Test for RmChild deadlock.

This provides a test for GitHub PR #378, ie. the previous commit

Change-Id: I9473722e

fs/rmchild_test.go

+// Copyright 2019 the Go-FUSE Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fs
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"testing"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+func TestRmChildParallel(t *testing.T) {
+	want := "hello"
+	root := &Inode{}
+	_, _, clean := testMount(t, root, &Options{
+		FirstAutomaticIno: 1,
+		OnAdd: func(ctx context.Context) {
+			n := root.EmbeddedInode()
+
+			var wg sync.WaitGroup
+			var nms []string
+			for i := 0; i < 100; i++ {
+				nms = append(nms, fmt.Sprint(i))
+			}
+			for _, nm := range nms {
+				wg.Add(1)
+				go func(nm string) {
+					ch := n.NewPersistentInode(
+						ctx,
+						&MemRegularFile{
+							Data: []byte(want),
+							Attr: fuse.Attr{
+								Mode: 0464,
+							},
+						},
+						StableAttr{})
+					n.AddChild(nm, ch, false)
+					wg.Done()
+				}(nm)
+			}
+			for _, nm := range nms {
+				wg.Add(1)
+				go func(nm string) {
+					n.RmChild(nm)
+					wg.Done()
+				}(nm)
+			}
+
+			wg.Wait()
+		},
+	})
+	defer clean()
+}