Let UnionFs expose 3 cache drop functions publically.

Test for behavior of deletion cache drop too.

unionfs/unionfs.go

@@ -720,10 +720,17 @@ func (me *UnionFs) Rename(src string, dst string) (code fuse.Status) {
 	return code
 }
 
-func (me *UnionFs) DropCaches() {
-	log.Println("Forced cache drop on", me.name)
+// TODO - a DropBranchCache which takes a list of names.
+
+func (me *UnionFs) DropBranchCache() {
 	me.branchCache.DropAll()
+}
+
+func (me *UnionFs) DropDeletionCache() {
 	me.deletionCache.DropCache()
+}
+
+func (me *UnionFs) DropSubFsCaches() {
 	for _, fs := range me.fileSystems {
 		a, code := fs.GetAttr(_DROP_CACHE)
 		if code.Ok() && a.IsRegular() {
@@ -739,7 +746,10 @@ func (me *UnionFs) DropCaches() {
 func (me *UnionFs) Open(name string, flags uint32) (fuseFile fuse.File, status fuse.Status) {
 	if name == _DROP_CACHE {
 		if flags&fuse.O_ANYWRITE != 0 {
-			me.DropCaches()
+			log.Println("Forced cache drop on", me.name)
+			me.DropBranchCache()
+			me.DropDeletionCache()
+			me.DropSubFsCaches()
 		}
 		return fuse.NewDevNullFile(), fuse.OK
 	}

unionfs/unionfs_test.go

@@ -44,10 +44,12 @@ func setupUfs(t *testing.T) (workdir string, cleanup func()) {
 		NewCachingFileSystem(fuse.NewLoopbackFileSystem(wd+"/ro"), 0))
 	ufs := NewUnionFs("testFs", fses, testOpts)
 
+	// We configure timeouts are smaller, so we can check for
+	// UnionFs's cache consistency.
 	opts := &fuse.FileSystemOptions{
-		EntryTimeout:    entryTtl,
-		AttrTimeout:     entryTtl,
-		NegativeTimeout: entryTtl,
+		EntryTimeout:    .5 * entryTtl,
+		AttrTimeout:     .5 * entryTtl,
+		NegativeTimeout: .5 * entryTtl,
 	}
 
 	state, _, err := fuse.MountFileSystem(wd+"/mount", ufs, opts)
@@ -541,6 +543,43 @@ func Readdirnames(dir string) ([]string, os.Error) {
 	return f.Readdirnames(-1)
 }
 
+func TestDropDeletionCache(t *testing.T) {
+	t.Log("TestDropDeletionCache")
+	wd, clean := setupUfs(t)
+	defer clean()
+
+	err := ioutil.WriteFile(wd+"/ro/file", []byte("bla"), 0644)
+	CheckSuccess(err)
+	_, err = os.Lstat(wd + "/mount/file")
+	CheckSuccess(err)
+	err = os.Remove(wd + "/mount/file")
+	CheckSuccess(err)
+	fi, _ := os.Lstat(wd + "/mount/file")
+	if fi != nil {
+		t.Fatal("Lstat() should have failed", fi)
+	}
+
+	names, err := Readdirnames(wd + "/rw/DELETIONS")
+	CheckSuccess(err)
+	if len(names) != 1 {
+		t.Fatal("unexpected names", names)
+	}
+	os.Remove(wd + "/rw/DELETIONS/" + names[0])
+	fi, _ = os.Lstat(wd + "/mount/file")
+	if fi != nil {
+		t.Fatal("Lstat() should have failed", fi)
+	}
+
+	// Expire kernel entry.
+	time.Sleep(0.6e9 * entryTtl)
+	err = ioutil.WriteFile(wd+"/mount/.drop_cache", []byte(""), 0644)
+	CheckSuccess(err)
+	_, err = os.Lstat(wd + "/mount/file")
+	if err != nil {
+		t.Fatal("Lstat() should have succeeded", err)
+	}
+}
+
 func TestDropCache(t *testing.T) {
 	t.Log("TestDropCache")
 	wd, clean := setupUfs(t)