From: Christoph Hellwig <hch@lst.de>

To be useful for distribution kernels it needs to be a runtime option.
The original patch is from Joerg Platte via the Debian kernel package,
with some adjustments from me (and me too - Bart).
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@elka.pw.edu.pl>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>