NFSv4: Don't free slots prematurely if requesting a directory delegation

When requesting a directory delegation, it is imperative to hold the
slot until the delegation state has been recorded. Otherwise, if a
recall comes in, the call to referring_call_exists() will assume the
processing is done, and when it doesn't find a delegation, it will
assume it has been returned.

Fixes: 156b094 ("NFS: Request a directory delegation on ACCESS, CREATE, and UNLINK")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

Author: Trond Myklebust

fs/nfs/nfs4proc.c

@@ -4494,6 +4494,25 @@ static bool should_request_dir_deleg(struct inode *inode)
 }
 #endif /* CONFIG_NFS_V4_1 */
 
+static void nfs4_call_getattr_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs4_call_sync_data *data = calldata;
+	nfs4_setup_sequence(data->seq_server->nfs_client, data->seq_args,
+			    data->seq_res, task);
+}
+
+static void nfs4_call_getattr_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs4_call_sync_data *data = calldata;
+
+	nfs4_sequence_process(task, data->seq_res);
+}
+
+static const struct rpc_call_ops nfs4_call_getattr_ops = {
+	.rpc_call_prepare = nfs4_call_getattr_prepare,
+	.rpc_call_done = nfs4_call_getattr_done,
+};
+
 static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
 				struct nfs_fattr *fattr, struct inode *inode)
 {
@@ -4511,16 +4530,26 @@ static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
 		.rpc_argp = &args,
 		.rpc_resp = &res,
 	};
+	struct nfs4_call_sync_data data = {
+		.seq_server = server,
+		.seq_args = &args.seq_args,
+		.seq_res = &res.seq_res,
+	};
+	struct rpc_task_setup task_setup = {
+		.rpc_client = server->client,
+		.rpc_message = &msg,
+		.callback_ops = &nfs4_call_getattr_ops,
+		.callback_data = &data,
+	};
 	struct nfs4_gdd_res gdd_res;
-	unsigned short task_flags = 0;
 	int status;
 
 	if (nfs4_has_session(server->nfs_client))
-		task_flags = RPC_TASK_MOVEABLE;
+		task_setup.flags = RPC_TASK_MOVEABLE;
 
 	/* Is this is an attribute revalidation, subject to softreval? */
 	if (inode && (server->flags & NFS_MOUNT_SOFTREVAL))
-		task_flags |= RPC_TASK_TIMEOUT;
+		task_setup.flags |= RPC_TASK_TIMEOUT;
 
 	args.get_dir_deleg = should_request_dir_deleg(inode);
 	if (args.get_dir_deleg)
@@ -4530,22 +4559,24 @@ static int _nfs4_proc_getattr(struct nfs_server *server, struct nfs_fh *fhandle,
 	nfs_fattr_init(fattr);
 	nfs4_init_sequence(&args.seq_args, &res.seq_res, 0, 0);
 
-	status = nfs4_do_call_sync(server->client, server, &msg,
-				   &args.seq_args, &res.seq_res, task_flags);
+	status = nfs4_call_sync_custom(&task_setup);
+
 	if (args.get_dir_deleg) {
 		switch (status) {
 		case 0:
 			if (gdd_res.status != GDD4_OK)
 				break;
-			status = nfs_inode_set_delegation(
-				inode, current_cred(), FMODE_READ,
-				&gdd_res.deleg, 0, NFS4_OPEN_DELEGATE_READ);
+			nfs_inode_set_delegation(inode, current_cred(),
+						 FMODE_READ, &gdd_res.deleg, 0,
+						 NFS4_OPEN_DELEGATE_READ);
 			break;
 		case -ENOTSUPP:
 		case -EOPNOTSUPP:
 			server->caps &= ~NFS_CAP_DIR_DELEG;
 		}
 	}
+
+	nfs4_sequence_free_slot(&res.seq_res);
 	return status;
 }