dm verity fec: fix block calculation
do_div was replaced with div64_u64 at some point, causing a bug with
block calculation due to incompatible semantics of the two functions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Fixes: a739ff3f543a ("dm verity: add support for forward error correction")
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 459a9f8..0f0eb8a 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -453,9 +453,7 @@
*/
offset = block << v->data_dev_block_bits;
-
- res = offset;
- div64_u64(res, v->fec->rounds << v->data_dev_block_bits);
+ res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits);
/*
* The base RS block we can feed to the interleaver to find out all