Merge branch 'lukeshu/api-cleanup'

19 files changed, 558 insertions, 457 deletions

diff --git a/cmd/btrfs-rec/inspect/dumptrees/print_tree.go b/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
index a8c2adf..60303e9 100644
--- a/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
+++ b/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
@@ -19,7 +19,6 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfssum"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
-	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
 	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
 	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
 )
@@ -54,7 +53,7 @@ func DumpTrees(ctx context.Context, out io.Writer, fs *btrfs.FS) {
 			dlog.Error(ctx, err)
 		},
 		btrfstree.TreeWalkHandler{
-			Item: func(_ btrfstree.TreePath, item btrfstree.Item) error {
+			Item: func(_ btrfstree.Path, item btrfstree.Item) error {
 				if item.Key.ItemType != btrfsitem.ROOT_ITEM_KEY {
 					return nil
 				}
@@ -100,12 +99,12 @@ var nodeHeaderSize = binstruct.StaticSize(btrfstree.NodeHeader{})
 func printTree(ctx context.Context, out io.Writer, fs *btrfs.FS, treeID btrfsprim.ObjID) {
 	var itemOffset uint32
 	handlers := btrfstree.TreeWalkHandler{
-		Node: func(path btrfstree.TreePath, nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) error {
-			printHeaderInfo(out, nodeRef.Data)
-			itemOffset = nodeRef.Data.Size - uint32(nodeHeaderSize)
+		Node: func(path btrfstree.Path, node *btrfstree.Node) error {
+			printHeaderInfo(out, node)
+			itemOffset = node.Size - uint32(nodeHeaderSize)
 			return nil
 		},
-		PreKeyPointer: func(path btrfstree.TreePath, item btrfstree.KeyPointer) error {
+		PreKeyPointer: func(path btrfstree.Path, item btrfstree.KeyPointer) error {
 			treeID := path[0].FromTree
 			textui.Fprintf(out, "\tkey %v block %v gen %v\n",
 				item.Key.Format(treeID),
@@ -113,7 +112,7 @@ func printTree(ctx context.Context, out io.Writer, fs *btrfs.FS, treeID btrfspri
 				item.Generation)
 			return nil
 		},
-		Item: func(path btrfstree.TreePath, item btrfstree.Item) error {
+		Item: func(path btrfstree.Path, item btrfstree.Item) error {
 			treeID := path[0].FromTree
 			i := path.Node(-1).FromItemSlot
 			bs, _ := binstruct.Marshal(item.Body)
@@ -375,7 +374,7 @@ func printTree(ctx context.Context, out io.Writer, fs *btrfs.FS, treeID btrfspri
 }
 
