Simulate Out Of Disk condition for a test (Linux)

We recently had a problem in production where a service was filling up the disk, happily swallowing the IOException that was thrown, and continuing on its merry and error prone way. Needless to say, it emptied the input (a high volume redis queue) and produced garbage. We fixed this and then before deployment, needed to create an Out of Disk scenario for testing. My first, clumsy attempt was to fill the disk with the dd command but a few hours later felt very sheepish, as it took quite a while to fill up a large disk (more than half a Terrabyte). The easiest way to do this is to create a loopback partition of a fixed size. Here are the steps I used :

mkdir /filesystems
dd if=/dev/zero of=/filesystems/tmp_fs seek=512 count=512 bs=1M
mkfs.ext4 /filesystems/tmp_fs
mkdir /mnt/small
mount -o loop /filesystems/tmp_fs /mnt/small

This creates a partition of about 1G that gets mounted to /mnt/small. In our scenario, we had to create the Lucene index inside this directory.