume (from  
20G) to 40G:

zfs set volsize=40G zdata/VM/win81/root

Now trying to start the guest I get:

(vm)(root) # xl create win81.cfg
Parsing config from win81.cfg
libxl: error: libxl_device.c:950:device_backend_callback: unable to  
add device with path /local/domain/0/backend/vbd/6/768
libxl: error: libxl_device.c:950:device_backend_callback: unable to  
add device with path /local/domain/0/backend/vbd/6/5632
libxl: error: libxl_create.c:1153:domcreate_launch_dm: unable to add  
disk devices
libxl: error: libxl_dm.c:1595:kill_device_model: unable to find device  
model pid in /local/domain/6/image/device-model-pid
libxl: error: libxl.c:1608:libxl__destroy_domid:  
libxl__destroy_device_model failed for 6
libxl: error: libxl_device.c:950:device_backend_callback: unable to  
remove device with path /local/domain/0/backend/vbd/6/768
libxl: error: libxl_device.c:950:device_backend_callback: unable to  
remove device with path /local/domain/0/backend/vbd/6/5632
libxl: error: libxl.c:1645:devices_destroy_cb: libxl__devices_destroy  
failed for 6
libxl: info: libxl.c:1691:devices_destroy_cb: forked pid 2306 for  
destroy of domain 6

Since I saw in syslog that GEOM did some auto-moddings of the disk I did:

`gpart commit zvol/zdata/VM/win81/root` on the dom0,
and `gpart resize -i 2 zvol/zdata/VM/win81/root`
but this didn't change the above failure.

Only after reboot the guest can be started so somewhere must be a  
mismatch of cached data...

Any clues?

Thanks in advance!

Greetings
---
Michael Reifenberger (mr @ freebsd...)





Gruß
---
Michael Reifenberger