 // printHeaderInfo mimics btrfs-progs kernel-shared/print-tree.c:print_header_info()
-func printHeaderInfo(out io.Writer, node btrfstree.Node) {
+func printHeaderInfo(out io.Writer, node *btrfstree.Node) {
 	var typename string
 	if node.Head.Level > 0 { // interior node
 		typename = "node"
diff --git a/cmd/btrfs-rec/inspect/lsfiles/lsfiles.go b/cmd/btrfs-rec/inspect/lsfiles/lsfiles.go
new file mode 100644
index 0000000..a713b8a
--- /dev/null
+++ b/cmd/btrfs-rec/inspect/lsfiles/lsfiles.go
@@ -0,0 +1,249 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+// Package lsfiles is the guts of the `btrfs-rec inspect ls-files`
+// command, which prints a tree-listing of all files in the
+// filesystem.
+package lsfiles
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"path"
+	"strings"
+
+	"github.com/datawire/dlib/derror"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
+)
+
+func LsFiles(
+	out io.Writer,
+	fs interface {
+		btrfstree.TreeOperator
+		Superblock() (*btrfstree.Superblock, error)
+		diskio.ReaderAt[btrfsvol.LogicalAddr]
+	},
+) (err error) {
+	defer func() {
+		if _err := derror.PanicToError(recover()); _err != nil {
+			textui.Fprintf(out, "\n\n%+v\n", _err)
+			err = _err
+		}
+	}()
+
+	printSubvol(out, "", true, "/", btrfs.NewSubvolume(
+		fs,
+		btrfsprim.FS_TREE_OBJECTID,
+		false,
+	))
+
+	return nil
+}
+
+const (
+	tS = "    "
+	tl = "│   "
+	tT = "├── "
+	tL = "└── "
+)
+
+func printText(out io.Writer, prefix string, isLast bool, name, text string) {
+	first, rest := tT, tl
+	if isLast {
+		first, rest = tL, tS
+	}
+	for i, line := range strings.Split(textui.Sprintf("%q %s", name, text), "\n") {
+		_, _ = io.WriteString(out, prefix)
+		if i == 0 {
+			_, _ = io.WriteString(out, first)
+		} else {
+			_, _ = io.WriteString(out, rest)
+		}
+		_, _ = io.WriteString(out, line)
+		_, _ = io.WriteString(out, "\n")
+	}
+}
+
+func printSubvol(out io.Writer, prefix string, isLast bool, name string, subvol *btrfs.Subvolume) {
+	rootInode, err := subvol.GetRootInode()
+	if err != nil {
+		printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v err=%v",
+			subvol.TreeID, fmtErr(err)))
+		return
+	}
+	dir, err := subvol.LoadDir(rootInode)
+	if err != nil {
+		printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v err=%v",
+			subvol.TreeID, fmtErr(err)))
+		return
+	}
+	if name == "/" {
+		printDir(out, prefix, isLast, name, dir)
+		return
+	}
+	printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v", subvol.TreeID))
+	if isLast {
+		prefix += tS
+	} else {
+		prefix += tl
+	}
+	printDir(out, prefix, true, name, dir)
+}
+
+func fmtErr(err error) string {
+	errStr := err.Error()
+	if strings.Contains(errStr, "\n") {
+		errStr = "\\\n" + errStr
+	}
+	return errStr
+}
+
+func fmtInode(inode btrfs.BareInode) string {
+	var mode btrfsitem.StatMode
+	if inode.InodeItem == nil {
+		inode.Errs = append(inode.Errs, errors.New("missing INODE_ITEM"))
+	} else {
+		mode = inode.InodeItem.Mode
+	}
+	ret := textui.Sprintf("ino=%v mode=%v", inode.Inode, mode)
+	if len(inode.Errs) > 0 {
+		ret += " err=" + fmtErr(inode.Errs)
+	}
+	return ret
+}
+
+func printDir(out io.Writer, prefix string, isLast bool, name string, dir *btrfs.Dir) {
+	printText(out, prefix, isLast, name+"/", fmtInode(dir.BareInode))
+	if isLast {
+		prefix += tS
+	} else {
+		prefix += tl
+	}
+	for i, childName := range maps.SortedKeys(dir.ChildrenByName) {
+		printDirEntry(
+			out,
+			prefix,
+			i == len(dir.ChildrenByName)-1,
+			dir.SV,
+			path.Join(name, childName),
+			dir.ChildrenByName[childName])
+	}
+}
+
+func printDirEntry(out io.Writer, prefix string, isLast bool, subvol *btrfs.Subvolume, name string, entry btrfsitem.DirEntry) {
+	if len(entry.Data) != 0 {
+		panic(fmt.Errorf("TODO: I don't know how to handle dirent.data: %q", name))
+	}
+	switch entry.Type {
+	case btrfsitem.FT_DIR:
+		switch entry.Location.ItemType {
+		case btrfsitem.INODE_ITEM_KEY:
+			dir, err := subvol.LoadDir(entry.Location.ObjectID)
+			if err != nil {
+				printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
+				return
+			}
+			printDir(out, prefix, isLast, name, dir)
+		case btrfsitem.ROOT_ITEM_KEY:
+			printSubvol(out, prefix, isLast, name, subvol.NewChildSubvolume(entry.Location.ObjectID))
+		default:
+			panic(fmt.Errorf("TODO: I don't know how to handle an FT_DIR with location.ItemType=%v: %q",
+				entry.Location.ItemType, name))
+		}
+	case btrfsitem.FT_SYMLINK:
+		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
+			panic(fmt.Errorf("TODO: I don't know how to handle an FT_SYMLINK with location.ItemType=%v: %q",
+				entry.Location.ItemType, name))
+		}
+		file, err := subvol.LoadFile(entry.Location.ObjectID)
+		if err != nil {
+			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
+			return
+		}
+		printSymlink(out, prefix, isLast, name, file)
+	case btrfsitem.FT_REG_FILE:
+		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
+			panic(fmt.Errorf("TODO: I don't know how to handle an FT_REG_FILE with location.ItemType=%v: %q",
+				entry.Location.ItemType, name))
+		}
+		file, err := subvol.LoadFile(entry.Location.ObjectID)
+		if err != nil {
+			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
+			return
+		}
+		printFile(out, prefix, isLast, name, file)
+	case btrfsitem.FT_SOCK:
+		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
+			panic(fmt.Errorf("TODO: I don't know how to handle an FT_SOCK with location.ItemType=%v: %q",
+				entry.Location.ItemType, name))
+		}
+		file, err := subvol.LoadFile(entry.Location.ObjectID)
+		if err != nil {
+			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
+			return
+		}
+		printSocket(out, prefix, isLast, name, file)
+	case btrfsitem.FT_FIFO:
+		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
+			panic(fmt.Errorf("TODO: I don't know how to handle an FT_FIFO with location.ItemType=%v: %q",
+				entry.Location.ItemType, name))
+		}
+		file, err := subvol.LoadFile(entry.Location.ObjectID)
+		if err != nil {
+			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
+			return
+		}
+		printPipe(out, prefix, isLast, name, file)
+	default:
+		panic(fmt.Errorf("TODO: I don't know how to handle a fileType=%v: %q",
+			entry.Type, name))
+	}
+}
+
+func printSymlink(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
+	var tgt []byte
+	if file.InodeItem != nil {
+		var err error
+		tgt, err = io.ReadAll(io.NewSectionReader(file, 0, file.InodeItem.Size))
+		if err != nil {
+			file.Errs = append(file.Errs, err)
+		}
+	}
+	printText(out, prefix, isLast, name, textui.Sprintf(
+		"-> %q : %s",
+		tgt,
+		fmtInode(file.BareInode)))
+}
+
+func printFile(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
+	if file.InodeItem != nil {
+		if _, err := io.Copy(io.Discard, io.NewSectionReader(file, 0, file.InodeItem.Size)); err != nil {
+			file.Errs = append(file.Errs, err)
+		}
+	}
+	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
+}
+
+func printSocket(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
+	if file.InodeItem != nil && file.InodeItem.Size > 0 {
+		panic(fmt.Errorf("TODO: I don't know how to handle a socket with size>0: %q", name))
+	}
+	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
+}
+
+func printPipe(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
+	if file.InodeItem != nil && file.InodeItem.Size > 0 {
+		panic(fmt.Errorf("TODO: I don't know how to handle a pipe with size>0: %q", name))
+	}
+	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
+}
diff --git a/cmd/btrfs-rec/inspect/mount/mount.go b/cmd/btrfs-rec/inspect/mount/mount.go
index 0e8faf1..4049393 100644
--- a/cmd/btrfs-rec/inspect/mount/mount.go
+++ b/cmd/btrfs-rec/inspect/mount/mount.go
@@ -28,6 +28,7 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsutil"
 	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
 	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
@@ -45,14 +46,21 @@ func MountRO(ctx context.Context, fs *btrfs.FS, mountpoint string, noChecksums b
 		deviceName = abs
 	}
 
