disk: NewPartitionTable can wrap plain partitions in LVM

Add a new parameter `lvmify` to `NewPartitionTable` that, if set to
`true`, will cause the root partition to be wrapped in LVM in case
it is not in a LVM volume group. Set this to `false` for now so no
actual change should happen anywhere. Layouts where the root is
directly on a LUKS container are not yet supported.
Add tests for this.

internal/disk/disk_test.go

@@ -66,7 +66,7 @@ func TestDisk_DynamicallyResizePartitionTable(t *testing.T) {
 	// math/rand is good enough in this case
 	/* #nosec G404 */
 	rng := rand.New(rand.NewSource(0))
-	newpt, err := NewPartitionTable(&pt, mountpoints, 1024, rng)
+	newpt, err := NewPartitionTable(&pt, mountpoints, 1024, false, rng)
 	assert.NoError(t, err)
 	assert.GreaterOrEqual(t, newpt.Size, expectedSize)
 }
@@ -358,7 +358,7 @@ func TestCreatePartitionTable(t *testing.T) {
 	rng := rand.New(rand.NewSource(13))
 	for name := range testPartitionTables {
 		pt := testPartitionTables[name]
-		mpt, err := NewPartitionTable(&pt, bp, uint64(13*1024*1024), rng)
+		mpt, err := NewPartitionTable(&pt, bp, uint64(13*1024*1024), false, rng)
 		assert.NoError(err, "Partition table generation failed: %s (%s)", name, err)
 		assert.NotNil(mpt, "Partition table generation failed: %s (nil partition table)", name)
 		assert.Greater(mpt.GetSize(), uint64(37*1024*1024*1024))
@@ -369,3 +369,33 @@ func TestCreatePartitionTable(t *testing.T) {
 		assert.NotNil(mnt, "Partition table '%s': failed to find root mountable", name)
 	}
 }
+
+func TestCreatePartitionTableLVMify(t *testing.T) {
+	assert := assert.New(t)
+	// math/rand is good enough in this case
+	/* #nosec G404 */
+	rng := rand.New(rand.NewSource(13))
+	for name := range testPartitionTables {
+		pt := testPartitionTables[name]
+
+		if name == "btrfs" || name == "luks" {
+			assert.Panics(func() {
+				_, _ = NewPartitionTable(&pt, bp, uint64(13*1024*1024), true, rng)
+			})
+			continue
+		}
+
+		mpt, err := NewPartitionTable(&pt, bp, uint64(13*1024*1024), true, rng)
+		assert.NoError(err, "Partition table generation failed: %s (%s)", name, err)
+
+		rootPath := entityPath(mpt, "/")
+		if rootPath == nil {
+			panic("no root mountpoint for PartitionTable")
+		}
+
+		parent := rootPath[1]
+		_, ok := parent.(*LVMLogicalVolume)
+		assert.True(ok, "Partition table '%s': root's parent (%q) is not an LVM logical volume", name, parent)
+	}
+
+}

internal/disk/partition_table.go

@@ -18,13 +18,16 @@ type PartitionTable struct {
 	ExtraPadding uint64 // Extra space at the end of the partition table (sectors)
 }
 
