NFSv4: Convert nfs41_free_stateid to use an asynchronous RPC call

The main reason for doing this is will be to allow for an asynchronous
RPC mode that we can use for freeing lock stateids as per section
8.2.4 of RFC5661.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -6783,26 +6783,76 @@ static int nfs41_test_stateid(struct nfs_server *server, nfs4_stateid *stateid)
 	return err;
 }
 
-static int _nfs4_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
-{
-	struct nfs41_free_stateid_args args = {
-		.stateid = stateid,
-	};
+struct nfs_free_stateid_data {
+	struct nfs_server *server;
+	struct nfs41_free_stateid_args args;
 	struct nfs41_free_stateid_res res;
+};
+
+static void nfs41_free_stateid_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs_free_stateid_data *data = calldata;
+	nfs41_setup_sequence(nfs4_get_session(data->server),
+			&data->args.seq_args,
+			&data->res.seq_res,
+			task);
+}
+
+static void nfs41_free_stateid_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs_free_stateid_data *data = calldata;
+
+	nfs41_sequence_done(task, &data->res.seq_res);
+
+	switch (task->tk_status) {
+	case -NFS4ERR_DELAY:
+		if (nfs4_async_handle_error(task, data->server, NULL) == -EAGAIN)
+			rpc_restart_call_prepare(task);
+	}
+}
+
+static void nfs41_free_stateid_release(void *calldata)
+{
+	kfree(calldata);
+}
+
+const struct rpc_call_ops nfs41_free_stateid_ops = {
+	.rpc_call_prepare = nfs41_free_stateid_prepare,
+	.rpc_call_done = nfs41_free_stateid_done,
+	.rpc_release = nfs41_free_stateid_release,
+};
+
+static struct rpc_task *_nfs41_free_stateid(struct nfs_server *server,
+		nfs4_stateid *stateid,
+		bool privileged)
+{
 	struct rpc_message msg = {
 		.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_FREE_STATEID],
-		.rpc_argp = &args,
-		.rpc_resp = &res,
 	};
-	int status;
+	struct rpc_task_setup task_setup = {
+		.rpc_client = server->client,
+		.rpc_message = &msg,
+		.callback_ops = &nfs41_free_stateid_ops,
+		.flags = RPC_TASK_ASYNC,
+	};
+	struct nfs_free_stateid_data *data;
 
 	dprintk("NFS call  free_stateid %p\n", stateid);
-	nfs41_init_sequence(&args.seq_args, &res.seq_res, 0);
-	nfs4_set_sequence_privileged(&args.seq_args);
-	status = nfs4_call_sync_sequence(server->client, server, &msg,
-			&args.seq_args, &res.seq_res);
-	dprintk("NFS reply free_stateid: %d\n", status);
-	return status;
+	data = kmalloc(sizeof(*data), GFP_NOFS);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+	data->server = server;
+	nfs4_stateid_copy(&data->args.stateid, stateid);
+
+	task_setup.callback_data = data;
+
+	msg.rpc_argp = &data->args;
+	msg.rpc_resp = &data->res;
+	nfs41_init_sequence(&data->args.seq_args, &data->res.seq_res, 0);
+	if (privileged)
+		nfs4_set_sequence_privileged(&data->args.seq_args);
+
+	return rpc_run_task(&task_setup);
 }
 
 /**
@@ -6816,15 +6866,17 @@ static int _nfs4_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
  */
 static int nfs41_free_stateid(struct nfs_server *server, nfs4_stateid *stateid)
 {
-	struct nfs4_exception exception = { };
-	int err;
-	do {
-		err = _nfs4_free_stateid(server, stateid);
-		if (err != -NFS4ERR_DELAY)
-			break;
-		nfs4_handle_exception(server, err, &exception);
-	} while (exception.retry);
-	return err;
+	struct rpc_task *task;
+	int ret;
+
+	task = _nfs41_free_stateid(server, stateid, true);
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+	ret = rpc_wait_for_completion_task(task);
+	if (!ret)
+		ret = task->tk_status;
+	rpc_put_task(task);
+	return ret;
 }
 
 static bool nfs41_match_stateid(const nfs4_stateid *s1,

fs/nfs/nfs4xdr.c

@@ -2003,7 +2003,7 @@ static void encode_free_stateid(struct xdr_stream *xdr,
 				struct compound_hdr *hdr)
 {
 	encode_op_hdr(xdr, OP_FREE_STATEID, decode_free_stateid_maxsz, hdr);
-	encode_nfs4_stateid(xdr, args->stateid);
+	encode_nfs4_stateid(xdr, &args->stateid);
 }
 #endif /* CONFIG_NFS_V4_1 */
 

include/linux/nfs_xdr.h

@@ -1176,7 +1176,7 @@ struct nfs41_test_stateid_res {
 
 struct nfs41_free_stateid_args {
 	struct nfs4_sequence_args	seq_args;
-	nfs4_stateid			*stateid;
+	nfs4_stateid			stateid;
 };
 
 struct nfs41_free_stateid_res {