+	sb, err := fs.Superblock()
+	if err != nil {
+		return err
+	}
+
 	rootSubvol := &subvolume{
-		Subvolume: btrfs.Subvolume{
-			FS:          btrfsutil.NewOldRebuiltForrest(ctx, fs),
-			TreeID:      btrfsprim.FS_TREE_OBJECTID,
-			NoChecksums: noChecksums,
-		},
+		Subvolume: btrfs.NewSubvolume(
+			btrfsutil.NewOldRebuiltForrest(ctx, fs),
+			btrfsprim.FS_TREE_OBJECTID,
+			noChecksums,
+		),
 		DeviceName: deviceName,
 		Mountpoint: mountpoint,
+
+		sb: sb,
 	}
 	return rootSubvol.Run(ctx)
 }
@@ -107,10 +115,12 @@ type fileState struct {
 }
 
 type subvolume struct {
-	btrfs.Subvolume
+	*btrfs.Subvolume
 	DeviceName string
 	Mountpoint string
 
+	sb *btrfstree.Superblock
+
 	fuseutil.NotImplementedFileSystem
 	lastHandle  uint64
 	dirHandles  typedsync.Map[fuseops.HandleID, *dirState]
@@ -189,11 +199,8 @@ func (sv *subvolume) LoadDir(inode btrfsprim.ObjID) (val *btrfs.Dir, err error)
 					workerName := fmt.Sprintf("%d-%s", val.Inode, filepath.Base(subMountpoint))
 					sv.grp.Go(workerName, func(ctx context.Context) error {
 						subSv := &subvolume{
-							Subvolume: btrfs.Subvolume{
-								FS:          sv.FS,
-								TreeID:      entry.Location.ObjectID,
-								NoChecksums: sv.NoChecksums,
-							},
+							sb:         sv.sb,
+							Subvolume:  sv.NewChildSubvolume(entry.Location.ObjectID),
 							DeviceName: sv.DeviceName,
 							Mountpoint: filepath.Join(sv.Mountpoint, subMountpoint[1:]),
 						}
@@ -208,11 +215,9 @@ func (sv *subvolume) LoadDir(inode btrfsprim.ObjID) (val *btrfs.Dir, err error)
 }
 
 func (sv *subvolume) StatFS(_ context.Context, op *fuseops.StatFSOp) error {
+	sb := sv.sb
+
 	// See linux.git/fs/btrfs/super.c:btrfs_statfs()
-	sb, err := sv.FS.Superblock()
-	if err != nil {
-		return err
-	}
 
