From b2a106f8ed84b948cbde5031ddc0942e709b8e1e Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Thu, 1 Aug 2024 15:41:09 -0400
Subject: [PATCH 01/10] zfs: Add topology attribute to zpool

---
 lib/default.nix     |   1 +
 lib/types/zpool.nix | 118 ++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 110 insertions(+), 9 deletions(-)

diff --git a/lib/default.nix b/lib/default.nix
index f4337f9..39753d4 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -195,6 +195,7 @@ let
             || isAttrsOfSubmodule o
             # TODO don't hardcode diskoLib.subType options.
             || n == "content" || n == "partitions" || n == "datasets" || n == "swap"
+            || n == "topology"
         );
       in
       lib.toShellVars
diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index f690c98..055ad84 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -1,4 +1,20 @@
 { config, options, lib, diskoLib, rootMountPoint, ... }:
+let
+  modeOptions = [
+    ""
+    "mirror"
+    "raidz"
+    "raidz2"
+    "raidz3"
+  ];
+  format_output = (mode: members: ''
+    entries+=("${mode}=${
+      lib.concatMapStringsSep " "
+      (d: "/dev/disk/by-partlabel/disk-${d}-zfs") members
+    }")
+  '');
+  format_vdev = (vdev: format_output vdev.mode vdev.members);
+in
 {
   options = {
     name = lib.mkOption {
@@ -13,13 +29,7 @@
       description = "Type";
     };
     mode = lib.mkOption {
-      type = lib.types.enum [
-        ""
-        "mirror"
-        "raidz"
-        "raidz2"
-        "raidz3"
-      ];
+      type = lib.types.enum (modeOptions ++ [ "prescribed" ]);
       default = "";
       description = "Mode of the ZFS pool";
     };
@@ -50,6 +60,55 @@
       });
       description = "List of datasets to define";
     };
+    topology = lib.mkOption {
+      type =
+        let
+          vdev = lib.types.submodule ({ name, ... }: {
+            options = {
+              mode = lib.mkOption {
+                type = lib.types.enum modeOptions;
+                default = "";
+                description = "mode of the zfs vdev";
+              };
+              members = lib.mkOption {
+                type = lib.types.listOf lib.types.str;
+                description = "Members of the vdev";
+              };
+            };
+          });
+          parent = config;
+        in
+        lib.types.nullOr
+          (lib.types.submodule
+            ({ config, name, ... }: {
+              options = {
+                type = lib.mkOption {
+                  type = lib.types.enum [ "zfs_topology" ];
+                  default = "zfs_topology";
+                  internal = true;
+                  description = "Type";
+                };
+                # zfs disk types
+                vdev = lib.mkOption {
+                  type = lib.types.listOf vdev;
+                  default = [ ];
+                  description = "A list of storage vdevs";
+                };
+                special = lib.mkOption {
+                  type = lib.types.nullOr vdev;
+                  default = null;
+                  description = "A list of devices for the special vdev";
+                };
+                cache = lib.mkOption {
+                  type = lib.types.nullOr lib.types.str;
+                  default = null;
+                  description = "The cache device";
+                };
+              };
+            }));
+      default = null;
+      description = "Topology of the ZFS pool";
+    };
     _meta = lib.mkOption {
       internal = true;
       readOnly = true;
@@ -84,11 +143,52 @@
             fi
           done
           if [ $continue -eq 1 ]; then
+            topology=""
+            # For shell check
+            mode="${config.mode}"
+            if [ $mode != "prescribed" ]; then
+              ${if config.topology == null then
+                ''topology="${config.mode} \"''${zfs_devices}\""''
+              else
+                ''
+                echo "topology cannot be set when mode != 'prescribed', skipping creating zpool ${config.name}" >&2
+                continue=0
+                ''
+              }
+            else
+              entries=()
+              ${lib.concatMapStrings format_vdev config.topology.vdev}
+              ${lib.optionalString (config.topology.special != null)
+                  (format_output "special ${config.topology.special.mode}" config.topology.special.members)}
+              ${lib.optionalString (config.topology.cache != null)
+                  (format_output "cache" [config.topology.cache])}
+              all_devices=()
+              for line in "''${entries[@]}"; do
+                # lineformat is mode=device1 device2 device3
+                mode=''${line%%=*}
+                devs=''${line#*=}
+                IFS=' ' read -r -a devices <<< "$devs"
+                all_devices+=("''${devices[@]}")
+                # shellcheck disable=SC2089
+                topology+=" ''${mode} ''${devices[*]}"
+              done
+              # all_devices sorted should equal zfs_devices sorted
+              all_devices_list=$(echo "''${all_devices[*]}" | tr ' ' '\n' | sort)
+              zfs_devices_list=$(echo "''${zfs_devices[*]}" | tr ' ' '\n' | sort)
+              if [[ "$all_devices_list" != "$zfs_devices_list" ]]; then
+                echo "not all disks accounted for, skipping creating zpool ${config.name}" >&2
+                diff  <(echo "$all_devices_list" ) <(echo "$zfs_devices_list") >&2
+                continue=0
+              fi
+            fi
+          fi
+          if [ $continue -eq 1 ]; then
+            # shellcheck disable=SC2090
             zpool create -f ${config.name} \
-              -R ${rootMountPoint} ${config.mode} \
+              -R ${rootMountPoint} \
               ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} \
               ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-O ${n}=${v}") config.rootFsOptions)} \
-              "''${zfs_devices[@]}"
+              ''${topology:+ $topology}
             if [[ $(zfs get -H mounted ${config.name} | cut -f3) == "yes" ]]; then
               zfs unmount ${config.name}
             fi

