From 9a82dd87f7bfa6be85ecd70e118811accdd04a4d Mon Sep 17 00:00:00 2001
From: Svein Ove Aas <sveina@gmail.com>
Date: Wed, 23 Dec 2015 00:29:47 +0100
Subject: [PATCH 1/2] zfs:Add zfs.devNodes option for zpool import -d

---
 nixos/modules/tasks/filesystems/zfs.nix | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/tasks/filesystems/zfs.nix b/nixos/modules/tasks/filesystems/zfs.nix
index dedd3f5ca451..14c6b05f95c7 100644
--- a/nixos/modules/tasks/filesystems/zfs.nix
+++ b/nixos/modules/tasks/filesystems/zfs.nix
@@ -73,6 +73,21 @@ in
         '';
       };
 
+      devNodes = mkOption {
+        type = types.path;
+        default = "/dev";
+        example = "/dev/disk/by-id";
+        description = ''
+          Name of directory from which to import ZFS devices.
+
+          Usually /dev works. However, ZFS import may fail if a device node is renamed.
+          It should therefore use stable device names, such as from /dev/disk/by-id.
+
+          The default remains /dev for 15.09, due to backwards compatibility concerns.
+          It will change to /dev/disk/by-id in the next NixOS release.
+        '';
+      };
+
       forceImportRoot = mkOption {
         type = types.bool;
         default = true;
@@ -214,7 +229,7 @@ in
             done
             ''] ++ (map (pool: ''
             echo "importing root ZFS pool \"${pool}\"..."
-            zpool import -d /dev/disk/by-id -N $ZFS_FORCE "${pool}"
+            zpool import -d ${cfgZfs.devNodes} -N $ZFS_FORCE "${pool}"
         '') rootPools));
       };
 
@@ -255,7 +270,7 @@ in
             };
             script = ''
               zpool_cmd="${zfsUserPkg}/sbin/zpool"
-              ("$zpool_cmd" list "${pool}" >/dev/null) || "$zpool_cmd" import -d /dev/disk/by-id -N ${optionalString cfgZfs.forceImportAll "-f"} "${pool}"
+              ("$zpool_cmd" list "${pool}" >/dev/null) || "$zpool_cmd" import -d ${cfgZfs.devNodes} -N ${optionalString cfgZfs.forceImportAll "-f"} "${pool}"
             '';
           };
       in listToAttrs (map createImportService dataPools) // {

From 7688206a0bfaddf950a1fb85b84fabdc1232e7f8 Mon Sep 17 00:00:00 2001
From: Svein Ove Aas <sveina@gmail.com>
Date: Wed, 23 Dec 2015 00:33:06 +0100
Subject: [PATCH 2/2] zfs:Change default for -d to /dev/disk/by-id

---
 nixos/modules/tasks/filesystems/zfs.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/nixos/modules/tasks/filesystems/zfs.nix b/nixos/modules/tasks/filesystems/zfs.nix
index 14c6b05f95c7..f4c42b162206 100644
--- a/nixos/modules/tasks/filesystems/zfs.nix
+++ b/nixos/modules/tasks/filesystems/zfs.nix
@@ -75,7 +75,7 @@ in
 
       devNodes = mkOption {
         type = types.path;
-        default = "/dev";
+        default = "/dev/disk/by-id";
         example = "/dev/disk/by-id";
         description = ''
           Name of directory from which to import ZFS devices.