dm: convert ffs to __ffs

ffs counts bit starting with 1 (for the least significant bit), __ffs
counts bits starting with 0. This patch changes various occurrences of ffs
to __ffs and removes subtraction of 1 from the result.

Note that __ffs (unlike ffs) is not defined when called with zero
argument, but it is not called with zero argument in any of these cases.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index f3d608bedffe..74cb7b991d41 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -193,7 +193,7 @@ struct dm_region_hash *dm_region_hash_create(
         rh->max_recovery = max_recovery;
         rh->log = log;
         rh->region_size = region_size;
-        rh->region_shift = ffs(region_size) - 1;
+        rh->region_shift = __ffs(region_size);
         rwlock_init(&rh->hash_lock);
         rh->mask = nr_buckets - 1;
         rh->nr_buckets = nr_buckets;