From 6bebcc728e85efb22b639a1ac308e90764201f0d Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Thu, 1 Aug 2024 15:59:33 -0400
Subject: [PATCH 02/10] tidy: move relevant variables and format script block

---
 lib/types/zpool.nix | 165 +++++++++++++++++++++++---------------------
 1 file changed, 85 insertions(+), 80 deletions(-)

diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index 055ad84..d3fcda4 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -7,13 +7,6 @@ let
     "raidz2"
     "raidz3"
   ];
-  format_output = (mode: members: ''
-    entries+=("${mode}=${
-      lib.concatMapStringsSep " "
-      (d: "/dev/disk/by-partlabel/disk-${d}-zfs") members
-    }")
-  '');
-  format_vdev = (vdev: format_output vdev.mode vdev.members);
 in
 {
   options = {
@@ -119,83 +112,95 @@ in
     };
     _create = diskoLib.mkCreateOption {
       inherit config options;
-      default = ''
-        readarray -t zfs_devices < <(cat "$disko_devices_dir"/zfs_${config.name})
-        # Try importing the pool without mounting anything if it exists.
-        # This allows us to set mounpoints.
-        if zpool import -N -f '${config.name}' || zpool list '${config.name}'; then
-          echo "not creating zpool ${config.name} as a pool with that name already exists" >&2
-        else
-          continue=1
-          for dev in "''${zfs_devices[@]}"; do
-            if ! blkid "$dev" >/dev/null; then
-              # blkid fails, so device seems empty
-              :
-            elif (blkid "$dev" -o export | grep '^PTUUID='); then
-              echo "device $dev already has a partuuid, skipping creating zpool ${config.name}" >&2
-              continue=0
-            elif (blkid "$dev" -o export | grep '^TYPE=zfs_member'); then
-              # zfs_member is a zfs partition, so we try to add the device to the pool
-              :
-            elif (blkid "$dev" -o export | grep '^TYPE='); then
-              echo "device $dev already has a partition, skipping creating zpool ${config.name}" >&2
-              continue=0
-            fi
-          done
-          if [ $continue -eq 1 ]; then
-            topology=""
-            # For shell check
-            mode="${config.mode}"
-            if [ $mode != "prescribed" ]; then
-              ${if config.topology == null then
-                ''topology="${config.mode} \"''${zfs_devices}\""''
+      default =
+        let
+          format_output = (mode: members: ''
+            entries+=("${mode}=${
+              lib.concatMapStringsSep " "
+              (d: "/dev/disk/by-partlabel/disk-${d}-zfs") members
+            }")
+          '');
+          format_vdev = (vdev: format_output vdev.mode vdev.members);
+          hasTopology = config.topology != null;
+        in
+        ''
+          readarray -t zfs_devices < <(cat "$disko_devices_dir"/zfs_${config.name})
+          # Try importing the pool without mounting anything if it exists.
+          # This allows us to set mounpoints.
+          if zpool import -N -f '${config.name}' || zpool list '${config.name}'; then
+            echo "not creating zpool ${config.name} as a pool with that name already exists" >&2
+          else
+            continue=1
+            for dev in "''${zfs_devices[@]}"; do
+              if ! blkid "$dev" >/dev/null; then
+                # blkid fails, so device seems empty
+                :
+              elif (blkid "$dev" -o export | grep '^PTUUID='); then
+                echo "device $dev already has a partuuid, skipping creating zpool ${config.name}" >&2
+                continue=0
+              elif (blkid "$dev" -o export | grep '^TYPE=zfs_member'); then
+                # zfs_member is a zfs partition, so we try to add the device to the pool
+                :
+              elif (blkid "$dev" -o export | grep '^TYPE='); then
+                echo "device $dev already has a partition, skipping creating zpool ${config.name}" >&2
+                continue=0
+              fi
+            done
+            if [ $continue -eq 1 ]; then
+              topology=""
+              # For shell check
+              mode="${config.mode}"
+              if [ $mode != "prescribed" ]; then
+                ${if hasTopology then
+                  ''topology="${config.mode} \"''${zfs_devices}\""''
+                else
+                  ''
+                  echo "topology cannot be set when mode != 'prescribed', skipping creating zpool ${config.name}" >&2
+                  continue=0
+                  ''
+                }
               else
-                ''
