[dm-devel] [PATCH] dm verity fec: fix hash block number in verity_fec_decode

[Sunwook Eom]

The error correction data is computed as if data and hash blocks
were concatenated. But hash block number is start from v->hash_start.
So, we have to calculate hash block number based on that.

Fixes: a739ff3f543af ("dm verity: add support for forward error correction")
Signed-off-by: Sunwook Eom <speed.eom at samsung.com>
---
  drivers/md/dm-verity-fec.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 49147e634046..fb41b4f23c48 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -435,7 +435,7 @@ int verity_fec_decode(struct dm_verity *v, struct 
dm_verity_io *io,
      fio->level++;

      if (type == DM_VERITY_BLOCK_TYPE_METADATA)
-        block += v->data_blocks;
+        block = block - v->hash_start + v->data_blocks;

      /*
       * For RS(M, N), the continuous FEC data is divided into blocks of N
-- 
2.17.1