Live disk resize

Hi all, I have a cloudmin 1.820 installation on a debian jessie.

A guest has a 200G disk.

It’s a logical volume (lvm).
What’s going to happen if I change (increase) the field ‘Disk file size’ without shutting down the guest?

The guest is another debian jessie and the vdi has a single partition

parted /dev/vda print Model: Virtio Block Device (virtblk) Disk /dev/vda: 215GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags:

Number Start End Size Type File system Flags
1 1049kB 215GB 215GB primary ext4 boot

I don’t believe anything will happen. It can’t resize without a reboot (I think you could resize the volume and then login and resize it manually in some cases, but I doubt that’d work for the boot partition…ext4 has to be unmounted to resize, I’m pretty sure).