CRED: Separate task security context from task_struct

Separate the task security context from task_struct.  At this point, the
security data is temporarily embedded in the task_struct with two pointers
pointing to it.

Note that the Alpha arch is altered as it refers to (E)UID and (E)GID in
entry.S via asm-offsets.

With comment fixes Signed-off-by: Marc Dionne <marc.c.dionne@gmail.com>

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 68d2cd8..bb5210a 100644
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -32,8 +32,8 @@
 	int err;
 	struct io_context *ioc;
 
-	if (task->uid != current_euid() &&
-	    task->uid != current_uid() && !capable(CAP_SYS_NICE))
+	if (task->cred->uid != current_euid() &&
+	    task->cred->uid != current_uid() && !capable(CAP_SYS_NICE))
 		return -EPERM;
 
 	err = security_task_setioprio(task, ioprio);
@@ -123,7 +123,7 @@
 			break;
 		case IOPRIO_WHO_USER:
 			if (!who)
-				user = current->user;
+				user = current->cred->user;
 			else
 				user = find_user(who);
 
@@ -131,7 +131,7 @@
 				break;
 
 			do_each_thread(g, p) {
-				if (p->uid != who)
+				if (p->cred->uid != who)
 					continue;
 				ret = set_task_ioprio(p, ioprio);
 				if (ret)
@@ -216,7 +216,7 @@
 			break;
 		case IOPRIO_WHO_USER:
 			if (!who)
-				user = current->user;
+				user = current->cred->user;
 			else
 				user = find_user(who);
 
@@ -224,7 +224,7 @@
 				break;
 
 			do_each_thread(g, p) {
-				if (p->uid != user->uid)
+				if (p->cred->uid != user->uid)
 					continue;
 				tmpio = get_task_ioprio(p);
 				if (tmpio < 0)