-                echo "topology cannot be set when mode != 'prescribed', skipping creating zpool ${config.name}" >&2
-                continue=0
-                ''
-              }
-            else
-              entries=()
-              ${lib.concatMapStrings format_vdev config.topology.vdev}
-              ${lib.optionalString (config.topology.special != null)
-                  (format_output "special ${config.topology.special.mode}" config.topology.special.members)}
-              ${lib.optionalString (config.topology.cache != null)
-                  (format_output "cache" [config.topology.cache])}
-              all_devices=()
-              for line in "''${entries[@]}"; do
-                # lineformat is mode=device1 device2 device3
-                mode=''${line%%=*}
-                devs=''${line#*=}
-                IFS=' ' read -r -a devices <<< "$devs"
-                all_devices+=("''${devices[@]}")
-                # shellcheck disable=SC2089
-                topology+=" ''${mode} ''${devices[*]}"
-              done
-              # all_devices sorted should equal zfs_devices sorted
-              all_devices_list=$(echo "''${all_devices[*]}" | tr ' ' '\n' | sort)
-              zfs_devices_list=$(echo "''${zfs_devices[*]}" | tr ' ' '\n' | sort)
-              if [[ "$all_devices_list" != "$zfs_devices_list" ]]; then
-                echo "not all disks accounted for, skipping creating zpool ${config.name}" >&2
-                diff  <(echo "$all_devices_list" ) <(echo "$zfs_devices_list") >&2
-                continue=0
+                entries=()
+                ${lib.optionalString (hasTopology && config.topology.vdev != null)
+                    (lib.concatMapStrings format_vdev config.topology.vdev)}
+                ${lib.optionalString (hasTopology && config.topology.special != null)
+                    (format_output "special ${config.topology.special.mode}" config.topology.special.members)}
+                ${lib.optionalString (hasTopology && config.topology.cache != null)
+                    (format_output "cache" [config.topology.cache])}
+                all_devices=()
+                for line in "''${entries[@]}"; do
+                  # lineformat is mode=device1 device2 device3
+                  mode=''${line%%=*}
+                  devs=''${line#*=}
+                  IFS=' ' read -r -a devices <<< "$devs"
+                  all_devices+=("''${devices[@]}")
+                  # shellcheck disable=SC2089
+                  topology+=" ''${mode} ''${devices[*]}"
+                done
+                # all_devices sorted should equal zfs_devices sorted
+                all_devices_list=$(echo "''${all_devices[*]}" | tr ' ' '\n' | sort)
+                zfs_devices_list=$(echo "''${zfs_devices[*]}" | tr ' ' '\n' | sort)
+                if [[ "$all_devices_list" != "$zfs_devices_list" ]]; then
+                  echo "not all disks accounted for, skipping creating zpool ${config.name}" >&2
+                  diff  <(echo "$all_devices_list" ) <(echo "$zfs_devices_list") >&2
+                  continue=0
+                fi
+              fi
+            fi
+            if [ $continue -eq 1 ]; then
+              # shellcheck disable=SC2090
+              zpool create -f ${config.name} \
+                -R ${rootMountPoint} \
+                ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} \
+                ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-O ${n}=${v}") config.rootFsOptions)} \
+                ''${topology:+ $topology}
+              if [[ $(zfs get -H mounted ${config.name} | cut -f3) == "yes" ]]; then
+                zfs unmount ${config.name}
               fi
             fi
           fi
-          if [ $continue -eq 1 ]; then
-            # shellcheck disable=SC2090
-            zpool create -f ${config.name} \
-              -R ${rootMountPoint} \
-              ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} \
-              ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-O ${n}=${v}") config.rootFsOptions)} \
-              ''${topology:+ $topology}
-            if [[ $(zfs get -H mounted ${config.name} | cut -f3) == "yes" ]]; then
-              zfs unmount ${config.name}
-            fi
-          fi
-        fi
-        ${lib.concatMapStrings (dataset: dataset._create) (lib.attrValues config.datasets)}
-      '';
+          ${lib.concatMapStrings (dataset: dataset._create) (lib.attrValues config.datasets)}
+        '';
     };
     _mount = diskoLib.mkMountOption {
       inherit config options;

