[dm-devel] [PATCH] dm-raid: fix default region size

[Mikulas Patocka]

The commit 3a0f9aaee02857609d79b20c809c02a8b7c39d06 should make sure that
the default region size is a power of two. However, the logic is incorrect
and sets the variable region_size to 0 or 1, depending on whether
min_region_size is a power of two.

This patch fixes the logic, so that region_size is set to min_region_size
rounded up to the next power of two.

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>
Fixes: 3a0f9aaee028 ("dm raid: round region_size to power of two")
Cc: stable at vger.kernel.org	# v3.8+

---
 drivers/md/dm-raid.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Index: linux-4.3-rc3/drivers/md/dm-raid.c
===================================================================
--- linux-4.3-rc3.orig/drivers/md/dm-raid.c	2015-10-02 15:20:04.000000000 +0200
+++ linux-4.3-rc3/drivers/md/dm-raid.c	2015-10-02 15:29:34.000000000 +0200
@@ -329,8 +329,7 @@ static int validate_region_size(struct r
 		 */
 		if (min_region_size > (1 << 13)) {
 			/* If not a power of 2, make it the next power of 2 */
-			if (min_region_size & (min_region_size - 1))
-				region_size = 1 << fls(region_size);
+			region_size = roundup_pow_of_two(min_region_size);
 			DMINFO("Choosing default region size of %lu sectors",
 			       region_size);
 		} else {