-func NewPartitionTable(basePT *PartitionTable, mountpoints []blueprint.FilesystemCustomization, imageSize uint64, rng *rand.Rand) (*PartitionTable, error) {
+func NewPartitionTable(basePT *PartitionTable, mountpoints []blueprint.FilesystemCustomization, imageSize uint64, lvmify bool, rng *rand.Rand) (*PartitionTable, error) {
 	newPT := basePT.Clone().(*PartitionTable)
 	for _, mnt := range mountpoints {
 		size := newPT.AlignUp(clampFSSize(mnt.Mountpoint, mnt.MinSize))
 		if path := entityPath(newPT, mnt.Mountpoint); len(path) != 0 {
 			resizeEntityBranch(path, size)
 		} else {
+			if lvmify {
+				newPT.ensureLVM()
+			}
 			if err := newPT.createFilesystem(mnt.Mountpoint, size); err != nil {
 				return nil, err
 			}
@@ -484,3 +487,45 @@ func (pt *PartitionTable) GenUUID(rng *rand.Rand) {
 		pt.UUID = uuid.Must(newRandomUUIDFromReader(rng)).String()
 	}
 }
+
+// ensureLVM will ensure that the root partition is on an LVM volume, i.e. if
+// it currently is not, it will wrap it in one
+func (pt *PartitionTable) ensureLVM() {
+
+	rootPath := entityPath(pt, "/")
+	if rootPath == nil {
+		panic("no root mountpoint for PartitionTable")
+	}
+
+	parent := rootPath[1] // NB: entityPath has reversed order
+
+	if _, ok := parent.(*LVMLogicalVolume); ok {
+		return
+	} else if part, ok := parent.(*Partition); ok {
+		filesystem := part.Payload
+
+		part.Payload = &LVMVolumeGroup{
+			Name:        "rootvg",
+			Description: "created via lvm2 and osbuild",
+			LogicalVolumes: []LVMLogicalVolume{
+				{
+					Size:    part.Size,
+					Name:    "rootlv",
+					Payload: filesystem,
+				},
+			},
+		}
+
+		// reset it so it will be grown later
+		part.Size = 0
+
+		if pt.Type == "gpt" {
+			part.Type = LVMPartitionGUID
+		} else {
+			part.Type = "8e"
+		}
+
+	} else {
+		panic("unsupported parent for LVM")
+	}
+}

internal/distro/rhel85/distro.go

@@ -324,7 +324,7 @@ func (t *imageType) getPartitionTable(
 
 	imageSize := t.Size(options.Size)
 
-	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, rng)
+	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, false, rng)
 }
 
 func (t *imageType) PartitionType() string {

internal/distro/rhel86/distro.go

@@ -394,7 +394,7 @@ func (t *imageType) getPartitionTable(
 
 	imageSize := t.Size(options.Size)
 
-	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, rng)
+	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, false, rng)
 }
 
 func (t *imageType) getDefaultImageConfig() *distro.ImageConfig {

internal/distro/rhel90/distro.go

@@ -382,7 +382,7 @@ func (t *imageType) getPartitionTable(
 
 	imageSize := t.Size(options.Size)
 
-	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, rng)
+	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, false, rng)
 }
 
 func (t *imageType) getDefaultImageConfig() *distro.ImageConfig {

internal/distro/rhel90beta/distro.go

@@ -359,7 +359,7 @@ func (t *imageType) getPartitionTable(
 
 	imageSize := t.Size(options.Size)
 
-	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, rng)
+	return disk.NewPartitionTable(&basePartitionTable, mountpoints, imageSize, false, rng)
 }
 
 func (t *imageType) PartitionType() string {

internal/osbuild2/device_test.go

@@ -18,7 +18,7 @@ func TestGenDeviceCreationStages(t *testing.T) {
 
 	luks_lvm := testPartitionTables["luks+lvm"]
 
-	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, rng)
+	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, false, rng)
 	assert.NoError(err)
 
 	stages := GenDeviceCreationStages(pt, "image.raw")
@@ -81,7 +81,7 @@ func TestGenDeviceFinishStages(t *testing.T) {
 
 	luks_lvm := testPartitionTables["luks+lvm"]
 
-	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, rng)
+	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, false, rng)
 	assert.NoError(err)
 
 	stages := GenDeviceFinishStages(pt, "image.raw")

internal/osbuild2/disk_test.go

@@ -18,7 +18,7 @@ func TestGenImageKernelOptions(t *testing.T) {
 
 	luks_lvm := testPartitionTables["luks+lvm"]
 
-	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, rng)
+	pt, err := disk.NewPartitionTable(&luks_lvm, []blueprint.FilesystemCustomization{}, 0, false, rng)
 	assert.NoError(err)
 
 	var uuid string