allow modTime to be changed even before all writers are closed (fixes #1197 -- again)

cmd/mount/file.go

@@ -21,6 +21,7 @@ type File struct {
 	mu             sync.RWMutex // protects the following
 	o              fs.Object    // NB o may be nil if file is being written
 	writers        int          // number of writers for this file
+	pendingModTime time.Time    // will be applied once o becomes available, i.e. after file was written
 }
 
 // newFile creates a new File
@@ -59,6 +60,12 @@ func (f *File) Attr(ctx context.Context, a *fuse.Attr) error {
 	// if o is nil it isn't valid yet, so return the size so far
 	if f.o == nil {
 		a.Size = uint64(atomic.LoadInt64(&f.size))
+		if !noModTime && !f.pendingModTime.IsZero() {
+			a.Atime = f.pendingModTime
+			a.Mtime = f.pendingModTime
+			a.Ctime = f.pendingModTime
+			a.Crtime = f.pendingModTime
+		}
 	} else {
 		a.Size = uint64(f.o.Size())
 		if !noModTime {
@@ -83,34 +90,45 @@ func (f *File) Setattr(ctx context.Context, req *fuse.SetattrRequest, resp *fuse
 		return nil
 	}
 
-	// if o is nil it isn't valid yet
-	o, err := f.waitForValidObject()
-	if err != nil {
-		return err
-	}
-
 	f.mu.Lock()
 	defer f.mu.Unlock()
 
-	var newTime time.Time
 	if req.Valid.MtimeNow() {
-		newTime = time.Now()
+		f.pendingModTime = time.Now()
 	} else if req.Valid.Mtime() {
-		newTime = req.Mtime
+		f.pendingModTime = req.Mtime
 	}
 
-	if !newTime.IsZero() {
+	if f.o != nil {
-		err := o.SetModTime(newTime)
+		return f.applyPendingModTime()
+	}
+
+	// queue up for later, hoping f.o becomes available
+	return nil
+}
+
+// call with the mutex held
+func (f *File) applyPendingModTime() error {
+	defer func() { f.pendingModTime = time.Time{} }()
+
+	if f.pendingModTime.IsZero() {
+		return nil
+	}
+
+	if f.o == nil {
+		return errors.New("Cannot apply ModTime, file object is not available")
+	}
+
+	err := f.o.SetModTime(f.pendingModTime)
 	switch err {
 	case nil:
-			fs.Debugf(o, "File.Setattr ModTime OK")
+		fs.Debugf(f.o, "File.applyPendingModTime OK")
 	case fs.ErrorCantSetModTime:
 		// do nothing, in order to not break "touch somefile" if it exists already
 	default:
-			fs.Errorf(o, "File.Setattr ModTime error: %v", err)
+		fs.Errorf(f.o, "File.applyPendingModTime error: %v", err)
 		return err
 	}
-	}
 
 	return nil
 }
@@ -125,6 +143,7 @@ func (f *File) setObject(o fs.Object) {
 	f.mu.Lock()
 	defer f.mu.Unlock()
 	f.o = o
+	_ = f.applyPendingModTime()
 	f.d.addObject(o, f)
 }
 

cmd/mount/file_test.go

@@ -28,3 +28,30 @@ func TestFileModTime(t *testing.T) {
 
 	run.rm(t, "file")
 }
+
+func TestFileModTimeWithOpenWriters(t *testing.T) {
+	run.skipIfNoFUSE(t)
+
+	mtime := time.Date(2012, 11, 18, 17, 32, 31, 0, time.UTC)
+	filepath := run.path("cp-archive-test")
+
+	f, err := os.Create(filepath)
+	require.NoError(t, err)
+
+	_, err = f.Write([]byte{104, 105})
+	require.NoError(t, err)
+
+	err = os.Chtimes(filepath, mtime, mtime)
+	require.NoError(t, err)
+
+	err = f.Close()
+	require.NoError(t, err)
+
+	info, err := os.Stat(filepath)
+	require.NoError(t, err)
+
+	// avoid errors because of timezone differences
+	assert.Equal(t, info.ModTime().Unix(), mtime.Unix())
+
+	run.rm(t, "cp-archive-test")
+}