From f484389085ea1ebd697516510d944dec55515288 Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Thu, 1 Aug 2024 16:00:11 -0400
Subject: [PATCH 03/10] example: barebones example of zfs-with-vdevs

---
 example/zfs-with-vdevs.nix | 114 +++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 example/zfs-with-vdevs.nix

diff --git a/example/zfs-with-vdevs.nix b/example/zfs-with-vdevs.nix
new file mode 100644
index 0000000..cd85add
--- /dev/null
+++ b/example/zfs-with-vdevs.nix
@@ -0,0 +1,114 @@
+{
+  disko.devices = {
+    disk = {
+      x = {
+        type = "disk";
+        device = "/dev/sdx";
+        content = {
+          type = "gpt";
+          partitions = {
+            ESP = {
+              size = "64M";
+              type = "EF00";
+              content = {
+                type = "filesystem";
+                format = "vfat";
+                mountpoint = "/boot";
+              };
+            };
+            zfs = {
+              size = "100%";
+              content = {
+                type = "zfs";
+                pool = "zroot";
+              };
+            };
+          };
+        };
+      };
+      y = {
+        type = "disk";
+        device = "/dev/sdy";
+        content = {
+          type = "gpt";
+          partitions = {
+            zfs = {
+              size = "100%";
+              content = {
+                type = "zfs";
+                pool = "zroot";
+              };
+            };
+          };
+        };
+      };
+      z = {
+        type = "disk";
+        device = "/dev/sdz";
+        content = {
+          type = "gpt";
+          partitions = {
+            zfs = {
+              size = "100%";
+              content = {
+                type = "zfs";
+                pool = "zroot";
+              };
+            };
+          };
+        };
+      };
+      cache = {
+        type = "disk";
+        device = "/dev/sdc";
+        content = {
+          type = "gpt";
+          partitions = {
+            zfs = {
+              size = "100%";
+              content = {
+                type = "zfs";
+                pool = "zroot";
+              };
+            };
+          };
+        };
+      };
+    };
+    zpool = {
+      zroot = {
+        type = "zpool";
+        mode = "prescribed";
+        rootFsOptions = {
+          compression = "zstd";
+          "com.sun:auto-snapshot" = "false";
+        };
+        mountpoint = "/";
+
+        topology = {
+          type = "zfs_topology";
+          vdev = [
+            {
+              mode = "mirror";
+              members = [ "x" "y" ];
+            }
+          ];
+          special = {
+            members = [ "z" ];
+          };
+          cache = "cache";
+        };
+
+        datasets = {
+            # See examples/zfs.nix for more comprehensive usage.
+            zfs_fs = {
+              type = "zfs_fs";
+              mountpoint = "/zfs_fs";
+              options."com.sun:auto-snapshot" = "true";
+            };
+        };
+      };
+    };
+  };
+}
+

