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/ipc/mqueue.c b/ipc/mqueue.c
index e1885b4..1151881 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -112,6 +112,7 @@
 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
 							struct mq_attr *attr)
 {
+	struct user_struct *u = current_user();
 	struct inode *inode;
 
 	inode = new_inode(sb);
@@ -126,7 +127,6 @@
 		if (S_ISREG(mode)) {
 			struct mqueue_inode_info *info;
 			struct task_struct *p = current;
-			struct user_struct *u = p->cred->user;
 			unsigned long mq_bytes, mq_msg_tblsz;
 
 			inode->i_fop = &mqueue_file_operations;