dm raid: round region_size to power of two

If the user does not supply a bitmap region_size to the dm raid target,
a reasonable size is computed automatically.  If this is not a power of 2,
the md code will report an error later.

This patch catches the problem early and rounds the region_size to the
next power of two.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 45d94a7e7f6d..4a20bf8c72da 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -295,9 +295,11 @@ static int validate_region_size(struct raid_set *rs, unsigned long region_size)
                  * Choose a reasonable default.  All figures in sectors.
                  */
                 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);
                         DMINFO("Choosing default region size of %lu sectors",
                                region_size);
-                        region_size = min_region_size;
                 } else {
                         DMINFO("Choosing default region size of 4MiB");
                         region_size = 1 << 13; /* sectors */