resizing a ext3 disk image

Took me a while to figure this out, so thought I'd put it here for others. This is useful for Xen setups, where you use a file for the disk image. AFAIK, you can only grow an image, not shrink it.

# dd if=/dev/zero bs=1M count=1024 >> disk.img
# e2fsck -f disk.img
# resize2fs disk.img
# e2fsck -f disk.img

This makes the disk image bigger, checks the image, resizes the file system, and then checks it again