MemUnionFs: centralize locking, implement Reap/Clear.

unionfs/memunionfs.go

@@ -19,7 +19,7 @@ type MemUnionFs struct {
 	backingStore string
 	root         *memNode
 
-	mutex    sync.Mutex
+	mutex    sync.RWMutex
 	nextFree int
 
 	readonly fuse.FileSystem
@@ -29,20 +29,39 @@ type memNode struct {
 	fuse.DefaultFsNode
 	fs *MemUnionFs
 
-	original string
-
 	// protects mutable data below.
-	mutex   sync.RWMutex
+	mutex    *sync.RWMutex
 	backing  string
+	original string
 	changed  bool
 	link     string
 	info     os.FileInfo
 	deleted  map[string]bool
 }
 
-func (me *MemUnionFs) getFilename() string {
+type Result struct {
+	Info     *os.FileInfo
+	Original string
+	Backing  string
+	Link     string
+}
+
+func (me *MemUnionFs) Reap() map[string]*Result {
+	me.mutex.RLock()
+	defer me.mutex.RUnlock()
+
+	m := map[string]*Result{}
+	me.root.Reap("", m)
+	return m
+}
+
+func (me *MemUnionFs) Clear() {
 	me.mutex.Lock()
 	defer me.mutex.Unlock()
+	me.root.Clear("")
+}
+
+func (me *MemUnionFs) getFilename() string {
 	id := me.nextFree
 	me.nextFree++
 	return fmt.Sprintf("%s/%d", me.backingStore, id)
@@ -60,6 +79,7 @@ func (me *MemUnionFs) StatFs() *fuse.StatfsOut {
 func (me *MemUnionFs) newNode(isdir bool) *memNode {
 	n := &memNode{
 		fs:    me,
+		mutex: &me.mutex,
 	}
 	if isdir {
 		n.deleted = map[string]bool{}
@@ -171,6 +191,7 @@ func (me *memNode) Symlink(name string, content string, context *fuse.Context) (
 	n := me.newNode(false)
 	n.info.Mode = fuse.S_IFLNK | 0777
 	n.link = content
+	n.changed = true
 	me.Inode().AddChild(name, n.Inode())
 	me.touch()
 	me.deleted[name] = false, false
@@ -190,10 +211,11 @@ func (me *memNode) Rename(oldName string, newParent fuse.FsNode, newName string,
 }
 
 func (me *memNode) Link(name string, existing fuse.FsNode, context *fuse.Context) (fi *os.FileInfo, newNode fuse.FsNode, code fuse.Status) {
-	me.mutex.Lock()
-	defer me.mutex.Unlock()
 	me.Inode().AddChild(name, existing.Inode())
 	fi, code = existing.GetAttr(nil, context)
+
+	me.mutex.Lock()
+	defer me.mutex.Unlock()
 	me.touch()
 	me.deleted[name] = false, false
 	return fi, existing, code
@@ -202,6 +224,7 @@ func (me *memNode) Link(name string, existing fuse.FsNode, context *fuse.Context
 func (me *memNode) Create(name string, flags uint32, mode uint32, context *fuse.Context) (file fuse.File, fi *os.FileInfo, newNode fuse.FsNode, code fuse.Status) {
 	me.mutex.Lock()
 	defer me.mutex.Unlock()
+
 	n := me.newNode(false)
 	n.info.Mode = mode | fuse.S_IFREG
 	n.changed = true
@@ -229,9 +252,10 @@ func (me *memNodeFile) InnerFile() fuse.File {
 func (me *memNodeFile) Flush() fuse.Status {
 	code := me.File.Flush()
 	if me.writable {
+		fi, _ := me.File.GetAttr()
+
 		me.node.mutex.Lock()
 		defer me.node.mutex.Unlock()
-		fi, _ := me.File.GetAttr()
 		me.node.info.Size = fi.Size
 		me.node.info.Blocks = fi.Blocks
 	}
@@ -253,7 +277,7 @@ func (me *memNode) promote() {
 		destfs := &fuse.LoopbackFileSystem{Root: "/"}
 		fuse.CopyFile(me.fs.readonly, destfs,
 			me.original, strings.TrimLeft(me.backing, "/"), nil)
-
+		me.original = ""
 		files := me.Inode().Files(0)
 		for _, f := range files {
 			mf := f.File.(*memNodeFile)
@@ -272,12 +296,14 @@ func (me *memNode) promote() {
 func (me *memNode) Open(flags uint32, context *fuse.Context) (file fuse.File, code fuse.Status) {
 	if flags&fuse.O_ANYWRITE != 0 {
 		me.mutex.Lock()
-		defer me.mutex.Unlock()
-
 		me.promote()
 		me.touch()
+		me.mutex.Unlock()
 	}
 
