nixos/tasks/lvm: add dmeventd and lvmthin support

Introduce a pkgs.lvm2_dmeventd that contains dmeventd support, and
enable if services.lvm.dmeventd.enable is true.

nixos/modules/tasks/lvm.nix

@@ -1,17 +1,70 @@
 { config, lib, pkgs, ... }:
 
 with lib;
-
+let
-{
+  cfg = config.services.lvm;
-
+in {
-  ###### implementation
+  options.services.lvm = {
-
+    package = mkOption {
-  config = mkIf (!config.boot.isContainer) {
+      type = types.package;
-
+      default = if cfg.dmeventd.enable then pkgs.lvm2_dmeventd else pkgs.lvm2;
-    environment.systemPackages = [ pkgs.lvm2 ];
+      internal = true;
-
+      defaultText = "pkgs.lvm2";
-    services.udev.packages = [ pkgs.lvm2 ];
+      description = ''
-
+        This option allows you to override the LVM package that's used on the system
+        (udev rules, tmpfiles, systemd services).
+        Defaults to pkgs.lvm2, or pkgs.lvm2_dmeventd if dmeventd is enabled.
+      '';
+    };
+    dmeventd.enable = mkEnableOption "the LVM dmevent daemon";
+    boot.thin.enable = mkEnableOption "support for booting from ThinLVs";
   };
 
+  config = mkMerge [
+    (mkIf (!config.boot.isContainer) {
+      environment.etc."tmpfiles.d/lvm2.conf".source = "${cfg.package}/lib/tmpfiles.d/lvm2.conf";
+      environment.systemPackages = [ cfg.package ];
+      systemd.packages = [ cfg.package ];
+
+      # TODO: update once https://github.com/NixOS/nixpkgs/pull/93006 was merged
+      services.udev.packages = [ cfg.package.out ];
+    })
+    (mkIf cfg.dmeventd.enable {
+      systemd.sockets."dm-event".wantedBy = [ "sockets.target" ];
+      systemd.services."lvm2-monitor".wantedBy = [ "sysinit.target" ];
+
+      environment.etc."lvm/lvm.conf".text = ''
+        dmeventd/executable = "${cfg.package}/bin/dmeventd"
+      '';
+    })
+    (mkIf cfg.boot.thin.enable {
+      boot.initrd = {
+        kernelModules = [ "dm-snapshot" "dm-thin-pool" ];
+
+        extraUtilsCommands = ''
+          copy_bin_and_libs ${pkgs.thin-provisioning-tools}/bin/pdata_tools
+          copy_bin_and_libs ${pkgs.thin-provisioning-tools}/bin/thin_check
+        '';
+      };
+
+      environment.etc."lvm/lvm.conf".text = ''
+        global/thin_check_executable = "${pkgs.thin-provisioning-tools}/bin/thin_check"
+      '';
+    })
+    (mkIf (cfg.dmeventd.enable || cfg.boot.thin.enable) {
+      boot.initrd.preLVMCommands = ''
+          mkdir -p /etc/lvm
+          cat << EOF >> /etc/lvm/lvm.conf
+          ${optionalString cfg.boot.thin.enable ''
+            global/thin_check_executable = "$(command -v thin_check)"
+          ''}
+          ${optionalString cfg.dmeventd.enable ''
+            dmeventd/executable = "$(command -v false)"
+            activation/monitoring = 0
+          ''}
+          EOF
+      '';
+    })
+  ];
+
 }

pkgs/top-level/all-packages.nix

@@ -16817,7 +16817,7 @@ in
 
   directvnc = callPackage ../os-specific/linux/directvnc { };
 
-  dmraid = callPackage ../os-specific/linux/dmraid { };
+  dmraid = callPackage ../os-specific/linux/dmraid { lvm2 = lvm2_dmeventd; };
 
   drbd = callPackage ../os-specific/linux/drbd { };
 
@@ -17520,6 +17520,10 @@ in
   lsscsi = callPackage ../os-specific/linux/lsscsi { };
 
   lvm2 = callPackage ../os-specific/linux/lvm2 { };
+  lvm2_dmeventd = callPackage ../os-specific/linux/lvm2 {
+    enable_dmeventd = true;
+    enable_cmdlib = true;
+  };
 
   mbpfan = callPackage ../os-specific/linux/mbpfan { };