zfs_2_1: init at 2.1.13

This re-introduces the old stable ZFS version we had in the past following
the many predicted issues of ZFS 2.2.x series, that is much more stable
than any further ZFS version at the moment.

I am also removing myself from maintenance of any further ZFS versions as I am
planning to quit ZFS maintenance at some point.

In the meantime, for users like me who depend on ZFS for critical operations, here is a ZFS version
that is known to work for LTS kernels.

1 files changed, 19 insertions, 12 deletions

diff --git a/nixos/modules/tasks/filesystems/zfs.nix b/nixos/modules/tasks/filesystems/zfs.nix
index 4b6a5b6c12c1..72bc79f31b68 100644
--- a/nixos/modules/tasks/filesystems/zfs.nix
+++ b/nixos/modules/tasks/filesystems/zfs.nix
@@ -16,6 +16,7 @@ let
   cfgTrim = config.services.zfs.trim;
   cfgZED = config.services.zfs.zed;
 
+  selectModulePackage = package: config.boot.kernelPackages.${package.kernelModuleAttribute};
   inInitrd = any (fs: fs == "zfs") config.boot.initrd.supportedFilesystems;
   inSystem = any (fs: fs == "zfs") config.boot.supportedFilesystems;
 
@@ -210,11 +211,17 @@ in
   options = {
     boot.zfs = {
       package = mkOption {
-        readOnly = true;
         type = types.package;
-        default = if config.boot.zfs.enableUnstable then pkgs.zfsUnstable else pkgs.zfs;
-        defaultText = literalExpression "if config.boot.zfs.enableUnstable then pkgs.zfsUnstable else pkgs.zfs";
-        description = lib.mdDoc "Configured ZFS userland tools package.";
+        default = if cfgZfs.enableUnstable then pkgs.zfsUnstable else pkgs.zfs;
+        defaultText = literalExpression "if zfsUnstable is enabled then pkgs.zfsUnstable else pkgs.zfs";
+        description = lib.mdDoc "Configured ZFS userland tools package, use `pkgs.zfsUnstable` if you want to track the latest staging ZFS branch.";
+      };
+
+      modulePackage = mkOption {
+        internal = true; # It is supposed to be selected automatically, but can be overridden by expert users.
+        default = selectModulePackage cfgZfs.package;
+        type = types.package;
+        description = lib.mdDoc "Configured ZFS kernel module package.";
       };
 
       enabled = mkOption {
@@ -534,6 +541,10 @@ in
     (mkIf cfgZfs.enabled {
       assertions = [
         {
+          assertion = cfgZfs.modulePackage.version == cfgZfs.package.version;
+          message = "The kernel module and the userspace tooling versions are not matching, this is an unsupported usecase.";
+        }
+        {
           assertion = cfgZED.enableMail -> cfgZfs.package.enableMail;
           message = ''
             To allow ZED to send emails, ZFS needs to be configured to enable
@@ -571,18 +582,14 @@ in
         # https://github.com/NixOS/nixpkgs/issues/106093
         kernelParams = lib.optionals (!config.boot.zfs.allowHibernation) [ "nohibernate" ];
 
-        extraModulePackages = let
-          kernelPkg = if config.boot.zfs.enableUnstable then
-            config.boot.kernelPackages.zfsUnstable
-           else
-            config.boot.kernelPackages.zfs;
-        in [
-          (kernelPkg.override { inherit (cfgZfs) removeLinuxDRM; })
+        extraModulePackages = [
+          (cfgZfs.modulePackage.override { inherit (cfgZfs) removeLinuxDRM; })
         ];
       };
 
       boot.initrd = mkIf inInitrd {
-        kernelModules = [ "zfs" ] ++ optional (!cfgZfs.enableUnstable) "spl";
+        # spl has been removed in ≥ 2.2.0.
+        kernelModules = [ "zfs" ] ++ lib.optional (lib.versionOlder "2.2.0" version) "spl";
         extraUtilsCommands =
           mkIf (!config.boot.initrd.systemd.enable) ''
             copy_bin_and_libs ${cfgZfs.package}/sbin/zfs