[PVE-User] resize2fs not works

[Charles Bijon]

Hi,

I need to make some partition modifications without reboot my server. 
But when i try to do an :

root at sgp2605:/# resize2fs /dev/mapper/pve-root 20G
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/pve-root is mounted on /; on-line resizing 
required
resize2fs: On-line shrinking not supported

This is not possible, why ? How i can force it ?

I have other debian server with lvm ( without promox ) and i can do this 
easly, without umount the partition.

Regards,

Charles