mm: use roundown_pow_of_two() in zone_batchsize()

Use roundown_pow_of_two(N) in zone_batchsize() rather than (1 <<
(fls(N)-1)) as they are equivalent, and with the former it is easier to
see what is going on.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Lanttor Guo <lanttor.guo@freescale.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e2f2699..8add7da 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2706,7 +2706,7 @@ static int zone_batchsize(struct zone *zone)
         * of pages of one half of the possible page colors
         * and the other with pages of the other colors.
         */
-       batch = (1 << (fls(batch + batch/2)-1)) - 1;
+       batch = rounddown_pow_of_two(batch + batch/2) - 1;
 
        return batch;
 }