From 8d071db09b1cc5f4a31940a53bd287f63e915052 Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Mon, 5 Aug 2024 12:11:35 -0400
Subject: [PATCH 04/10] test: fix and add stub test for zfs-with-vdevs

---
 example/zfs-with-vdevs.nix | 15 +++++++--------
 example/zfs.nix            |  1 -
 lib/types/zpool.nix        |  8 +++-----
 tests/zfs-with-vdevs.nix   | 24 ++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 14 deletions(-)
 create mode 100644 tests/zfs-with-vdevs.nix

diff --git a/example/zfs-with-vdevs.nix b/example/zfs-with-vdevs.nix
index cd85add..0058ac5 100644
--- a/example/zfs-with-vdevs.nix
+++ b/example/zfs-with-vdevs.nix
@@ -60,7 +60,7 @@
       };
       cache = {
         type = "disk";
-        device = "/dev/sdc";
+        device = "/dev/vdc";
         content = {
           type = "gpt";
           partitions = {
@@ -100,15 +100,14 @@
         };
 
         datasets = {
-            # See examples/zfs.nix for more comprehensive usage.
-            zfs_fs = {
-              type = "zfs_fs";
-              mountpoint = "/zfs_fs";
-              options."com.sun:auto-snapshot" = "true";
-            };
+          # See examples/zfs.nix for more comprehensive usage.
+          zfs_fs = {
+            type = "zfs_fs";
+            mountpoint = "/zfs_fs";
+            options."com.sun:auto-snapshot" = "true";
+          };
         };
       };
     };
   };
 }
-
diff --git a/example/zfs.nix b/example/zfs.nix
index 933386a..4d09061 100644
--- a/example/zfs.nix
+++ b/example/zfs.nix
@@ -100,4 +100,3 @@
     };
   };
 }
-
diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index d3fcda4..b7e35d3 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -150,9 +150,9 @@ in
               topology=""
               # For shell check
               mode="${config.mode}"
-              if [ $mode != "prescribed" ]; then
-                ${if hasTopology then
-                  ''topology="${config.mode} \"''${zfs_devices}\""''
+              if [ "$mode" != "prescribed" ]; then
+                ${if !hasTopology then
+                  ''topology="${config.mode} ''${zfs_devices[*]}"''
                 else
                   ''
                   echo "topology cannot be set when mode != 'prescribed', skipping creating zpool ${config.name}" >&2
@@ -174,7 +174,6 @@ in
                   devs=''${line#*=}
                   IFS=' ' read -r -a devices <<< "$devs"
                   all_devices+=("''${devices[@]}")
-                  # shellcheck disable=SC2089
                   topology+=" ''${mode} ''${devices[*]}"
                 done
                 # all_devices sorted should equal zfs_devices sorted
@@ -188,7 +187,6 @@ in
               fi
             fi
             if [ $continue -eq 1 ]; then
-              # shellcheck disable=SC2090
               zpool create -f ${config.name} \
                 -R ${rootMountPoint} \
                 ${lib.concatStringsSep " " (lib.mapAttrsToList (n: v: "-o ${n}=${v}") config.options)} \
diff --git a/tests/zfs-with-vdevs.nix b/tests/zfs-with-vdevs.nix
new file mode 100644
index 0000000..5f8c67d
--- /dev/null
+++ b/tests/zfs-with-vdevs.nix
@@ -0,0 +1,24 @@
+{ pkgs ? import <nixpkgs> { }
+, diskoLib ? pkgs.callPackage ../lib { }
+}:
+diskoLib.testLib.makeDiskoTest {
+  inherit pkgs;
+  name = "zfs-with-vdevs";
+  disko-config = ../example/zfs-with-vdevs.nix;
+  extraInstallerConfig.networking.hostId = "8425e349";
+  extraSystemConfig = {
+    networking.hostId = "8425e349";
+  };
+  extraTestScript = ''
+    def assert_property(ds, property, expected_value):
+        out = machine.succeed(f"zfs get -H {property} {ds} -o value").rstrip()
+        assert (
+            out == expected_value
+        ), f"Expected {property}={expected_value} on {ds}, got: {out}"
+
+    assert_property("zroot", "compression", "zstd")
+    assert_property("zroot/zfs_fs", "com.sun:auto-snapshot", "true")
+    assert_property("zroot/zfs_fs", "compression", "zstd")
+    machine.succeed("mountpoint /zfs_fs");
+  '';
+}

From 540cd416f689b2eaf482752bec1f0c0417b37537 Mon Sep 17 00:00:00 2001
From: zerox <el@mathematica.uz>
Date: Mon, 26 Aug 2024 09:48:53 +0500
Subject: [PATCH 05/10] zfs: add ability to specify full path of to the disk.

