dm integrity: use hex2bin instead of open-coded variant

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

drivers/md/dm-integrity.c

@@ -2496,8 +2496,6 @@ static int get_alg_and_key(const char *arg, struct alg_spec *a, char **error, ch
 
 	k = strchr(a->alg_string, ':');
 	if (k) {
-		unsigned i;
-
 		*k = 0;
 		a->key_string = k + 1;
 		if (strlen(a->key_string) & 1)
@@ -2507,16 +2505,8 @@ static int get_alg_and_key(const char *arg, struct alg_spec *a, char **error, ch
 		a->key = kmalloc(a->key_size, GFP_KERNEL);
 		if (!a->key)
 			goto nomem;
-		for (i = 0; i < a->key_size; i++) {
-			char digit[3];
-			digit[0] = a->key_string[i * 2];
-			digit[1] = a->key_string[i * 2 + 1];
-			digit[2] = 0;
-			if (strspn(digit, "0123456789abcdefABCDEF") != 2)
-				goto inval;
-			if (kstrtou8(digit, 16, &a->key[i]))
-				goto inval;
-		}
+		if (hex2bin(a->key, a->key_string, a->key_size))
+			goto inval;
 	}
 
 	return 0;