+	me.mutex.RLock()
+	defer me.mutex.RUnlock()
+
 	if me.backing != "" {
 		f, err := os.OpenFile(me.backing, int(flags), 0666)
 		if err != nil {
@@ -383,3 +409,37 @@ func (me *memNode) OpenDir(context *fuse.Context) (stream chan fuse.DirEntry, co
 	close(stream)
 	return stream, fuse.OK
 }
+
+func (me *memNode) Reap(path string, results map[string]*Result) {
+	for name, _ := range me.deleted {
+		p := filepath.Join(path, name)
+		results[p] = &Result{}
+	}
+
+	if me.changed {
+		info := me.info
+		results[path] = &Result{
+			Info:     &info,
+			Link:     me.link,
+			Backing:  me.backing,
+			Original: me.original,
+		}
+	}
+
+	for n, ch := range me.Inode().FsChildren() {
+		p := filepath.Join(path, n)
+		ch.FsNode().(*memNode).Reap(p, results)
+	}
+}
+
+func (me *memNode) Clear(path string) {
+	me.original = path
+	me.changed = false
+	me.backing = ""
+	me.deleted = make(map[string]bool)
+	for n, ch := range me.Inode().FsChildren() {
+		p := filepath.Join(path, n)
+		mn := ch.FsNode().(*memNode)
+		mn.Clear(p)
+	}
+}

unionfs/memunionfs_test.go

@@ -18,7 +18,7 @@ var _ = log.Print
 
 var CheckSuccess = fuse.CheckSuccess
 
-func setupMemUfs(t *testing.T) (workdir string, cleanup func()) {
+func setupMemUfs(t *testing.T) (workdir string, ufs *MemUnionFs, cleanup func()) {
 	// Make sure system setting does not affect test.
 	syscall.Umask(0)
 
@@ -49,14 +49,14 @@ func setupMemUfs(t *testing.T) (workdir string, cleanup func()) {
 	state.Debug = fuse.VerboseTest()
 	go state.Loop()
 
-	return wd, func() {
+	return wd, memFs, func() {
 		state.Unmount()
 		os.RemoveAll(wd)
 	}
 }
 
 func TestMemUnionFsSymlink(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.Symlink("/foobar", wd+"/mount/link")
@@ -68,10 +68,15 @@ func TestMemUnionFsSymlink(t *testing.T) {
 	if val != "/foobar" {
 		t.Errorf("symlink mismatch: %v", val)
 	}
+
+	r := ufs.Reap()
+	if len(r) != 2 || r["link"] == nil || r["link"].Link != "/foobar" {
+		t.Errorf("expect 1 symlink reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsSymlinkPromote(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.Mkdir(wd+"/ro/subdir", 0755)
@@ -79,10 +84,15 @@ func TestMemUnionFsSymlinkPromote(t *testing.T) {
 
 	err = os.Symlink("/foobar", wd+"/mount/subdir/link")
 	CheckSuccess(err)
+		
+	r := ufs.Reap()
+	if len(r) != 2 || r["subdir"] == nil || r["subdir/link"] == nil || r["subdir/link"].Link != "/foobar" {
+		t.Errorf("expect 1 symlink reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsChtimes(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	writeToFile(wd+"/ro/file", "a")
@@ -96,10 +106,15 @@ func TestMemUnionFsChtimes(t *testing.T) {
 	if fi.Atime_ns != 82e9 || fi.Mtime_ns != 83e9 {
 		t.Error("Incorrect timestamp", fi)
 	}
+
+	r := ufs.Reap()
+	if r["file"] == nil || r["file"].Original == "" {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsChmod(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	ro_fn := wd + "/ro/file"
@@ -113,10 +128,15 @@ func TestMemUnionFsChmod(t *testing.T) {
 	if fi.Mode&07777 != 07070 {
 		t.Errorf("Unexpected mode found: %o", fi.Mode)
 	}
+
+	r := ufs.Reap()
+	if r["file"] == nil || r["file"].Original == "" {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsChown(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	ro_fn := wd + "/ro/file"
@@ -131,7 +151,7 @@ func TestMemUnionFsChown(t *testing.T) {
 }
 
 func TestMemUnionFsDelete(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	writeToFile(wd+"/ro/file", "a")
@@ -145,10 +165,15 @@ func TestMemUnionFsDelete(t *testing.T) {
 	if err == nil {
 		t.Fatal("should have disappeared.")
 	}
+
+	r := ufs.Reap()
+	if r["file"] == nil || r["file"].Info != nil {
+		t.Errorf("expect 1 deletion reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsBasic(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	writeToFile(wd+"/mount/rw", "a")
@@ -184,17 +209,22 @@ func TestMemUnionFsBasic(t *testing.T) {
 }
 
 func TestMemUnionFsPromote(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.Mkdir(wd+"/ro/subdir", 0755)
 	CheckSuccess(err)
 	writeToFile(wd+"/ro/subdir/file", "content")
 	writeToFile(wd+"/mount/subdir/file", "other-content")
+
+	r := ufs.Reap()
+	if r["subdir/file"] == nil || r["subdir/file"].Backing == "" {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsCreate(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.MkdirAll(wd+"/ro/subdir/sub2", 0755)
@@ -202,10 +232,15 @@ func TestMemUnionFsCreate(t *testing.T) {
 	writeToFile(wd+"/mount/subdir/sub2/file", "other-content")
 	_, err = os.Lstat(wd + "/mount/subdir/sub2/file")
 	CheckSuccess(err)
+	
+	r := ufs.Reap()
+	if r["subdir/sub2/file"] == nil || r["subdir/sub2/file"].Backing == "" {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsOpenUndeletes(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	writeToFile(wd+"/ro/file", "X")
@@ -213,11 +248,10 @@ func TestMemUnionFsOpenUndeletes(t *testing.T) {
 	CheckSuccess(err)
 	writeToFile(wd+"/mount/file", "X")
 	_, err = os.Lstat(wd + "/mount/file")
-	CheckSuccess(err)
 }
 