---
 lib/types/zpool.nix | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index b7e35d3..f6167be 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -117,7 +117,7 @@ in
           format_output = (mode: members: ''
             entries+=("${mode}=${
               lib.concatMapStringsSep " "
-              (d: "/dev/disk/by-partlabel/disk-${d}-zfs") members
+              (d: if lib.strings.hasPrefix "/" d then d else "/dev/disk/by-partlabel/disk-${d}-zfs") members
             }")
           '');
           format_vdev = (vdev: format_output vdev.mode vdev.members);

From cc2e247193513a378fe0457374d4de7823aede1f Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Mon, 26 Aug 2024 12:24:41 -0400
Subject: [PATCH 06/10] zfs: make topology a mode type

---
 example/zfs-with-vdevs.nix |  31 +++++----
 lib/default.nix            |   2 +-
 lib/types/zpool.nix        | 135 ++++++++++++++++++-------------------
 3 files changed, 83 insertions(+), 85 deletions(-)

diff --git a/example/zfs-with-vdevs.nix b/example/zfs-with-vdevs.nix
index 0058ac5..864cbbd 100644
--- a/example/zfs-with-vdevs.nix
+++ b/example/zfs-with-vdevs.nix
@@ -78,27 +78,26 @@
     zpool = {
       zroot = {
         type = "zpool";
-        mode = "prescribed";
+        mode = {
+          topology = {
+            vdev = [
+              {
+                mode = "mirror";
+                members = [ "x" "y" ];
+              }
+            ];
+            special = {
+              members = [ "z" ];
+            };
+            cache = "cache";
+          };
+        };
+
         rootFsOptions = {
           compression = "zstd";
           "com.sun:auto-snapshot" = "false";
         };
         mountpoint = "/";
-
-        topology = {
-          type = "zfs_topology";
-          vdev = [
-            {
-              mode = "mirror";
-              members = [ "x" "y" ];
-            }
-          ];
-          special = {
-            members = [ "z" ];
-          };
-          cache = "cache";
-        };
-
         datasets = {
           # See examples/zfs.nix for more comprehensive usage.
           zfs_fs = {
diff --git a/lib/default.nix b/lib/default.nix
index 39753d4..31acc9c 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -195,7 +195,7 @@ let
             || isAttrsOfSubmodule o
             # TODO don't hardcode diskoLib.subType options.
             || n == "content" || n == "partitions" || n == "datasets" || n == "swap"
-            || n == "topology"
+            || n == "mode"
         );
       in
       lib.toShellVars
diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index f6167be..415f221 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -22,8 +22,61 @@ in
       description = "Type";
     };
     mode = lib.mkOption {
-      type = lib.types.enum (modeOptions ++ [ "prescribed" ]);
       default = "";
+      type = (lib.types.enum modeOptions) // (lib.types.attrsOf (diskoLib.subType {
+        types = {
+          topology =
+            let
+              vdev = lib.types.submodule ({ name, ... }: {
+                options = {
+                  mode = lib.mkOption {
+                    type = lib.types.enum modeOptions;
+                    default = "";
+                    description = "mode of the zfs vdev";
+                  };
+                  members = lib.mkOption {
+                    type = lib.types.listOf lib.types.str;
+                    description = "Members of the vdev";
+                  };
+                };
+              });
+              parent = config;
+            in
+            lib.types.submodule
+              ({ config, name, ... }: {
+                options = {
+                  type = lib.mkOption {
+                    type = lib.types.enum [ "topology" ];
+                    default = "topology";
+                    internal = true;
+                    description = "Type";
+                  };
+                  # zfs disk types
+                  vdev = lib.mkOption {
+                    type = lib.types.listOf vdev;
+                    default = [ ];
+                    description = "A list of storage vdevs";
+                    example = [{
+                      mode = "mirror";
+                      members = [ "x" "y" ];
+                    }];
+                  };
+                  special = lib.mkOption {
+                    type = lib.types.nullOr vdev;
+                    default = null;
+                    description = "A list of devices for the special vdev";
+                  };
+                  cache = lib.mkOption {
+                    type = lib.types.nullOr lib.types.str;
+                    default = null;
+                    description = "The cache device";
+                  };
+                  # TODO: Consider
+                };
+              });
+        };
+        extraArgs.parent = config;
+      }));
       description = "Mode of the ZFS pool";
     };
     options = lib.mkOption {
@@ -53,55 +106,6 @@ in
       });
       description = "List of datasets to define";
     };
-    topology = lib.mkOption {
-      type =
-        let
-          vdev = lib.types.submodule ({ name, ... }: {
-            options = {
-              mode = lib.mkOption {
-                type = lib.types.enum modeOptions;
-                default = "";
-                description = "mode of the zfs vdev";
-              };
-              members = lib.mkOption {
-                type = lib.types.listOf lib.types.str;
-                description = "Members of the vdev";
-              };
-            };
-          });
-          parent = config;
-        in
-        lib.types.nullOr
-          (lib.types.submodule
-            ({ config, name, ... }: {
-              options = {
-                type = lib.mkOption {
-                  type = lib.types.enum [ "zfs_topology" ];
-                  default = "zfs_topology";
-                  internal = true;
-                  description = "Type";
-                };
-                # zfs disk types
-                vdev = lib.mkOption {
-                  type = lib.types.listOf vdev;
-                  default = [ ];
-                  description = "A list of storage vdevs";
-                };
-                special = lib.mkOption {
-                  type = lib.types.nullOr vdev;
-                  default = null;
-                  description = "A list of devices for the special vdev";
-                };
-                cache = lib.mkOption {
-                  type = lib.types.nullOr lib.types.str;
-                  default = null;
-                  description = "The cache device";
-                };
-              };
-            }));
-      default = null;
-      description = "Topology of the ZFS pool";
-    };
     _meta = lib.mkOption {
       internal = true;
       readOnly = true;
@@ -114,14 +118,16 @@ in
       inherit config options;
       default =
         let
-          format_output = (mode: members: ''
+          formatOutput = (mode: members: ''
             entries+=("${mode}=${
               lib.concatMapStringsSep " "
               (d: if lib.strings.hasPrefix "/" d then d else "/dev/disk/by-partlabel/disk-${d}-zfs") members
             }")
           '');
-          format_vdev = (vdev: format_output vdev.mode vdev.members);
-          hasTopology = config.topology != null;
+          formatVdev = (vdev: formatOutput vdev.mode vdev.members);
+          hasTopology = builtins.isString config.mode;
+          mode = if hasTopology then config.mode else "prescribed";
+          topology = if hasTopology then config.mode.topology else { };
         in
         ''
           readarray -t zfs_devices < <(cat "$disko_devices_dir"/zfs_${config.name})
@@ -149,24 +155,17 @@ in
             if [ $continue -eq 1 ]; then
               topology=""
               # For shell check
-              mode="${config.mode}"
+              mode="${mode}"
               if [ "$mode" != "prescribed" ]; then
-                ${if !hasTopology then
-                  ''topology="${config.mode} ''${zfs_devices[*]}"''
-                else
-                  ''
-                  echo "topology cannot be set when mode != 'prescribed', skipping creating zpool ${config.name}" >&2
-                  continue=0
-                  ''
-                }
+                topology="${mode} ''${zfs_devices[*]}"
               else
                 entries=()
-                ${lib.optionalString (hasTopology && config.topology.vdev != null)
-                    (lib.concatMapStrings format_vdev config.topology.vdev)}
-                ${lib.optionalString (hasTopology && config.topology.special != null)
-                    (format_output "special ${config.topology.special.mode}" config.topology.special.members)}
-                ${lib.optionalString (hasTopology && config.topology.cache != null)
-                    (format_output "cache" [config.topology.cache])}
+                ${lib.optionalString (hasTopology && topology.vdev != null)
+                    (lib.concatMapStrings formatVdev topology.vdev)}
+                ${lib.optionalString (hasTopology && topology.special != null)
+                    (formatOutput "special ${topology.special.mode}" topology.special.members)}
+                ${lib.optionalString (hasTopology && topology.cache != null)
+                    (formatOutput "cache" [topology.cache])}
                 all_devices=()
                 for line in "''${entries[@]}"; do
                   # lineformat is mode=device1 device2 device3

