file system race condition testing

[dan carpenter <error27@email.com>]

Racer is a bunch of shell scripts that I wrote to try find race conditions in 
JFS code.  I have expanded them to be a general purpose race condition 
tester.  The scripts also found a couple bugs XFS and Reiserfs in 2.6.0-test1 
but those have been fixed in 2.6.0-test4.  

How it works is that the scripts randomly creates files 0 - 20, renames them, 
deletes them, and links to them etc.  If the filesystem survives for a couple 
hours of beating that's considerred a pass.

The scripts are at:
http://kbugs.org/racer.tar.gz

Just use `./racer.sh` to run the scripts.  Obviously, you won't want to run 
the script on a production system.

When I wrote the scripts I tried to think about all the different types of 
operations that you can do on a file but I probably missed a lot of them.  
Probably someone more familiar with filesystem code could provide useful 
feedback.

thanks,
Dan Carpenter