fscrypt: move fscrypt_valid_enc_modes() to policy.c

fscrypt_valid_enc_modes() is only used by policy.c, so move it to there.

Also adjust the order of the checks to be more natural, matching the
numerical order of the constants and also keeping AES-256 (the
recommended default) first in the list.

No change in behavior.

Link: https://lore.kernel.org/r/20191209211829.239800-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

fs/crypto/fscrypt_private.h

@@ -206,24 +206,6 @@ typedef enum {
 	FS_ENCRYPT,
 } fscrypt_direction_t;
 
-static inline bool fscrypt_valid_enc_modes(u32 contents_mode,
-					   u32 filenames_mode)
-{
-	if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
-	    filenames_mode == FSCRYPT_MODE_AES_128_CTS)
-		return true;
-
-	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
-	    filenames_mode == FSCRYPT_MODE_AES_256_CTS)
-		return true;
-
-	if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
-	    filenames_mode == FSCRYPT_MODE_ADIANTUM)
-		return true;
-
-	return false;
-}
-
 /* crypto.c */
 extern struct kmem_cache *fscrypt_info_cachep;
 extern int fscrypt_initialize(unsigned int cop_flags);

fs/crypto/policy.c

@@ -29,6 +29,23 @@ bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
 	return !memcmp(policy1, policy2, fscrypt_policy_size(policy1));
 }
 
+static bool fscrypt_valid_enc_modes(u32 contents_mode, u32 filenames_mode)
+{
+	if (contents_mode == FSCRYPT_MODE_AES_256_XTS &&
+	    filenames_mode == FSCRYPT_MODE_AES_256_CTS)
+		return true;
+
+	if (contents_mode == FSCRYPT_MODE_AES_128_CBC &&
+	    filenames_mode == FSCRYPT_MODE_AES_128_CTS)
+		return true;
+
+	if (contents_mode == FSCRYPT_MODE_ADIANTUM &&
+	    filenames_mode == FSCRYPT_MODE_ADIANTUM)
+		return true;
+
+	return false;
+}
+
 static bool supported_direct_key_modes(const struct inode *inode,
 				       u32 contents_mode, u32 filenames_mode)
 {