 func TestMemUnionFsMkdir(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	dirname := wd + "/mount/subdir"
@@ -226,10 +260,15 @@ func TestMemUnionFsMkdir(t *testing.T) {
 
 	err = os.Remove(dirname)
 	CheckSuccess(err)
+
+	r := ufs.Reap()
+	if len(r) > 2 || r[""] == nil || r["subdir"] == nil {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsMkdirPromote(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, ufs, clean := setupMemUfs(t)
 	defer clean()
 
 	dirname := wd + "/ro/subdir/subdir2"
@@ -238,10 +277,15 @@ func TestMemUnionFsMkdirPromote(t *testing.T) {
 
 	err = os.Mkdir(wd+"/mount/subdir/subdir2/dir3", 0755)
 	CheckSuccess(err)
+
+	r := ufs.Reap()
+	if r["subdir/subdir2/dir3"] == nil ||  r["subdir/subdir2/dir3"].Info.Mode & fuse.S_IFDIR == 0 {
+		t.Errorf("expect 1 file reap result: %v", r)
+	}
 }
 
 func TestMemUnionFsRmdirMkdir(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.Mkdir(wd+"/ro/subdir", 0755)
@@ -256,7 +300,7 @@ func TestMemUnionFsRmdirMkdir(t *testing.T) {
 }
 
 func TestMemUnionFsLink(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	content := "blabla"
@@ -282,7 +326,7 @@ func TestMemUnionFsLink(t *testing.T) {
 }
 
 func TestMemUnionFsTruncate(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	writeToFile(wd+"/ro/file", "hello")
@@ -295,7 +339,7 @@ func TestMemUnionFsTruncate(t *testing.T) {
 
 func TestMemUnionFsCopyChmod(t *testing.T) {
 	t.Log("TestCopyChmod")
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	contents := "hello"
@@ -321,7 +365,7 @@ func TestMemUnionFsCopyChmod(t *testing.T) {
 
 func TestMemUnionFsTruncateTimestamp(t *testing.T) {
 	t.Log("TestTruncateTimestamp")
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	contents := "hello"
@@ -344,7 +388,7 @@ func TestMemUnionFsTruncateTimestamp(t *testing.T) {
 
 func TestMemUnionFsRemoveAll(t *testing.T) {
 	t.Log("TestRemoveAll")
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.MkdirAll(wd+"/ro/dir/subdir", 0755)
@@ -368,7 +412,7 @@ func TestMemUnionFsRemoveAll(t *testing.T) {
 }
 
 func TestMemUnionFsRmRf(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	err := os.MkdirAll(wd+"/ro/dir/subdir", 0755)
@@ -394,7 +438,7 @@ func TestMemUnionFsRmRf(t *testing.T) {
 }
 
 func TestMemUnionFsDeletedGetAttr(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	err := ioutil.WriteFile(wd+"/ro/file", []byte("blabla"), 0644)
@@ -413,7 +457,7 @@ func TestMemUnionFsDeletedGetAttr(t *testing.T) {
 }
 
 func TestMemUnionFsDoubleOpen(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 	err := ioutil.WriteFile(wd+"/ro/file", []byte("blablabla"), 0644)
 	CheckSuccess(err)
@@ -451,7 +495,7 @@ func TestMemUnionFsFdLeak(t *testing.T) {
 	beforeEntries, err := ioutil.ReadDir("/proc/self/fd")
 	CheckSuccess(err)
 
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	err = ioutil.WriteFile(wd+"/ro/file", []byte("blablabla"), 0644)
 	CheckSuccess(err)
 
@@ -472,7 +516,7 @@ func TestMemUnionFsFdLeak(t *testing.T) {
 }
 
 func TestMemUnionFsStatFs(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	s1 := syscall.Statfs_t{}
@@ -486,7 +530,7 @@ func TestMemUnionFsStatFs(t *testing.T) {
 }
 
 func TestMemUnionFsFlushSize(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	fn := wd + "/mount/file"
@@ -507,7 +551,7 @@ func TestMemUnionFsFlushSize(t *testing.T) {
 }
 
 func TestMemUnionFsFlushRename(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	err := ioutil.WriteFile(wd+"/mount/file", []byte("x"), 0644)
@@ -534,7 +578,7 @@ func TestMemUnionFsFlushRename(t *testing.T) {
 }
 
 func TestMemUnionFsTruncGetAttr(t *testing.T) {
-	wd, clean := setupMemUfs(t)
+	wd, _, clean := setupMemUfs(t)
 	defer clean()
 
 	c := []byte("hello")