 	op.IoSize = sb.SectorSize
 	op.BlockSize = sb.SectorSize
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process.go b/cmd/btrfs-rec/inspect/rebuildmappings/process.go
index a93b697..7a49cc6 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process.go
@@ -117,7 +117,7 @@ func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesR
 	// First dedup them, because they change for allocations and
 	// CoW means that they'll bounce around a lot, so you likely
 	// have oodles of duplicates?
-	bgs, err := DedupBlockGroups(scanResults)
+	bgs, err := dedupedBlockGroups(scanResults)
 	if err != nil {
 		return err
 	}
@@ -137,10 +137,7 @@ func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesR
 			PAddr:      otherPAddr.Add(-offsetWithinChunk),
 			Size:       bg.Size,
 			SizeLocked: true,
-			Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
-				OK:  true,
-				Val: bg.Flags,
-			},
+			Flags:      containers.OptionalValue(bg.Flags),
 		}
 		if err := fs.LV.AddMapping(mapping); err != nil {
 			dlog.Errorf(ctx, "error: adding flags from blockgroup: %v", err)
@@ -162,8 +159,8 @@ func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesR
 	// slower.
 	ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "5/6")
 	dlog.Infof(_ctx, "5/6: Searching for %d block groups in checksum map (exact)...", len(bgs))
-	physicalSums := ExtractPhysicalSums(scanResults)
-	logicalSums := ExtractLogicalSums(ctx, scanResults)
+	physicalSums := extractPhysicalSums(scanResults)
+	logicalSums := extractLogicalSums(ctx, scanResults)
 	if err := matchBlockGroupSumsExact(ctx, fs, bgs, physicalSums, logicalSums); err != nil {
 		return err
 	}
@@ -179,7 +176,7 @@ func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesR
 	ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "report")
 	dlog.Info(_ctx, "report:")
 
-	unmappedPhysicalRegions := ListUnmappedPhysicalRegions(fs)
+	unmappedPhysicalRegions := listUnmappedPhysicalRegions(fs)
 	var unmappedPhysical btrfsvol.AddrDelta
 	var numUnmappedPhysical int
 	for _, devRegions := range unmappedPhysicalRegions {
@@ -190,7 +187,7 @@ func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesR
 	}
 	dlog.Infof(ctx, "... %d of unmapped physical space (across %d regions)", textui.IEC(unmappedPhysical, "B"), numUnmappedPhysical)
 
-	unmappedLogicalRegions := ListUnmappedLogicalRegions(fs, logicalSums)
+	unmappedLogicalRegions := listUnmappedLogicalRegions(fs, logicalSums)
 	var unmappedLogical btrfsvol.AddrDelta
 	for _, region := range unmappedLogicalRegions {
 		unmappedLogical += region.Size()
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_blockgroups.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_blockgroups.go
index f8d2337..e7cdf0e 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process_blockgroups.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_blockgroups.go
@@ -13,18 +13,18 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
 )
 
-type BlockGroup struct {
+type blockGroup struct {
 	LAddr btrfsvol.LogicalAddr
 	Size  btrfsvol.AddrDelta
 	Flags btrfsvol.BlockGroupFlags
 }
 
-func DedupBlockGroups(scanResults ScanDevicesResult) (map[btrfsvol.LogicalAddr]BlockGroup, error) {
+func dedupedBlockGroups(scanResults ScanDevicesResult) (map[btrfsvol.LogicalAddr]blockGroup, error) {
 	// Dedup
-	bgsSet := make(containers.Set[BlockGroup])
+	bgsSet := make(containers.Set[blockGroup])
 	for _, devResults := range scanResults {
 		for _, bg := range devResults.FoundBlockGroups {
-			bgsSet.Insert(BlockGroup{
+			bgsSet.Insert(blockGroup{
 				LAddr: btrfsvol.LogicalAddr(bg.Key.ObjectID),
 				Size:  btrfsvol.AddrDelta(bg.Key.Offset),
 				Flags: bg.BG.Flags,
@@ -49,7 +49,7 @@ func DedupBlockGroups(scanResults ScanDevicesResult) (map[btrfsvol.LogicalAddr]B
 
 	// Return.  We return a map instead of a slice in order to
 	// facilitate easy deletes.
-	bgsMap := make(map[btrfsvol.LogicalAddr]BlockGroup, len(bgsSet))
+	bgsMap := make(map[btrfsvol.LogicalAddr]blockGroup, len(bgsSet))
 	for bg := range bgsSet {
 		bgsMap[bg.LAddr] = bg
 	}
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go
index 533ae67..5148e5c 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go
@@ -19,15 +19,15 @@ import (
 
 func matchBlockGroupSumsExact(ctx context.Context,
 	fs *btrfs.FS,
-	blockgroups map[btrfsvol.LogicalAddr]BlockGroup,
+	blockgroups map[btrfsvol.LogicalAddr]blockGroup,
 	physicalSums map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr],
-	logicalSums SumRunWithGaps[btrfsvol.LogicalAddr],
+	logicalSums sumRunWithGaps[btrfsvol.LogicalAddr],
 ) error {
-	regions := ListUnmappedPhysicalRegions(fs)
+	regions := listUnmappedPhysicalRegions(fs)
 	numBlockgroups := len(blockgroups)
 	for i, bgLAddr := range maps.SortedKeys(blockgroups) {
 		blockgroup := blockgroups[bgLAddr]
-		bgRun := SumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
+		bgRun := sumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
 		if len(bgRun.Runs) == 0 {
 			dlog.Errorf(ctx, "(%v/%v) blockgroup[laddr=%v] can't be matched because it has 0 runs",
 				i+1, numBlockgroups, bgLAddr)
@@ -35,7 +35,7 @@ func matchBlockGroupSumsExact(ctx context.Context,
 		}
 
