NFSv4.1: add callback to nfs4_commit_done

Add a callback that the pnfs layout driver can use to do its own
error handling of the data server's COMMIT response.
Signed-off-by: NFred Isaman <iisaman@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -3195,13 +3195,10 @@ static void nfs4_proc_write_setup(struct nfs_write_data *data, struct rpc_messag
 	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_WRITE];
 }
 
-static int nfs4_commit_done(struct rpc_task *task, struct nfs_write_data *data)
+static int nfs4_commit_done_cb(struct rpc_task *task, struct nfs_write_data *data)
 {
 	struct inode *inode = data->inode;
 
-	if (!nfs4_sequence_done(task, &data->res.seq_res))
-		return -EAGAIN;
-
 	if (nfs4_async_handle_error(task, NFS_SERVER(inode), NULL) == -EAGAIN) {
 		nfs_restart_rpc(task, NFS_SERVER(inode)->nfs_client);
 		return -EAGAIN;
@@ -3210,11 +3207,20 @@ static int nfs4_commit_done(struct rpc_task *task, struct nfs_write_data *data)
 	return 0;
 }
 
+static int nfs4_commit_done(struct rpc_task *task, struct nfs_write_data *data)
+{
+	if (!nfs4_sequence_done(task, &data->res.seq_res))
+		return -EAGAIN;
+	return data->write_done_cb(task, data);
+}
+
 static void nfs4_proc_commit_setup(struct nfs_write_data *data, struct rpc_message *msg)
 {
 	struct nfs_server *server = NFS_SERVER(data->inode);
 	
 	data->args.bitmask = server->cache_consistency_bitmask;
+	if (!data->write_done_cb)
+		data->write_done_cb = nfs4_commit_done_cb;
 	data->res.server = server;
 	msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_COMMIT];
 }