[PATCH v6 07/15] dm-verity: move hash algorithm setup into its own function

[Eric Biggers <ebiggers@xxxxxxxxxx>]

From: Eric Biggers <ebiggers@xxxxxxxxxx>

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

Reviewed-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
 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;
-- 
2.45.2