 		var matches []btrfsvol.QualifiedPhysicalAddr
-		if err := WalkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
+		if err := walkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
 			rawMatches := indexAll[int, btrfssum.ShortSum](region, bgRun)
 			for _, match := range rawMatches {
 				matches = append(matches, btrfsvol.QualifiedPhysicalAddr{
@@ -63,10 +63,7 @@ func matchBlockGroupSumsExact(ctx context.Context,
 			PAddr:      matches[0],
 			Size:       blockgroup.Size,
 			SizeLocked: true,
-			Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
-				OK:  true,
-				Val: blockgroup.Flags,
-			},
+			Flags:      containers.OptionalValue(blockgroup.Flags),
 		}
 		if err := fs.LV.AddMapping(mapping); err != nil {
 			dlog.Errorf(ctx, "error: %v", err)
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_fuzzy.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_fuzzy.go
index 00f367f..f3557cd 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_fuzzy.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_fuzzy.go
@@ -39,17 +39,17 @@ func (a fuzzyRecord) Compare(b fuzzyRecord) int {
 
 func matchBlockGroupSumsFuzzy(ctx context.Context,
 	fs *btrfs.FS,
-	blockgroups map[btrfsvol.LogicalAddr]BlockGroup,
+	blockgroups map[btrfsvol.LogicalAddr]blockGroup,
 	physicalSums map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr],
-	logicalSums SumRunWithGaps[btrfsvol.LogicalAddr],
+	logicalSums sumRunWithGaps[btrfsvol.LogicalAddr],
 ) error {
 	_ctx := ctx
 
 	ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.substep", "indexing")
 	dlog.Info(ctx, "Indexing physical regions...") // O(m)
-	regions := ListUnmappedPhysicalRegions(fs)
+	regions := listUnmappedPhysicalRegions(fs)
 	physicalIndex := make(map[btrfssum.ShortSum][]btrfsvol.QualifiedPhysicalAddr)
-	if err := WalkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
+	if err := walkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
 		return region.Walk(ctx, func(paddr btrfsvol.PhysicalAddr, sum btrfssum.ShortSum) error {
 			physicalIndex[sum] = append(physicalIndex[sum], btrfsvol.QualifiedPhysicalAddr{
 				Dev:  devID,
@@ -67,7 +67,7 @@ func matchBlockGroupSumsFuzzy(ctx context.Context,
 	numBlockgroups := len(blockgroups)
 	for i, bgLAddr := range maps.SortedKeys(blockgroups) {
 		blockgroup := blockgroups[bgLAddr]
-		bgRun := SumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
+		bgRun := sumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
 
 		d := bgRun.PatLen()
 		matches := make(map[btrfsvol.QualifiedPhysicalAddr]int)
@@ -123,10 +123,7 @@ func matchBlockGroupSumsFuzzy(ctx context.Context,
 			PAddr:      best.Dat[0].PAddr,
 			Size:       blockgroup.Size,
 			SizeLocked: true,
-			Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
-				OK:  true,
-				Val: blockgroup.Flags,
-			},
+			Flags:      containers.OptionalValue(blockgroup.Flags),
 		}
 		if err := fs.LV.AddMapping(mapping); err != nil {
 			dlog.Errorf(ctx, "error: %v", err)
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_logical.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_logical.go
index 2cdabb7..52f8252 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_logical.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_logical.go
@@ -19,8 +19,8 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
 )
 
-func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumRunWithGaps[btrfsvol.LogicalAddr] {
-	var records []SysExtentCSum
+func extractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) sumRunWithGaps[btrfsvol.LogicalAddr] {
+	var records []FoundExtentCSum
 	for _, devResults := range scanResults {
 		records = append(records, devResults.FoundExtentCSums...)
 	}
@@ -37,7 +37,7 @@ func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumR
 		}
 	})
 	if len(records) == 0 {
-		return SumRunWithGaps[btrfsvol.LogicalAddr]{}
+		return sumRunWithGaps[btrfsvol.LogicalAddr]{}
 	}
 	sumSize := records[0].Sums.ChecksumSize
 
@@ -52,10 +52,10 @@ func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumR
 	// "AAAAAAA" shouldn't be present, and if we just discard "BBBBBBBB"
 	// because it conflicts with "CCCCCCC", then we would erroneously
 	// include "AAAAAAA".
-	addrspace := new(containers.RBTree[SysExtentCSum])
+	addrspace := new(containers.RBTree[FoundExtentCSum])
 	for _, newRecord := range records {
 		for {
-			conflict := addrspace.Search(func(oldRecord SysExtentCSum) int {
+			conflict := addrspace.Search(func(oldRecord FoundExtentCSum) int {
 				switch {
 				case newRecord.Sums.Addr.Add(newRecord.Sums.Size()) <= oldRecord.Sums.Addr:
 					// 'newRecord' is wholly to the left of 'oldRecord'.
@@ -127,7 +127,7 @@ func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumR
 			case newRecord.Sums.Addr.Add(newRecord.Sums.Size()) > overlapEnd:
 				suffix = newRecord.Sums.Sums[newOverlapEnd:]
 			}
-			unionRecord := SysExtentCSum{
+			unionRecord := FoundExtentCSum{
 				Generation: oldRecord.Generation,
 				Sums: btrfsitem.ExtentCSum{
 					SumRun: btrfssum.SumRun[btrfsvol.LogicalAddr]{
@@ -143,11 +143,11 @@ func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumR
 		}
 	}
 
