Report cleanup failures on the upload directory itself

main.go

@@ -796,6 +796,12 @@ func collectExpiredFiles(root string, duration time.Duration) ([]string, error)
 
 	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
+			// A failure on root itself means the sweep saw nothing at all — an
+			// unmounted or unreadable volume — so let it reach the caller
+			// instead of logging it as one more skipped path.
+			if path == root {
+				return err
+			}
 			log.Printf("Cleanup: skipping %q: %v", path, err)
 			return nil
 		}
@@ -825,8 +831,13 @@ func collectEmptyDirs(root string) ([]string, error) {
 
 	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
 		// d is nil when the root itself cannot be read, so this check must
-		// come first.
+		// come first. That case also means the sweep saw nothing at all — an
+		// unmounted or unreadable volume — so let it reach the caller instead
+		// of logging it as one more skipped path.
 		if err != nil {
+			if path == root {
+				return err
+			}
 			log.Printf("Cleanup: skipping %q: %v", path, err)
 			return nil
 		}