vfs: fix incorrect modtime for mv into mount with --vfs-cache-modes write

When a file has its modtime set while it is open we delay setting the
modtime until the file is closed.

The file is then uploaded in Flush. In Release we check the cached
file has been uploaded by comparing modtimes and or hashes and upload
it again if it has changed.

Before this change we forgot to change the time on the cached file
when we updated the time file on the object, so this mean that Release
reset the time to the wrong time and uploaded the file again on
remotes which don't support hashes (eg crypt).

The fix was to set the modtime of the cached file at the same time we
set the modtime of the remote object. This means that the files check
as identical in Release so it doesn't try to upload the file.

This means that we avoid a double upload and the modtime is correct.

See: https://forum.rclone.org/t/modification-time-with-vfs-cache/13906/8

vfs/cache.go

@@ -381,6 +381,15 @@ func (c *cache) removeDir(dir string) bool {
 	return false
 }
 
+// setModTime should be called to set the modification time of the cache file
+func (c *cache) setModTime(name string, modTime time.Time) {
+	osPath := c.toOSPath(name)
+	err := os.Chtimes(osPath, modTime, modTime)
+	if err != nil {
+		fs.Errorf(name, "Failed to set modification time of cached file: %v", err)
+	}
+}
+
 // cleanUp empties the cache of everything
 func (c *cache) cleanUp() error {
 	return os.RemoveAll(c.root)

vfs/file.go

@@ -88,11 +88,17 @@ func (f *File) Name() (name string) {
 	return f.leaf
 }
 
+// _path returns the full path of the file
+// use when lock is held
+func (f *File) _path() string {
+	return path.Join(f.d.path, f.leaf)
+}
+
 // Path returns the full path of the file
 func (f *File) Path() string {
 	f.mu.RLock()
 	defer f.mu.RUnlock()
-	return path.Join(f.d.path, f.leaf)
+	return f._path()
 }
 
 // osPath returns the full path of the file in the cache in OS format
@@ -372,6 +378,12 @@ func (f *File) _applyPendingModTime() error {
 		return errors.New("Cannot apply ModTime, file object is not available")
 	}
 
+	// set the time of the file in the cache
+	if f.d.vfs.Opt.CacheMode != CacheModeOff {
+		f.d.vfs.cache.setModTime(f._path(), f.pendingModTime)
+	}
+
+	// set the time of the object
 	err := f.o.SetModTime(context.TODO(), f.pendingModTime)
 	switch err {
 	case nil:

vfs/read_write_test.go

@@ -2,6 +2,7 @@ package vfs
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
@@ -687,7 +688,12 @@ func TestRWFileModTimeWithOpenWriters(t *testing.T) {
 	err = fh.Node().SetModTime(mtime)
 	require.NoError(t, err)
 
-	err = fh.Close()
+	// Using Flush/Release to mimic mount instead of Close
+
+	err = fh.Flush()
+	require.NoError(t, err)
+
+	err = fh.Release()
 	require.NoError(t, err)
 
 	info, err := vfs.Stat("file1")
@@ -695,8 +701,11 @@ func TestRWFileModTimeWithOpenWriters(t *testing.T) {
 
 	if r.Fremote.Precision() != fs.ModTimeNotSupported {
 		// avoid errors because of timezone differences
-		assert.Equal(t, info.ModTime().Unix(), mtime.Unix())
+		assert.Equal(t, info.ModTime().Unix(), mtime.Unix(), fmt.Sprintf("Time mismatch: %v != %v", info.ModTime(), mtime))
 	}
+
+	file1 := fstest.NewItem("file1", "hi", mtime)
+	fstest.CheckItems(t, r.Fremote, file1)
 }
 
 func TestRWCacheRename(t *testing.T) {