fusefrontend: refactor dirIVCache

Simplify the code a bit.

internal/nametransform/diriv.go

@@ -92,8 +92,8 @@ func (be *NameTransform) EncryptPathDirIV(plainPath string, rootDir string) (cip
 	}
 	// Check if the DirIV is cached
 	parentDir := filepath.Dir(plainPath)
-	found, iv, cParentDir := be.DirIVCache.lookup(parentDir)
-	if found {
+	iv, cParentDir := be.DirIVCache.lookup(parentDir)
+	if iv != nil {
 		cBaseName := be.EncryptName(baseName, iv)
 		if be.longNames && len(cBaseName) > syscall.NAME_MAX {
 			cBaseName = HashLongName(cBaseName)

internal/nametransform/diriv_cache.go

@@ -2,42 +2,47 @@ package nametransform
 
 import "sync"
 
-// A simple one-entry DirIV cache
+// Single-entry DirIV cache. Stores the directory IV and the encrypted
+// path.
 type dirIVCache struct {
-	// Invalidated?
-	cleared bool
-	// The DirIV
-	iv []byte
 	// Directory the DirIV belongs to
 	dir string
+
+	// The DirIV
+	iv []byte
 	// Ecrypted version of "dir"
-	translatedDir string
-	// Synchronisation
-	lock sync.RWMutex
+	cDir string
+
+	// Invalidated?
+	cleared bool
+	sync.RWMutex
 }
 
 // lookup - fetch entry for "dir" from the cache
-func (c *dirIVCache) lookup(dir string) (bool, []byte, string) {
-	c.lock.RLock()
-	defer c.lock.RUnlock()
-	if !c.cleared && c.dir == dir {
-		return true, c.iv, c.translatedDir
+func (c *dirIVCache) lookup(dir string) ([]byte, string) {
+	c.RLock()
+	defer c.RUnlock()
+	if c.cleared || c.dir != dir {
+		return nil, ""
 	}
-	return false, nil, ""
+	return c.iv, c.cDir
 }
 
-// store - write entry for "dir" into the caches
-func (c *dirIVCache) store(dir string, iv []byte, translatedDir string) {
-	c.lock.Lock()
-	defer c.lock.Unlock()
+// store - write entry for "dir" into the cache
+func (c *dirIVCache) store(dir string, iv []byte, cDir string) {
+	c.Lock()
+	defer c.Unlock()
 	c.cleared = false
 	c.iv = iv
 	c.dir = dir
-	c.translatedDir = translatedDir
+	c.cDir = cDir
 }
 
+// Clear ... clear the cache.
+// Exported because it is called from fusefrontend when directories are
+// renamed or deleted.
 func (c *dirIVCache) Clear() {
-	c.lock.Lock()
-	defer c.lock.Unlock()
+	c.Lock()
+	defer c.Unlock()
 	c.cleared = true
 }