-	// Now flatten that RBTree in to a SumRunWithGaps.
-	var flattened SumRunWithGaps[btrfsvol.LogicalAddr]
+	// Now flatten that RBTree in to a sumRunWithGaps.
+	var flattened sumRunWithGaps[btrfsvol.LogicalAddr]
 	var curAddr btrfsvol.LogicalAddr
 	var curSums strings.Builder
-	addrspace.Range(func(node *containers.RBNode[SysExtentCSum]) bool {
+	addrspace.Range(func(node *containers.RBNode[FoundExtentCSum]) bool {
 		curEnd := curAddr + (btrfsvol.LogicalAddr(curSums.Len()/sumSize) * btrfssum.BlockSize)
 		if node.Value.Sums.Addr != curEnd {
 			if curSums.Len() > 0 {
@@ -178,7 +178,7 @@ func ExtractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) SumR
 	return flattened
 }
 
-func ListUnmappedLogicalRegions(fs *btrfs.FS, logicalSums SumRunWithGaps[btrfsvol.LogicalAddr]) []btrfssum.SumRun[btrfsvol.LogicalAddr] {
+func listUnmappedLogicalRegions(fs *btrfs.FS, logicalSums sumRunWithGaps[btrfsvol.LogicalAddr]) []btrfssum.SumRun[btrfsvol.LogicalAddr] {
 	// There are a lot of ways this algorithm could be made
 	// faster.
 	var ret []btrfssum.SumRun[btrfsvol.LogicalAddr]
@@ -221,8 +221,8 @@ func ListUnmappedLogicalRegions(fs *btrfs.FS, logicalSums SumRunWithGaps[btrfsvo
 	return ret
 }
 
-func SumsForLogicalRegion(sums SumRunWithGaps[btrfsvol.LogicalAddr], beg btrfsvol.LogicalAddr, size btrfsvol.AddrDelta) SumRunWithGaps[btrfsvol.LogicalAddr] {
-	runs := SumRunWithGaps[btrfsvol.LogicalAddr]{
+func sumsForLogicalRegion(sums sumRunWithGaps[btrfsvol.LogicalAddr], beg btrfsvol.LogicalAddr, size btrfsvol.AddrDelta) sumRunWithGaps[btrfsvol.LogicalAddr] {
+	runs := sumRunWithGaps[btrfsvol.LogicalAddr]{
 		Addr: beg,
 		Size: size,
 	}
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_physical.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_physical.go
index 392ded9..5f8d932 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_physical.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_sums_physical.go
@@ -16,7 +16,7 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
 )
 
-func ExtractPhysicalSums(scanResults ScanDevicesResult) map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr] {
+func extractPhysicalSums(scanResults ScanDevicesResult) map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr] {
 	ret := make(map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr], len(scanResults))
 	for devID, devResults := range scanResults {
 		ret[devID] = devResults.Checksums
@@ -24,12 +24,12 @@ func ExtractPhysicalSums(scanResults ScanDevicesResult) map[btrfsvol.DeviceID]bt
 	return ret
 }
 
-type PhysicalRegion struct {
+type physicalRegion struct {
 	Beg, End btrfsvol.PhysicalAddr
 }
 
-func ListUnmappedPhysicalRegions(fs *btrfs.FS) map[btrfsvol.DeviceID][]PhysicalRegion {
-	regions := make(map[btrfsvol.DeviceID][]PhysicalRegion)
+func listUnmappedPhysicalRegions(fs *btrfs.FS) map[btrfsvol.DeviceID][]physicalRegion {
+	regions := make(map[btrfsvol.DeviceID][]physicalRegion)
 	pos := make(map[btrfsvol.DeviceID]btrfsvol.PhysicalAddr)
 	mappings := fs.LV.Mappings()
 	sort.Slice(mappings, func(i, j int) bool {
@@ -37,7 +37,7 @@ func ListUnmappedPhysicalRegions(fs *btrfs.FS) map[btrfsvol.DeviceID][]PhysicalR
 	})
 	for _, mapping := range mappings {
 		if pos[mapping.PAddr.Dev] < mapping.PAddr.Addr {
-			regions[mapping.PAddr.Dev] = append(regions[mapping.PAddr.Dev], PhysicalRegion{
+			regions[mapping.PAddr.Dev] = append(regions[mapping.PAddr.Dev], physicalRegion{
 				Beg: pos[mapping.PAddr.Dev],
 				End: mapping.PAddr.Addr,
 			})
@@ -49,7 +49,7 @@ func ListUnmappedPhysicalRegions(fs *btrfs.FS) map[btrfsvol.DeviceID][]PhysicalR
 	for devID, dev := range fs.LV.PhysicalVolumes() {
 		devSize := dev.Size()
 		if pos[devID] < devSize {
-			regions[devID] = append(regions[devID], PhysicalRegion{
+			regions[devID] = append(regions[devID], physicalRegion{
 				Beg: pos[devID],
 				End: devSize,
 			})
@@ -62,9 +62,9 @@ func roundUp[T constraints.Integer](x, multiple T) T {
 	return ((x + multiple - 1) / multiple) * multiple
 }
 
