fs: add a test verifying that forget drops nodes

Change-Id: Ife141f38f2b7598223935963e2916b0b9a609cca

fs/forget_test.go

+// Copyright 2020 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"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/user"
+	"path/filepath"
+	"syscall"
+	"testing"
+	"time"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+	"github.com/hanwen/go-fuse/v2/internal/testutil"
+)
+
+type allChildrenNode struct {
+	Inode
+
+	depth int
+}
+
+var _ = (NodeLookuper)((*allChildrenNode)(nil))
+var _ = (NodeReaddirer)((*allChildrenNode)(nil))
+
+func (n *allChildrenNode) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (*Inode, syscall.Errno) {
+	if n.depth == 0 {
+		return nil, syscall.ENOENT
+	}
+	stable := StableAttr{
+		Mode: syscall.S_IFDIR,
+	}
+
+	if n.depth == 1 {
+		stable.Mode = syscall.S_IFREG
+	}
+	childFN := &allChildrenNode{
+		depth: n.depth - 1,
+	}
+	child := n.NewInode(ctx, childFN, stable)
+	return child, 0
+}
+
+func (n *allChildrenNode) Readdir(ctx context.Context) (DirStream, syscall.Errno) {
+	var list []fuse.DirEntry
+	var m uint32 = syscall.S_IFDIR
+	if n.depth == 1 {
+		m = syscall.S_IFREG
+	}
+	for i := 0; i < 100; i++ {
+		list = append(list, fuse.DirEntry{
+			Name: fmt.Sprintf("%d", i),
+			Mode: m,
+		})
+	}
+	return NewListDirStream(list), 0
+}
+
+func TestForget(t *testing.T) {
+	u, err := user.Current()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if u.Uid != "0" {
+		t.Skip("must run test as root")
+	}
+	root := &allChildrenNode{
+		depth: 2,
+	}
+	sec := time.Second
+	options := &Options{
+		FirstAutomaticIno: 1,
+		EntryTimeout:      &sec,
+	}
+	options.Debug = testutil.VerboseTest()
+	dir, err := ioutil.TempDir("", "TestForget")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rawFS := NewNodeFS(root, options)
+	server, err := fuse.NewServer(rawFS, dir, &options.MountOptions)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	go server.Serve()
+	if err := server.WaitMount(); err != nil {
+		t.Fatal(err)
+	}
+
+	nop := func(path string, info os.FileInfo, err error) error {
+		return nil
+	}
+
+	if err := filepath.Walk(dir, nop); err != nil {
+		t.Fatal(err)
+	}
+
+	log.Println("dropping cache")
+	if err := ioutil.WriteFile("/proc/sys/vm/drop_caches", []byte("2"), 0644); err != nil {
+
+	}
+	time.Sleep(time.Second)
+
+	bridge := rawFS.(*rawBridge)
+	bridge.mu.Lock()
+	l := len(bridge.nodes)
+	bridge.mu.Unlock()
+	if l != 1 {
+		t.Fatalf("got %d live nodes, want 1", l)
+	}
+}