fix: allocate full VG size to root LV when using Btrfs subvolumes on LVM

archinstall/lib/disk/default_layouts.py

@@ -397,8 +397,13 @@ async def suggest_lvm_layout(
 		(p.length for p in other_part),
 		Size(0, Unit.B, SectorSize.default()),
 	)
-	root_vol_size = process_root_partition_size(total_vol_available, SectorSize.default())
-	home_vol_size = total_vol_available - root_vol_size
+
+	if home_volume:
+		root_vol_size = process_root_partition_size(total_vol_available, SectorSize.default())
+		home_vol_size = total_vol_available - root_vol_size
+	else:
+		root_vol_size = total_vol_available
+		home_vol_size = Size(0, Unit.B, SectorSize.default())
 
 	lvm_vol_group = LvmVolumeGroup(vg_grp_name, pvs=other_part)
 
@@ -407,7 +412,7 @@ async def suggest_lvm_layout(
 		name='root',
 		fs_type=filesystem_type,
 		length=root_vol_size,
-		mountpoint=Path('/'),
+		mountpoint=Path('/') if not using_subvolumes else None,
 		btrfs_subvols=btrfs_subvols,
 		mount_options=mount_options,
 	)

archinstall/lib/models/device.py

@@ -262,6 +262,14 @@ def has_default_btrfs_vols(self) -> bool:
 				if any(subvol.is_default_root() for subvol in part.btrfs_subvols):
 					return True
 
+		if self.lvm_config:
+			for vol in self.lvm_config.get_all_volumes():
+				if not (vol.status in [ModificationStatus.CREATE, ModificationStatus.MODIFY] and vol.fs_type == FilesystemType.BTRFS):
+					continue
+
+				if any(subvol.is_default_root() for subvol in vol.btrfs_subvols):
+					return True
+
 		return False
 
 

tests/test_lvm_btrfs_layout.py

@@ -0,0 +1,90 @@
+import asyncio
+from pathlib import Path
+from unittest.mock import MagicMock
+
+from pytest import MonkeyPatch
+
+from archinstall.lib.disk.default_layouts import suggest_lvm_layout
+from archinstall.lib.menu.abstract_menu import MenuItem
+from archinstall.lib.models.device import (
+	BDevice,
+	DeviceModification,
+	DiskLayoutConfiguration,
+	DiskLayoutType,
+	FilesystemType,
+	ModificationStatus,
+	PartitionFlag,
+	PartitionModification,
+	PartitionType,
+	SectorSize,
+	Size,
+	Unit,
+)
+
+
+def test_suggest_lvm_layout_with_btrfs_subvolumes_uses_full_vg_size(
+	monkeypatch: MonkeyPatch,
+) -> None:
+	sector_size = SectorSize.default()
+	mock_bdevice = MagicMock(spec=BDevice)
+	mock_bdevice.device_info = MagicMock(path=Path('/dev/sda'))
+
+	boot_part = PartitionModification(
+		status=ModificationStatus.CREATE,
+		type=PartitionType.PRIMARY,
+		start=Size(1, Unit.MiB, sector_size),
+		length=Size(1, Unit.GiB, sector_size),
+		fs_type=FilesystemType.FAT32,
+		mountpoint=Path('/boot'),
+		flags=[PartitionFlag.BOOT, PartitionFlag.ESP],
+	)
+	pv_part = PartitionModification(
+		status=ModificationStatus.CREATE,
+		type=PartitionType.PRIMARY,
+		start=Size(1025, Unit.MiB, sector_size),
+		length=Size(500, Unit.GiB, sector_size),
+		fs_type=FilesystemType.EXT4,
+	)
+
+	dev_mod = DeviceModification(
+		device=mock_bdevice,
+		wipe=True,
+		partitions=[boot_part, pv_part],
+	)
+	disk_config = DiskLayoutConfiguration(
+		config_type=DiskLayoutType.Default,
+		device_modifications=[dev_mod],
+	)
+
+	class FakeConfirmation:
+		def __init__(self, **_kwargs: object) -> None:
+			pass
+
+		async def show(self) -> MagicMock:
+			res = MagicMock()
+			res.item.return_value = MenuItem.yes()
+			return res
+
+	async def fake_select_mount_options() -> list[str]:
+		return ['compress=zstd']
+
+	monkeypatch.setattr('archinstall.lib.disk.default_layouts.Confirmation', FakeConfirmation)
+	monkeypatch.setattr('archinstall.lib.disk.default_layouts.select_mount_options', fake_select_mount_options)
+
+	lvm_config = asyncio.run(
+		suggest_lvm_layout(
+			disk_config,
+			filesystem_type=FilesystemType.BTRFS,
+		)
+	)
+
+	disk_config.lvm_config = lvm_config
+
+	volumes = lvm_config.get_all_volumes()
+	assert len(volumes) == 1
+	root_vol = volumes[0]
+	assert root_vol.name == 'root'
+	assert root_vol.length == Size(500, Unit.GiB, sector_size)
+	assert root_vol.mountpoint is None
+	assert len(root_vol.btrfs_subvols) > 0
+	assert disk_config.has_default_btrfs_vols() is True