-func WalkUnmappedPhysicalRegions(ctx context.Context,
+func walkUnmappedPhysicalRegions(ctx context.Context,
 	physicalSums map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr],
-	gaps map[btrfsvol.DeviceID][]PhysicalRegion,
+	gaps map[btrfsvol.DeviceID][]physicalRegion,
 	fn func(btrfsvol.DeviceID, btrfssum.SumRun[btrfsvol.PhysicalAddr]) error,
 ) error {
 	for _, devID := range maps.SortedKeys(gaps) {
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/scan.go b/cmd/btrfs-rec/inspect/rebuildmappings/scan.go
index b88f01c..76d8a75 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/scan.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/scan.go
@@ -19,7 +19,6 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsutil"
 	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
-	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
 	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
 )
 
@@ -30,29 +29,31 @@ type ScanDevicesResult = map[btrfsvol.DeviceID]ScanOneDeviceResult
 type ScanOneDeviceResult struct {
 	Checksums        btrfssum.SumRun[btrfsvol.PhysicalAddr]
 	FoundNodes       map[btrfsvol.LogicalAddr][]btrfsvol.PhysicalAddr
-	FoundChunks      []btrfstree.SysChunk
-	FoundBlockGroups []SysBlockGroup
-	FoundDevExtents  []SysDevExtent
-	FoundExtentCSums []SysExtentCSum
+	FoundChunks      []FoundChunk
+	FoundBlockGroups []FoundBlockGroup
+	FoundDevExtents  []FoundDevExtent
+	FoundExtentCSums []FoundExtentCSum
 }
 
-type SysBlockGroup struct {
+type FoundChunk = btrfstree.SysChunk
+
+type FoundBlockGroup struct {
 	Key btrfsprim.Key
 	BG  btrfsitem.BlockGroup
 }
 
-type SysDevExtent struct {
+type FoundDevExtent struct {
 	Key    btrfsprim.Key
 	DevExt btrfsitem.DevExtent
 }
 
-type SysExtentCSum struct {
+type FoundExtentCSum struct {
 	Generation btrfsprim.Generation
 	Sums       btrfsitem.ExtentCSum
 }
 
 // Compare implements containers.Ordered.
-func (a SysExtentCSum) Compare(b SysExtentCSum) int {
+func (a FoundExtentCSum) Compare(b FoundExtentCSum) int {
 	return containers.NativeCompare(a.Sums.Addr, b.Sums.Addr)
 }
 
@@ -121,22 +122,22 @@ func (scanner *deviceScanner) ScanSector(_ context.Context, dev *btrfs.Device, p
 	return nil
 }
 
