[dm-devel] [PATCH] dm-raid: fix bug when round up region_size

[heinzm at redhat.com]

From: Heinz Mauelshagen <heinzm at redhat.com>

Liong,
thanks for the catch.
Introduced minor modification utilizing the is_power_of_2() inline.

---

If region_size is not supplied by userspace and the device is very
large, there is a bug in current code preventing region_size from being
correctly set.


Signed-off-by: Lidong Zhong <lzhong at suse.com>
Acked-by:      Heinz Mauelshagen <heinzm at redhat.com>
Tested-by:     Heinz Mauelshagen <heinzm at redhat.com>

---
 drivers/md/dm-raid.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 4880b69..264aef4 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -325,8 +325,10 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
 		 */
 		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);
+			if (is_power_of_2(min_region_size))
+				region_size = min_region_size;
+			else
+				region_size = 1 << fls(min_region_size);
 			DMINFO("Choosing default region size of %lu sectors",
 			       region_size);
 		} else {
-- 
1.9.3