Reorder test_root testing from 3,5,7 to 7,5,3 so that average case becomes
good.  Even number check is added.  
Signed-off-by: Prasanna Meda <pmeda@akamai.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>