From ea3ce722ea9bd569cee40d797f115f1e7489cc8b Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Mon, 26 Aug 2024 13:03:25 -0400
Subject: [PATCH 07/10] zfs: fix test and add documentation

---
 example/zfs-with-vdevs.nix |  1 +
 lib/types/zfs.nix          |  1 +
 lib/types/zpool.nix        | 38 ++++++++++++++++++++++++++------------
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/example/zfs-with-vdevs.nix b/example/zfs-with-vdevs.nix
index 864cbbd..caaa4a0 100644
--- a/example/zfs-with-vdevs.nix
+++ b/example/zfs-with-vdevs.nix
@@ -80,6 +80,7 @@
         type = "zpool";
         mode = {
           topology = {
+            type = "topology";
             vdev = [
               {
                 mode = "mirror";
diff --git a/lib/types/zfs.nix b/lib/types/zfs.nix
index 9aa8577..2b43623 100644
--- a/lib/types/zfs.nix
+++ b/lib/types/zfs.nix
@@ -53,3 +53,4 @@
     };
   };
 }
+
diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index 415f221..858f456 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -1,9 +1,11 @@
 { config, options, lib, diskoLib, rootMountPoint, ... }:
 let
+  # TODO: Consider expanding to handle `disk` `file` and `draid` mode options.
   modeOptions = [
     ""
     "mirror"
     "raidz"
+    "raidz1"
     "raidz2"
     "raidz3"
   ];
@@ -32,7 +34,7 @@ in
                   mode = lib.mkOption {
                     type = lib.types.enum modeOptions;
                     default = "";
-                    description = "mode of the zfs vdev";
+                    description = "Mode of the zfs vdev";
                   };
                   members = lib.mkOption {
                     type = lib.types.listOf lib.types.str;
@@ -51,27 +53,39 @@ in
                     internal = true;
                     description = "Type";
                   };
-                  # zfs disk types
+                  # zfs device types
                   vdev = lib.mkOption {
                     type = lib.types.listOf vdev;
                     default = [ ];
-                    description = "A list of storage vdevs";
+                    description = ''
+                      A list of storage vdevs. See
+                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Virtual_Devices_(vdevs)
+                      for details.
+                    '';
                     example = [{
                       mode = "mirror";
-                      members = [ "x" "y" ];
+                      members = [ "x" "y" "/dev/sda1" ];
                     }];
                   };
                   special = lib.mkOption {
                     type = lib.types.nullOr vdev;
                     default = null;
-                    description = "A list of devices for the special vdev";
+                    description = ''
+                      A vdev definition for a special device. See
+                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#special
+                      for details.
+                    '';
                   };
                   cache = lib.mkOption {
-                    type = lib.types.nullOr lib.types.str;
+                    type = lib.types.listOf lib.types.str;
                     default = null;
-                    description = "The cache device";
+                    description = ''
+                      A dedicated zfs cache device (L2ARC). See
+                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Cache_Devices
+                      for details.
+                    '';
                   };
-                  # TODO: Consider
+                  # TODO: Consider supporting log, spare, and dedup options.
                 };
               });
         };
@@ -125,8 +139,8 @@ in
             }")
           '');
           formatVdev = (vdev: formatOutput vdev.mode vdev.members);
-          hasTopology = builtins.isString config.mode;
-          mode = if hasTopology then config.mode else "prescribed";
+          hasTopology = !(builtins.isString config.mode);
+          mode = if !hasTopology then config.mode else "prescribed";
           topology = if hasTopology then config.mode.topology else { };
         in
         ''
@@ -164,8 +178,8 @@ in
                     (lib.concatMapStrings formatVdev topology.vdev)}
                 ${lib.optionalString (hasTopology && topology.special != null)
                     (formatOutput "special ${topology.special.mode}" topology.special.members)}
-                ${lib.optionalString (hasTopology && topology.cache != null)
-                    (formatOutput "cache" [topology.cache])}
+                ${lib.optionalString (hasTopology && topology.cache != [])
+                    (formatOutput "cache" topology.cache)}
                 all_devices=()
                 for line in "''${entries[@]}"; do
                   # lineformat is mode=device1 device2 device3

From c9d3bc37553140444ad51df29a231aece29f97ea Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Mon, 26 Aug 2024 14:00:44 -0400
Subject: [PATCH 08/10] fix: properly apply oneOf

---
 example/zfs-with-vdevs.nix |   2 +-
 example/zfs.nix            |   1 +
 lib/types/zfs.nix          |   1 -
 lib/types/zpool.nix        | 131 +++++++++++++++++++------------------
 4 files changed, 69 insertions(+), 66 deletions(-)

diff --git a/example/zfs-with-vdevs.nix b/example/zfs-with-vdevs.nix
index caaa4a0..a61680a 100644
--- a/example/zfs-with-vdevs.nix
+++ b/example/zfs-with-vdevs.nix
@@ -90,7 +90,7 @@
             special = {
               members = [ "z" ];
             };
-            cache = "cache";
+            cache = [ "cache" ];
           };
         };
 
