NFS: Avoid referencing the cred twice in async rename/unlink

In both async rename and rename, we take a reference to the
cred in the call arguments.
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/unlink.c

@@ -98,7 +98,7 @@ static void nfs_do_call_unlink(struct inode *inode, struct nfs_unlinkdata *data)
 		.callback_ops = &nfs_unlink_ops,
 		.callback_data = data,
 		.workqueue = nfsiod_workqueue,
-		.flags = RPC_TASK_ASYNC,
+		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 	};
 	struct rpc_task *task;
 	struct inode *dir = d_inode(data->dentry->d_parent);
@@ -341,7 +341,7 @@ nfs_async_rename(struct inode *old_dir, struct inode *new_dir,
 		.callback_ops = &nfs_rename_ops,
 		.workqueue = nfsiod_workqueue,
 		.rpc_client = NFS_CLIENT(old_dir),
-		.flags = RPC_TASK_ASYNC,
+		.flags = RPC_TASK_ASYNC | RPC_TASK_CRED_NOREF,
 	};
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);