In-place Resize of Wubi virtual disk
This document describes how to resize a Wubi virtual disk. There are two distinct techniques.
The technique described here is a true resize of the virtual disk (root.disk), and must be performed from a live CD. This is very fast and can also make better use of the available space on the host partition, than the alternate method, which duplicates the virtual disk. However the duplication doesn't require a live CD, and also leaves you with a full backup. See here for further details.
CREDIT... Thanks to Trooper_Max for suggesting this
1. You have to boot from a live CD/USB. This won't work while running Wubi.
2. Backup the root.disk (not required, but a good idea)
3. Mount the NTFS partition that your root.disk is on (this example assumes it's /dev/sda1 and the mountpoint is /media/win - adjust accordingly in the following instructions):
sudo mkdir -p /media/win sudo mount /dev/sda1 /media/win
4. Check the size of the root.disk (not required)
du -h --apparent-size /media/win/ubuntu/disks/root.disk
5. Run fsck on the root.disk
fsck -f /media/win/ubuntu/disks/root.disk
6. Resize - specify the desired final size (this example resizes to 10 GB)
resize2fs /media/win/ubuntu/disks/root.disk 10G
7. Reboot back into Wubi Ubuntu