Ricardo and I developed a Linux kernel module to do tracing of block layer I/Os. I would appreciate if you can install this on your machine so we could collect traces as well as testing the module. I have been tracing my machine and doomsday for a couple of days now with no problems.
This will only work for Ubuntu. I've only tested for 10.04 (my machine) and 8.04 (doomsday).
You just have to download the script install_tracing.sh and run it as root.
If you find any problem, send me an email with the error luis@cs.fiu.edu.