Allow configuring vfs

lib/modules/rclone.nix

@@ -89,6 +89,44 @@ let
           default = "";
         };
 
+        vfs = {
+          enable = lib.mkEnableOption "Virtual File System";
+
+          mode = lib.mkOption {
+            type = lib.types.nullOr (lib.types.enum [
+              "minimal"
+              "writes"
+              "full"
+            ]);
+            description = "The cache mode to use.";
+            default = "full";
+          };
+
+          dirCacheTime = lib.mkOption {
+            type = lib.types.nullOr lib.types.str;
+            description = "The time to cache directory entries for.";
+            default = null;
+          };
+
+          pollInterval = lib.mkOption {
+            type = lib.types.nullOr lib.types.str;
+            description = "The time to wait between polling for changes.";
+            default = null;
+          };
+
+          bufferSize = lib.mkOption {
+            type = lib.types.nullOr lib.types.str;
+            description = "The maximum size of the buffer per size to allocate.";
+            default = null;
+          };
+
+          maxAge = lib.mkOption {
+            type = lib.types.nullOr lib.types.str;
+            description = "The maximum age of cached files to keep.";
+            default = null;
+          };
+        };
+
         extraArgs = lib.mkOption {
           type = lib.types.listOf lib.types.str;
           description = "A set of additional arguments to pass to `rclone mount`.";
@@ -115,7 +153,23 @@ let
               (name: path: "export ${name}=\"$(cat ${lib.escapeShellArg path})\"")
               config.secrets));
 
-        args = config.extraArgs;
+        args = config.extraArgs ++ (
+          let
+            vfs = config.vfs;
+          in (
+            lib.optionals vfs.enable
+              (builtins.attrValues (
+                lib.attrsets.concatMapAttrs
+                  (name: value:
+                    lib.optionalAttrs
+                      (value != null)
+                      { name = "--${name}=${lib.escapeShellArg value}"; })
+                  {
+                    vfs-cache-mode = vfs.mode;
+                    vfs-cache-poll-interval = vfs.pollInterval;
+                    vfs-cache-max-size = vfs.bufferSize;
+                    vfs-cache-max-age = vfs.maxAge;
+                  }))));
       };
     });
 
@@ -320,6 +374,12 @@ in {
         global = true;
       };
 
+      globalArgs = lib.mkOption {
+        type = lib.types.listOf lib.types.str;
+        description = "The arguments to pass to `rclone mount` for each configuration.";
+        default = [ ];
+      };
+
       configs = (builtins.mapAttrs
         (name: provider: lib.mkOption {
           type = lib.types.attrsOf (lib.types.submodule provider.module);
@@ -394,7 +454,9 @@ in {
                         ${sync.secretsScript}
                         mkdir -p ${sync.path}
                         mkdir -p /tmp/rclone
-                        ${lib.getExe pkgs.rclone} mount --config ${configFile} ${name}: ${sync.path}
+                        ${lib.getExe pkgs.rclone} mount ${
+                          builtins.concatStringsSep " " (cfg.globalArgs ++ sync.args)
+                        } --config ${configFile} ${name}: ${sync.path}
                       '';
                     in
                       (lib.getExe script);