Ok guys i found an easy way around for my previous post!

The bug is actualy in the xen-tools config file! When you edit it just make sure that you edit the line saing 'reiser_options=defaults' to 'reiserfs_options=defaults' in /etc/xen-tools/xen-tools.conf. That will set the proper options in the fstab of the VMachine.

You can change 'defaults' to whatever options for reiserfs you like. In my case 'notail,relatime' works fine!!