CRED: Wrap current->cred and a few other accessors

Wrap current->cred and a few other accessors to hide their actual
implementation.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/fs/ioprio.c b/fs/ioprio.c
index bb5210a..5112554 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -123,7 +123,7 @@
 			break;
 		case IOPRIO_WHO_USER:
 			if (!who)
-				user = current->cred->user;
+				user = current_user();
 			else
 				user = find_user(who);
 
@@ -216,7 +216,7 @@
 			break;
 		case IOPRIO_WHO_USER:
 			if (!who)
-				user = current->cred->user;
+				user = current_user();
 			else
 				user = find_user(who);