From a53858010b576291eda47035fbaa77ab40bf33c7 Mon Sep 17 00:00:00 2001
From: "Bryan A. S" <bryanasdev000@gmail.com>
Date: Thu, 5 May 2022 11:42:44 -0300
Subject: [PATCH] nixos/zfs: introduce option to control hibernation

---
 .../from_md/release-notes/rl-2211.section.xml       | 12 ++++++++++++
 nixos/doc/manual/release-notes/rl-2211.section.md   |  2 ++
 nixos/modules/tasks/filesystems/zfs.nix             | 13 +++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/nixos/doc/manual/from_md/release-notes/rl-2211.section.xml b/nixos/doc/manual/from_md/release-notes/rl-2211.section.xml
index 1af4ce4bf9803..2c65f78789321 100644
--- a/nixos/doc/manual/from_md/release-notes/rl-2211.section.xml
+++ b/nixos/doc/manual/from_md/release-notes/rl-2211.section.xml
@@ -847,6 +847,18 @@
           <literal>hardware.saleae-logic.package</literal>.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          ZFS module will not allow hibernation by default, this is a
+          safety measure to prevent data loss cases like the ones
+          described at
+          <link xlink:href="https://github.com/openzfs/zfs/issues/260">OpenZFS/260</link>
+          and
+          <link xlink:href="https://github.com/openzfs/zfs/issues/12842">OpenZFS/12842</link>.
+          Use the <literal>boot.zfs.allowHibernation</literal> option to
+          configure this behaviour.
+        </para>
+      </listitem>
       <listitem>
         <para>
           The Redis module now disables RDB persistence when
diff --git a/nixos/doc/manual/release-notes/rl-2211.section.md b/nixos/doc/manual/release-notes/rl-2211.section.md
index b5adc0d8a363a..338ef119a99c8 100644
--- a/nixos/doc/manual/release-notes/rl-2211.section.md
+++ b/nixos/doc/manual/release-notes/rl-2211.section.md
@@ -274,6 +274,8 @@ Available as [services.patroni](options.html#opt-services.patroni.enable).
 
 - A new module was added for the Saleae Logic device family, providing the options `hardware.saleae-logic.enable` and `hardware.saleae-logic.package`.
 
+- ZFS module will not allow hibernation by default, this is a safety measure to prevent data loss cases like the ones described at [OpenZFS/260](https://github.com/openzfs/zfs/issues/260) and [OpenZFS/12842](https://github.com/openzfs/zfs/issues/12842). Use the `boot.zfs.allowHibernation` option to configure this behaviour.
+
 - The Redis module now disables RDB persistence when `services.redis.servers.<name>.save = []` instead of using the Redis default.
 
 - Neo4j was updated from version 3 to version 4. See this [migration guide](https://neo4j.com/docs/upgrade-migration-guide/current/) on how to migrate your Neo4j instance.
diff --git a/nixos/modules/tasks/filesystems/zfs.nix b/nixos/modules/tasks/filesystems/zfs.nix
index 96222f3b4f645..4b4f4cc801aba 100644
--- a/nixos/modules/tasks/filesystems/zfs.nix
+++ b/nixos/modules/tasks/filesystems/zfs.nix
@@ -226,6 +226,15 @@ in
           '';
       };
 
+      allowHibernation = mkOption {
+        type = types.bool;
+        default = false;
+        description = lib.mdDoc ''
+          Allow hibernation support, this may be a unsafe option depending on your
+          setup. Make sure to NOT use Swap on ZFS.
+        '';
+      };
+
       extraPools = mkOption {
         type = types.listOf types.str;
         default = [];
@@ -498,6 +507,10 @@ in
 
       boot = {
         kernelModules = [ "zfs" ];
+        # https://github.com/openzfs/zfs/issues/260
+        # https://github.com/openzfs/zfs/issues/12842
+        # https://github.com/NixOS/nixpkgs/issues/106093
+        kernelParams = lib.optionals (!config.boot.zfs.allowHibernation) [ "nohibernate" ];
 
         extraModulePackages = [
           (if config.boot.zfs.enableUnstable then