From 51d6cd005c6d1305a5b69ce1c613abd48013ff3b Mon Sep 17 00:00:00 2001
From: Max <max@privatevoid.net>
Date: Wed, 23 Aug 2023 17:02:22 +0200
Subject: [PATCH] modules/external-storage: add strictMounts to systemd service
 options

---
 modules/external-storage/default.nix         |  4 +++
 modules/external-storage/filesystem-type.nix |  4 +++
 modules/external-storage/strict-mounts.nix   | 27 ++++++++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 modules/external-storage/strict-mounts.nix

diff --git a/modules/external-storage/default.nix b/modules/external-storage/default.nix
index baa2cdf..ec23ff3 100644
--- a/modules/external-storage/default.nix
+++ b/modules/external-storage/default.nix
@@ -13,6 +13,10 @@ let
 in
 
 {
+  imports = [
+    ./strict-mounts.nix
+  ];
+
   options = {
     services.external-storage = {
       fileSystems = lib.mkOption {
diff --git a/modules/external-storage/filesystem-type.nix b/modules/external-storage/filesystem-type.nix
index e35a68f..af401e5 100644
--- a/modules/external-storage/filesystem-type.nix
+++ b/modules/external-storage/filesystem-type.nix
@@ -26,5 +26,9 @@ with lib;
       type = types.str;
       default = "default";
     };
+    dependentServices = mkOption {
+      type = with types; listOf str;
+      default = [];
+    };
   };
 }
diff --git a/modules/external-storage/strict-mounts.nix b/modules/external-storage/strict-mounts.nix
new file mode 100644
index 0000000..b304ac0
--- /dev/null
+++ b/modules/external-storage/strict-mounts.nix
@@ -0,0 +1,27 @@
+{ config, lib, ... }:
+
+let
+  cfg = config.services.external-storage;
+in
+
+with lib;
+{
+  options.systemd.services = mkOption {
+    type = with types; attrsOf (submodule ({ config, ... }: {
+      options.strictMounts = mkOption {
+        type = with types; listOf path;
+        default = [];
+      };
+      config = mkIf (config.strictMounts != []) (let
+        findFilesystemsFor = mount: pipe cfg.fileSystems [
+          (filterAttrs (_: fs: hasPrefix "${fs.mountpoint}/" "${mount}/"))
+          (mapAttrsToList (_: fs: "${fs.unitName}.service"))
+        ];
+        services = flatten (map findFilesystemsFor config.strictMounts);
+      in {
+        after = services;
+        bindsTo = services;
+      });
+    }));
+  };
+}