From 1026c02f6d71e5ba8cc969d0b4ab743881f8a094 Mon Sep 17 00:00:00 2001
From: Orivej Desh <orivej@gmx.fr>
Date: Tue, 8 Dec 2020 16:38:30 +0000
Subject: [PATCH 1/2] zfs: fix build with linux-rt

---
 pkgs/os-specific/linux/zfs/default.nix | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/pkgs/os-specific/linux/zfs/default.nix b/pkgs/os-specific/linux/zfs/default.nix
index a83e554b6f0a..a2464aeb5865 100644
--- a/pkgs/os-specific/linux/zfs/default.nix
+++ b/pkgs/os-specific/linux/zfs/default.nix
@@ -176,6 +176,11 @@ let
         maintainers = with maintainers; [ hmenke jcumming jonringer wizeman fpletz globin mic92 ];
       };
     };
+
+  linux-rt-patch = fetchpatch {
+    url = "https://github.com/openzfs/zfs/commit/ab4fb9b74e9d089fc9a261c4f41e19697ad6a4ca.patch";
+    sha256 = "1nrxmb4rhrkgncav6dzwm66l0700fi72qkkcs0w6pkm850srws36";
+  };
 in {
   # also check if kernel version constraints in
   # ./nixos/modules/tasks/filesystems/zfs.nix needs
@@ -188,6 +193,8 @@ in {
     version = "2.0.0";
 
     sha256 = "1kriz6pg8wj98izvjc60wp23lgcp4k3mzhpkgj74np73rzgy6v8r";
+
+    extraPatches = [ linux-rt-patch ];
   };
 
   zfsUnstable = common {
@@ -198,5 +205,7 @@ in {
     version = "2.0.0";
 
     sha256 = "1kriz6pg8wj98izvjc60wp23lgcp4k3mzhpkgj74np73rzgy6v8r";
+
+    extraPatches = [ linux-rt-patch ];
   };
 }

From 4376b91b4067dc77b0a9a7ae3fe4ac20d0ff6f51 Mon Sep 17 00:00:00 2001
From: Orivej Desh <orivej@gmx.fr>
Date: Tue, 8 Dec 2020 15:23:51 +0000
Subject: [PATCH 2/2] linux-rt_5_9: export symbols needed by zfs

Upstream issue: https://github.com/openzfs/zfs/issues/11097#issuecomment-740682245
---
 .../linux/kernel/export-rt-sched-migrate.patch        | 11 +++++++++++
 pkgs/os-specific/linux/kernel/patches.nix             |  5 +++++
 pkgs/top-level/all-packages.nix                       |  1 +
 3 files changed, 17 insertions(+)
 create mode 100644 pkgs/os-specific/linux/kernel/export-rt-sched-migrate.patch

diff --git a/pkgs/os-specific/linux/kernel/export-rt-sched-migrate.patch b/pkgs/os-specific/linux/kernel/export-rt-sched-migrate.patch
new file mode 100644
index 000000000000..1d8ed6f712cb
--- /dev/null
+++ b/pkgs/os-specific/linux/kernel/export-rt-sched-migrate.patch
@@ -0,0 +1,11 @@
+Export linux-rt (PREEMPT_RT) specific symbols needed by ZFS.
+(Regular kernel provides them static inline in linux/preempt.h.)
+
+--- a/kernel/sched/core.c
++++ b/kernel/sched/core.c
+@@ -1812 +1812 @@ void migrate_disable(void)
+-EXPORT_SYMBOL_GPL(migrate_disable);
++EXPORT_SYMBOL(migrate_disable);
+@@ -1843 +1843 @@ void migrate_enable(void)
+-EXPORT_SYMBOL_GPL(migrate_enable);
++EXPORT_SYMBOL(migrate_enable);
diff --git a/pkgs/os-specific/linux/kernel/patches.nix b/pkgs/os-specific/linux/kernel/patches.nix
index 8ce1ac2b587c..e2805c315b8b 100644
--- a/pkgs/os-specific/linux/kernel/patches.nix
+++ b/pkgs/os-specific/linux/kernel/patches.nix
@@ -87,6 +87,11 @@
     };
   };
 
+  export-rt-sched-migrate = {
+    name = "export-rt-sched-migrate";
+    patch = ./export-rt-sched-migrate.patch;
+  };
+
   # patches from https://lkml.org/lkml/2019/7/15/1748
   mac_nvme_t2 = rec {
     name = "mac_nvme_t2";
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 6674a5612791..5a33e8a023d9 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -18363,6 +18363,7 @@ in
       kernelPatches.bridge_stp_helper
       kernelPatches.request_key_helper
       kernelPatches.export_kernel_fpu_functions."5.3"
+      kernelPatches.export-rt-sched-migrate
     ];
   };