Last year’s FOSS.IN had a Kernel Workout session, in which i participated and tried to do a task titled ‘implement XFS preallocation ioctls in the VFS’.
Christoph Hellwig helped me understand the problem and I had a preliminary patch ready in the session, which was improved later over email with his and Hari’s help and finally got merged into 2.6.31-rc1 
Here is the patch.
Thanks to FOSS.IN for this opportunity, and thanks to my friends for their support and encouragement 
Hopefully, this wont be the last 
