fusefrontend: use DirIVCache in OpenDir()

Previously, OpenDir() did not use the cache at all, missing
an opportunity to speed up repeated directory reads.

1 files changed, 16 insertions, 10 deletions

diff --git a/internal/fusefrontend/fs_dir.go b/internal/fusefrontend/fs_dir.go
index 44a4ad2..211eeea 100644
--- a/internal/fusefrontend/fs_dir.go
+++ b/internal/fusefrontend/fs_dir.go
@@ -260,18 +260,24 @@ func (fs *FS) OpenDir(dirName string, context *fuse.Context) ([]fuse.DirEntry, f
 	// Get DirIV (stays nil if PlaintextNames is used)
 	var cachedIV []byte
 	if !fs.args.PlaintextNames {
-		// Read the DirIV once and use it for all later name decryptions
-		cachedIV, err = nametransform.ReadDirIV(cDirAbsPath)
-		if err != nil {
-			// This can happen during normal operation when the directory has
-			// been deleted concurrently. But it can also mean that the
-			// gocryptfs.diriv is missing due to an error, so log the event
-			// at "info" level.
-			tlog.Info.Printf("OpenDir: %v", err)
-			return nil, fuse.ToStatus(err)
+		cachedIV, _ = fs.nameTransform.DirIVCache.Lookup(dirName)
+		if cachedIV == nil {
+			// Read the DirIV from disk and store it in the cache
+			fs.dirIVLock.RLock()
+			cachedIV, err = nametransform.ReadDirIV(cDirAbsPath)
+			if err != nil {
+				fs.dirIVLock.RUnlock()
+				// This can happen during normal operation when the directory has
+				// been deleted concurrently. But it can also mean that the
+				// gocryptfs.diriv is missing due to an error, so log the event
+				// at "info" level.
+				tlog.Info.Printf("OpenDir: %v", err)
+				return nil, fuse.ToStatus(err)
+			}
+			fs.nameTransform.DirIVCache.Store(dirName, cachedIV, cDirName)
+			fs.dirIVLock.RUnlock()
 		}
 	}
-
 	// Decrypted directory entries
 	var plain []fuse.DirEntry
 	var errorCount int