[PATCH v5 07/15] dm-verity: move hash algorithm setup into its own function

[Eric Biggers]

From: Eric Biggers <ebigg...@google.com>

Move the code that sets up the hash transformation into its own
function.  No change in behavior.

Signed-off-by: Eric Biggers <ebigg...@google.com>
---
 drivers/md/dm-verity-target.c | 70 +++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index bb5da66da4c1..88d2a49dca43 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -1224,10 +1224,47 @@ static int verity_parse_opt_args(struct dm_arg_set *as, 
struct dm_verity *v,
        } while (argc && !r);
 
        return r;
 }
 
+static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
+{
+       struct dm_target *ti = v->ti;
+       struct crypto_ahash *ahash;
+
+       v->alg_name = kstrdup(alg_name, GFP_KERNEL);
+       if (!v->alg_name) {
+               ti->error = "Cannot allocate algorithm name";
+               return -ENOMEM;
+       }
+
+       ahash = crypto_alloc_ahash(alg_name, 0,
+                                  v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
+       if (IS_ERR(ahash)) {
+               ti->error = "Cannot initialize hash function";
+               return PTR_ERR(ahash);
+       }
+       v->tfm = ahash;
+
+       /*
+        * dm-verity performance can vary greatly depending on which hash
+        * algorithm implementation is used.  Help people debug performance
+        * problems by logging the ->cra_driver_name.
+        */
+       DMINFO("%s using implementation \"%s\"", alg_name,
+              crypto_hash_alg_common(ahash)->base.cra_driver_name);
+
+       v->digest_size = crypto_ahash_digestsize(ahash);
+       if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
+               ti->error = "Digest size too big";
+               return -EINVAL;
+       }
+       v->ahash_reqsize = sizeof(struct ahash_request) +
+                          crypto_ahash_reqsize(ahash);
+       return 0;
+}
+
 /*
  * Target parameters:
  *     <version>       The current format is version 1.
  *                     Vsn 0 is compatible with original Chromium OS releases.
  *     <data device>
@@ -1348,42 +1385,13 @@ static int verity_ctr(struct dm_target *ti, unsigned 
int argc, char **argv)
                r = -EINVAL;
                goto bad;
        }
        v->hash_start = num_ll;
 
-       v->alg_name = kstrdup(argv[7], GFP_KERNEL);
-       if (!v->alg_name) {
-               ti->error = "Cannot allocate algorithm name";
-               r = -ENOMEM;
-               goto bad;
-       }
-
-       v->tfm = crypto_alloc_ahash(v->alg_name, 0,
-                                   v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
-       if (IS_ERR(v->tfm)) {
-               ti->error = "Cannot initialize hash function";
-               r = PTR_ERR(v->tfm);
-               v->tfm = NULL;
-               goto bad;
-       }
-
-       /*
-        * dm-verity performance can vary greatly depending on which hash
-        * algorithm implementation is used.  Help people debug performance
-        * problems by logging the ->cra_driver_name.
-        */
-       DMINFO("%s using implementation \"%s\"", v->alg_name,
-              crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
-
-       v->digest_size = crypto_ahash_digestsize(v->tfm);
-       if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
-               ti->error = "Digest size too big";
-               r = -EINVAL;
+       r = verity_setup_hash_alg(v, argv[7]);
+       if (r)
                goto bad;
-       }
-       v->ahash_reqsize = sizeof(struct ahash_request) +
-               crypto_ahash_reqsize(v->tfm);
 
        v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
        if (!v->root_digest) {
                ti->error = "Cannot allocate root digest";
                r = -ENOMEM;
-- 
2.45.1