fscrypt: clarify what is meant by a per-file key

Now that there's sometimes a second type of per-file key (the dirhash
key), clarify some function names, macros, and documentation that
specifically deal with per-file *encryption* keys.

Link: https://lore.kernel.org/r/20200120223201.241390-4-ebiggers@kernel.org
Reviewed-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
diff --git a/fs/crypto/keysetup_v1.c b/fs/crypto/keysetup_v1.c
index 3578c1c..801b48c 100644
--- a/fs/crypto/keysetup_v1.c
+++ b/fs/crypto/keysetup_v1.c
@@ -9,7 +9,7 @@
  * This file implements compatibility functions for the original encryption
  * policy version ("v1"), including:
  *
- * - Deriving per-file keys using the AES-128-ECB based KDF
+ * - Deriving per-file encryption keys using the AES-128-ECB based KDF
  *   (rather than the new method of using HKDF-SHA512)
  *
  * - Retrieving fscrypt master keys from process-subscribed keyrings
@@ -283,7 +283,7 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci,
 	if (err)
 		goto out;
 
-	err = fscrypt_set_derived_key(ci, derived_key);
+	err = fscrypt_set_per_file_enc_key(ci, derived_key);
 out:
 	kzfree(derived_key);
 	return err;