nfs: convert nfs_rename to use async_rename infrastructure

There isn't much sense in maintaining two separate versions of rename
code. Convert nfs_rename to use the asynchronous rename infrastructure
that nfs_sillyrename uses, and emulate synchronous behavior by having
the task just wait on the reply.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Anna Schumaker <Anna.Schumaker@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/dir.c

@@ -1940,6 +1940,7 @@ int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	struct inode *old_inode = old_dentry->d_inode;
 	struct inode *new_inode = new_dentry->d_inode;
 	struct dentry *dentry = NULL, *rehash = NULL;
+	struct rpc_task *task;
 	int error = -EBUSY;
 
 	dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
@@ -1987,8 +1988,16 @@ int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	if (new_inode != NULL)
 		NFS_PROTO(new_inode)->return_delegation(new_inode);
 
-	error = NFS_PROTO(old_dir)->rename(old_dir, &old_dentry->d_name,
-					   new_dir, &new_dentry->d_name);
+	task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
+	if (IS_ERR(task)) {
+		error = PTR_ERR(task);
+		goto out;
+	}
+
+	error = rpc_wait_for_completion_task(task);
+	if (error == 0)
+		error = task->tk_status;
+	rpc_put_task(task);
 	nfs_mark_for_revalidate(old_inode);
 out:
 	if (rehash)