NFSv4.1: Fix layoutcommit error handling

Firstly, task->tk_status will always return negative error values,
so the current tests for 'NFS4ERR_DELEG_REVOKED' etc. are all being
ignored.
Secondly, clean up the code so that we only need to test
task->tk_status once!

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: stable@vger.kernel.org

fs/nfs/nfs4proc.c

@@ -6112,21 +6112,22 @@ nfs4_layoutcommit_done(struct rpc_task *task, void *calldata)
 		return;
 
 	switch (task->tk_status) { /* Just ignore these failures */
-	case NFS4ERR_DELEG_REVOKED: /* layout was recalled */
-	case NFS4ERR_BADIOMODE:     /* no IOMODE_RW layout for range */
-	case NFS4ERR_BADLAYOUT:     /* no layout */
-	case NFS4ERR_GRACE:	    /* loca_recalim always false */
+	case -NFS4ERR_DELEG_REVOKED: /* layout was recalled */
+	case -NFS4ERR_BADIOMODE:     /* no IOMODE_RW layout for range */
+	case -NFS4ERR_BADLAYOUT:     /* no layout */
+	case -NFS4ERR_GRACE:	    /* loca_recalim always false */
 		task->tk_status = 0;
-	}
-
-	if (nfs4_async_handle_error(task, server, NULL) == -EAGAIN) {
-		rpc_restart_call_prepare(task);
-		return;
-	}
-
-	if (task->tk_status == 0)
+		break;
+	case 0:
 		nfs_post_op_update_inode_force_wcc(data->args.inode,
 						   data->res.fattr);
+		break;
+	default:
+		if (nfs4_async_handle_error(task, server, NULL) == -EAGAIN) {
+			rpc_restart_call_prepare(task);
+			return;
+		}
+	}
 }
 
 static void nfs4_layoutcommit_release(void *calldata)