Optimise ffs(x) by using fls(x & x - 1) which we optimise to use the SCAN
instruction.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>