From a36922f81daefbc05dae8a7f152f6003e210dd5a Mon Sep 17 00:00:00 2001
From: chn <chn@chn.moe>
Date: Fri, 14 Jul 2023 16:57:57 +0800
Subject: [PATCH] =?UTF-8?q?=E6=95=B4=E7=90=86=E5=AE=8C=E6=88=90=20filesyst?=
 =?UTF-8?q?em?=
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---
 flake.nix                    |  3 ++-
 modules/boot/chn-PC.nix      | 30 +-------------------------
 modules/boot/fileSystems.nix | 42 +++++++++++++++++++++++++-----------
 3 files changed, 33 insertions(+), 42 deletions(-)

diff --git a/flake.nix b/flake.nix
index a207352e..0bc4d274 100644
--- a/flake.nix
+++ b/flake.nix
@@ -136,7 +136,7 @@
 												btrfs =
 												{
 													"/dev/disk/by-uuid/02e426ec-cfa2-4a18-b3a5-57ef04d66614"."/" = "/boot";
-													"/dev/mapper/root"."/nix" = "/nix";
+													"/dev/mapper/root" = { "/nix" = "/nix"; "/nix/rootfs/current" = "/"; };
 												};
 											};
 											decrypt.auto =
@@ -148,6 +148,7 @@
 												"ARRAY /dev/md/swap metadata=1.2 name=chn-PC:swap UUID=2b546b8d:e38007c8:02990dd1:df9e23a4";
 											swap = [ "/dev/mapper/swap" ];
 											resume = "/dev/mapper/swap";
+											rollingRootfs = { device = "/dev/mapper/root"; path = "/nix/rootfs"; };
 										};
 									};}
 								)
diff --git a/modules/boot/chn-PC.nix b/modules/boot/chn-PC.nix
index ef6a34cb..33d153c1 100644
--- a/modules/boot/chn-PC.nix
+++ b/modules/boot/chn-PC.nix
@@ -3,12 +3,6 @@ inputs:
 	config =
 	{
 		# filesystem mount
-		fileSystems."/" =
-		{
-			device = "/dev/mapper/root";
-			fsType = "btrfs";
-			options = [ "subvol=nix/rootfs/current" "compress-force=zstd" ];
-		};
 		# sudo btrfs fi mkswapfile --size 64g --uuid clear swap
 		# sudo btrfs inspect-internal map-swapfile -r swap
 		# sudo mdadm --create /dev/md/swap --level 0 --raid-devices 2 /dev/nvme1n1p5 /dev/nvme0n1p5
@@ -99,29 +93,7 @@ inputs:
 		# initrd, luks
 		boot.initrd =
 		{
-			systemd =
-			{
-				enable = true;
-				services.create-current-rootfs =
-				{
-					wantedBy = [ "local-fs-pre.target" ];
-					after = [ "cryptsetup.target" ];
-					before = [ "local-fs-pre.target" ];
-					unitConfig.DefaultDependencies = false;
-					serviceConfig.Type = "oneshot";
-					script =
-					''
-						mount /dev/mapper/root /mnt -m
-						if [ -f /mnt/nix/rootfs/current/.timestamp ]
-						then
-							mv /mnt/nix/rootfs/current /mnt/nix/rootfs/$(cat /mnt/nix/rootfs/current/.timestamp)
-						fi
-						btrfs subvolume create /mnt/nix/rootfs/current
-						echo $(date '+%Y%m%d%H%M%S') > /mnt/nix/rootfs/current/.timestamp
-						umount /mnt
-					'';
-				};
-			};
+			systemd.enable = true;
 			# modules in initrd
 			# modprobe --show-depends
 			availableKernelModules =
diff --git a/modules/boot/fileSystems.nix b/modules/boot/fileSystems.nix
index fc3941f8..8223b103 100644
--- a/modules/boot/fileSystems.nix
+++ b/modules/boot/fileSystems.nix
@@ -18,18 +18,11 @@ inputs:
 		swap = mkOption { type = types.listOf types.nonEmptyStr; };
 		resume = mkOption { type = types.nullOr (types.str or (types.submodule { options =
 			{ device = mkOption { type = types.nonEmptyStr; }; offset = mkOption { type = types.ints.unsigned; }; }; })); };
-		# cleanRootfs = mkOption { type = types.nullOr
-
-		# swap and resume
-		# swap != resume.device if swap is a file
-		# swap = mkOption { type = types.nullOr types.str; };
-		# resume =
-		# {
-		# 	device = mkOption { type = types.nullOr types.str; };
-		# 	# sudo btrfs fi mkswapfile --size 64g --uuid clear swap
-		# 	# sudo btrfs inspect-internal map-swapfile -r swap
-		# 	offset = mkOption { type = types.nullOr types.ints.unsigned; };
-		# };
+		rollingRootfs = mkOption { type = types.nullOr (types.submodule { options =
+		{
+			device = mkOption { type = types.nonEmptyStr; };
+			path = mkOption { type = types.nonEmptyStr; };
+		}; }); };
 	};
 	config =
 	{
@@ -91,6 +84,31 @@ inputs:
 				if inputs.config.nixos.fileSystems.mdadm != null then
 					{ services.swraid = { enable = true; mdadmConf = inputs.config.nixos.fileSystems.mdadm; }; }
 				else {}
+			)
+			// (
+				if inputs.config.nixos.fileSystems.rollingRootfs != null then
+				{
+					systemd.services.roll-rootfs =
+					{
+						wantedBy = [ "local-fs-pre.target" ];
+						after = [ "cryptsetup.target" ];
+						before = [ "local-fs-pre.target" ];
+						unitConfig.DefaultDependencies = false;
+						serviceConfig.Type = "oneshot";
+						script = let inherit (inputs.config.nixos.fileSystems.rollingRootfs) device path; in
+						''
+							mount ${device} /mnt
+							if [ -f /mnt${path}/current/.timestamp ]
+							then
+								mv /mnt${path}/current /mnt${path}/$(cat /mnt${path}/current/.timestamp)
+							fi
+							btrfs subvolume create /mnt${path}/current
+							echo $(date '+%Y%m%d%H%M%S') > /mnt${path}/current/.timestamp
+							umount /mnt
+						'';
+					};
+				}
+				else {}
 			);
 		}
 		// (