diff --git a/example/zfs.nix b/example/zfs.nix
index 4d09061..933386a 100644
--- a/example/zfs.nix
+++ b/example/zfs.nix
@@ -100,3 +100,4 @@
     };
   };
 }
+
diff --git a/lib/types/zfs.nix b/lib/types/zfs.nix
index 2b43623..9aa8577 100644
--- a/lib/types/zfs.nix
+++ b/lib/types/zfs.nix
@@ -53,4 +53,3 @@
     };
   };
 }
-
diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index 858f456..2ddbb0e 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -25,72 +25,75 @@ in
     };
     mode = lib.mkOption {
       default = "";
-      type = (lib.types.enum modeOptions) // (lib.types.attrsOf (diskoLib.subType {
-        types = {
-          topology =
-            let
-              vdev = lib.types.submodule ({ name, ... }: {
-                options = {
-                  mode = lib.mkOption {
-                    type = lib.types.enum modeOptions;
-                    default = "";
-                    description = "Mode of the zfs vdev";
+      type = (lib.types.oneOf [
+        (lib.types.enum modeOptions)
+        (lib.types.attrsOf (diskoLib.subType {
+          types = {
+            topology =
+              let
+                vdev = lib.types.submodule ({ name, ... }: {
+                  options = {
+                    mode = lib.mkOption {
+                      type = lib.types.enum modeOptions;
+                      default = "";
+                      description = "Mode of the zfs vdev";
+                    };
+                    members = lib.mkOption {
+                      type = lib.types.listOf lib.types.str;
+                      description = "Members of the vdev";
+                    };
                   };
-                  members = lib.mkOption {
-                    type = lib.types.listOf lib.types.str;
-                    description = "Members of the vdev";
+                });
+                parent = config;
+              in
+              lib.types.submodule
+                ({ config, name, ... }: {
+                  options = {
+                    type = lib.mkOption {
+                      type = lib.types.enum [ "topology" ];
+                      default = "topology";
+                      internal = true;
+                      description = "Type";
+                    };
+                    # zfs device types
+                    vdev = lib.mkOption {
+                      type = lib.types.listOf vdev;
+                      default = [ ];
+                      description = ''
+                        A list of storage vdevs. See
+                        https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Virtual_Devices_(vdevs)
+                        for details.
+                      '';
+                      example = [{
+                        mode = "mirror";
+                        members = [ "x" "y" "/dev/sda1" ];
+                      }];
+                    };
+                    special = lib.mkOption {
+                      type = lib.types.nullOr vdev;
+                      default = null;
+                      description = ''
+                        A vdev definition for a special device. See
+                        https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#special
+                        for details.
+                      '';
+                    };
+                    cache = lib.mkOption {
+                      type = lib.types.listOf lib.types.str;
+                      default = null;
+                      description = ''
+                        A dedicated zfs cache device (L2ARC). See
+                        https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Cache_Devices
+                        for details.
+                      '';
+                    };
+                    # TODO: Consider supporting log, spare, and dedup options.
                   };
-                };
-              });
-              parent = config;
-            in
-            lib.types.submodule
-              ({ config, name, ... }: {
-                options = {
-                  type = lib.mkOption {
-                    type = lib.types.enum [ "topology" ];
-                    default = "topology";
-                    internal = true;
-                    description = "Type";
-                  };
-                  # zfs device types
-                  vdev = lib.mkOption {
-                    type = lib.types.listOf vdev;
-                    default = [ ];
-                    description = ''
-                      A list of storage vdevs. See
-                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Virtual_Devices_(vdevs)
-                      for details.
-                    '';
-                    example = [{
-                      mode = "mirror";
-                      members = [ "x" "y" "/dev/sda1" ];
-                    }];
-                  };
-                  special = lib.mkOption {
-                    type = lib.types.nullOr vdev;
-                    default = null;
-                    description = ''
-                      A vdev definition for a special device. See
-                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#special
-                      for details.
-                    '';
-                  };
-                  cache = lib.mkOption {
-                    type = lib.types.listOf lib.types.str;
-                    default = null;
-                    description = ''
-                      A dedicated zfs cache device (L2ARC). See
-                      https://openzfs.github.io/openzfs-docs/man/master/7/zpoolconcepts.7.html#Cache_Devices
-                      for details.
-                    '';
-                  };
-                  # TODO: Consider supporting log, spare, and dedup options.
-                };
-              });
-        };
-        extraArgs.parent = config;
-      }));
+                });
+          };
+          extraArgs.parent = config;
+        }))
+      ]);
       description = "Mode of the ZFS pool";
     };
     options = lib.mkOption {

From 071306e76a7d1a05d0ffa4251a466c3d300e268d Mon Sep 17 00:00:00 2001
From: Dylan Madisetti <dylan@madisetti.me>
Date: Mon, 26 Aug 2024 14:13:07 -0400
Subject: [PATCH 09/10] tidy: apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Jörg Thalheim <Mic92@users.noreply.github.com>
---
 lib/types/zpool.nix | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/types/zpool.nix b/lib/types/zpool.nix
index 2ddbb0e..0510b94 100644
--- a/lib/types/zpool.nix
+++ b/lib/types/zpool.nix
@@ -135,16 +135,16 @@ in
       inherit config options;
       default =
         let
-          formatOutput = (mode: members: ''
+          formatOutput = mode: members: ''
             entries+=("${mode}=${
               lib.concatMapStringsSep " "
               (d: if lib.strings.hasPrefix "/" d then d else "/dev/disk/by-partlabel/disk-${d}-zfs") members
             }")
-          '');
-          formatVdev = (vdev: formatOutput vdev.mode vdev.members);
+          '';
+          formatVdev = vdev: formatOutput vdev.mode vdev.members;
           hasTopology = !(builtins.isString config.mode);
-          mode = if !hasTopology then config.mode else "prescribed";
-          topology = if hasTopology then config.mode.topology else { };
+          mode = if hasTopology then "prescribed" else config.mode;
+          topology = lib.optionalAttrs hasTopology config.mode.topology;
         in
         ''
           readarray -t zfs_devices < <(cat "$disko_devices_dir"/zfs_${config.name})

From cf5d451adc87720753f5a85caac2c81e83550110 Mon Sep 17 00:00:00 2001
From: dylan madisetti <dylan@madisetti.me>
Date: Tue, 27 Aug 2024 08:29:31 -0400
Subject: [PATCH 10/10] test: Add cache specific test

---
 tests/zfs-with-vdevs.nix | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tests/zfs-with-vdevs.nix b/tests/zfs-with-vdevs.nix
index 5f8c67d..dbca4fc 100644
--- a/tests/zfs-with-vdevs.nix
+++ b/tests/zfs-with-vdevs.nix
@@ -16,6 +16,15 @@ diskoLib.testLib.makeDiskoTest {
             out == expected_value
         ), f"Expected {property}={expected_value} on {ds}, got: {out}"
 
+    # These fields are 0 if l2arc is disabled
+    assert (
+        machine.succeed(
+            "cat /proc/spl/kstat/zfs/arcstats"
+            " | grep '^l2_' | tr -s ' '"
+            " | cut -s -d ' ' -f3 | uniq"
+        ).strip() != "0"
+    ), "Excepted cache to be utilized."
+
     assert_property("zroot", "compression", "zstd")
     assert_property("zroot/zfs_fs", "com.sun:auto-snapshot", "true")
     assert_property("zroot/zfs_fs", "compression", "zstd")