erofs: use multithreading in mkfs when possible

modules/partitions.nix

@@ -21,9 +21,10 @@
 
       mkfsOptions = {
         erofs = [
-          # "-zzstd,6" # Zstd compression
+          "-zzstd,6" # Zstd compression
           "-T0" # Fixed timestamp for all files
-          "-Efragments,dedupe,ztailpacking" # Extended options
+          "-C65536" # 64 KiB cluster size
+          # "-Efragments,dedupe,ztailpacking" # Extra features
         ];
       };
 

overlays/default.nix

@@ -3,6 +3,7 @@ final: prev: {
   erofs-utils = prev.erofs-utils.overrideAttrs (old: {
     buildInputs = old.buildInputs ++ [ prev.zstd ];
     configureFlags = old.configureFlags ++ [
+      "--enable-multithreading"
       "--enable-zstd"
     ];
   });