-func (scanner *deviceScanner) ScanNode(ctx context.Context, nodeRef *diskio.Ref[btrfsvol.PhysicalAddr, btrfstree.Node]) error {
-	scanner.result.FoundNodes[nodeRef.Data.Head.Addr] = append(scanner.result.FoundNodes[nodeRef.Data.Head.Addr], nodeRef.Addr)
-	for i, item := range nodeRef.Data.BodyLeaf {
+func (scanner *deviceScanner) ScanNode(ctx context.Context, addr btrfsvol.PhysicalAddr, node *btrfstree.Node) error {
+	scanner.result.FoundNodes[node.Head.Addr] = append(scanner.result.FoundNodes[node.Head.Addr], addr)
+	for i, item := range node.BodyLeaf {
 		switch item.Key.ItemType {
 		case btrfsitem.CHUNK_ITEM_KEY:
 			switch itemBody := item.Body.(type) {
 			case *btrfsitem.Chunk:
 				dlog.Tracef(ctx, "node@%v: item %v: found chunk",
-					nodeRef.Addr, i)
-				scanner.result.FoundChunks = append(scanner.result.FoundChunks, btrfstree.SysChunk{
+					addr, i)
+				scanner.result.FoundChunks = append(scanner.result.FoundChunks, FoundChunk{
 					Key:   item.Key,
 					Chunk: *itemBody,
 				})
 			case *btrfsitem.Error:
 				dlog.Errorf(ctx, "node@%v: item %v: error: malformed CHUNK_ITEM: %v",
-					nodeRef.Addr, i, itemBody.Err)
+					addr, i, itemBody.Err)
 			default:
 				panic(fmt.Errorf("should not happen: CHUNK_ITEM has unexpected item type: %T", itemBody))
 			}
@@ -144,14 +145,14 @@ func (scanner *deviceScanner) ScanNode(ctx context.Context, nodeRef *diskio.Ref[
 			switch itemBody := item.Body.(type) {
 			case *btrfsitem.BlockGroup:
 				dlog.Tracef(ctx, "node@%v: item %v: found block group",
-					nodeRef.Addr, i)
-				scanner.result.FoundBlockGroups = append(scanner.result.FoundBlockGroups, SysBlockGroup{
+					addr, i)
+				scanner.result.FoundBlockGroups = append(scanner.result.FoundBlockGroups, FoundBlockGroup{
 					Key: item.Key,
 					BG:  *itemBody,
 				})
 			case *btrfsitem.Error:
 				dlog.Errorf(ctx, "node@%v: item %v: error: malformed BLOCK_GROUP_ITEM: %v",
-					nodeRef.Addr, i, itemBody.Err)
+					addr, i, itemBody.Err)
 			default:
 				panic(fmt.Errorf("should not happen: BLOCK_GROUP_ITEM has unexpected item type: %T", itemBody))
 			}
@@ -159,14 +160,14 @@ func (scanner *deviceScanner) ScanNode(ctx context.Context, nodeRef *diskio.Ref[
 			switch itemBody := item.Body.(type) {
 			case *btrfsitem.DevExtent:
 				dlog.Tracef(ctx, "node@%v: item %v: found dev extent",
-					nodeRef.Addr, i)
-				scanner.result.FoundDevExtents = append(scanner.result.FoundDevExtents, SysDevExtent{
+					addr, i)
+				scanner.result.FoundDevExtents = append(scanner.result.FoundDevExtents, FoundDevExtent{
 					Key:    item.Key,
 					DevExt: *itemBody,
 				})
 			case *btrfsitem.Error:
 				dlog.Errorf(ctx, "node@%v: item %v: error: malformed DEV_EXTENT: %v",
-					nodeRef.Addr, i, itemBody.Err)
+					addr, i, itemBody.Err)
 			default:
 				panic(fmt.Errorf("should not happen: DEV_EXTENT has unexpected item type: %T", itemBody))
 			}
@@ -174,14 +175,14 @@ func (scanner *deviceScanner) ScanNode(ctx context.Context, nodeRef *diskio.Ref[
 			switch itemBody := item.Body.(type) {
 			case *btrfsitem.ExtentCSum:
 				dlog.Tracef(ctx, "node@%v: item %v: found csums",
-					nodeRef.Addr, i)
-				scanner.result.FoundExtentCSums = append(scanner.result.FoundExtentCSums, SysExtentCSum{
-					Generation: nodeRef.Data.Head.Generation,
+					addr, i)
+				scanner.result.FoundExtentCSums = append(scanner.result.FoundExtentCSums, FoundExtentCSum{
+					Generation: node.Head.Generation,
 					Sums:       *itemBody,
 				})
 			case *btrfsitem.Error:
 				dlog.Errorf(ctx, "node@%v: item %v: error: malformed is EXTENT_CSUM: %v",
-					nodeRef.Addr, i, itemBody.Err)
+					addr, i, itemBody.Err)
 			default:
 				panic(fmt.Errorf("should not happen: EXTENT_CSUM has unexpected item type: %T", itemBody))
 			}
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/sumrunwithgaps.go b/cmd/btrfs-rec/inspect/rebuildmappings/sumrunwithgaps.go
index f79e2be..3522b3e 100644
--- a/cmd/btrfs-rec/inspect/rebuildmappings/sumrunwithgaps.go
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/sumrunwithgaps.go
@@ -17,7 +17,7 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
 )
 
-type SumRunWithGaps[Addr btrfsvol.IntAddr[Addr]] struct {
+type sumRunWithGaps[Addr btrfsvol.IntAddr[Addr]] struct {
 	// Store the start address and size, in order to facilitate
 	// leading and trailing gaps.
 	Addr Addr
@@ -27,16 +27,16 @@ type SumRunWithGaps[Addr btrfsvol.IntAddr[Addr]] struct {
 }
 
 var (
-	_ lowmemjson.Encodable = SumRunWithGaps[btrfsvol.LogicalAddr]{}
-	_ lowmemjson.Decodable = (*SumRunWithGaps[btrfsvol.LogicalAddr])(nil)
+	_ lowmemjson.Encodable = sumRunWithGaps[btrfsvol.LogicalAddr]{}
+	_ lowmemjson.Decodable = (*sumRunWithGaps[btrfsvol.LogicalAddr])(nil)
 )
 
 // PatLen implements kmpPattern[int, ShortSum].
-func (sg SumRunWithGaps[Addr]) PatLen() int {
+func (sg sumRunWithGaps[Addr]) PatLen() int {
 	return int(sg.Size / btrfssum.BlockSize)
 }
 
-func (sg SumRunWithGaps[Addr]) PctFull() float64 {
+func (sg sumRunWithGaps[Addr]) PctFull() float64 {
 	total := sg.PatLen()
 	var full int
 	for _, run := range sg.Runs {
@@ -45,7 +45,7 @@ func (sg SumRunWithGaps[Addr]) PctFull() float64 {
 	return float64(full) / float64(total)
 }
 
-func (sg SumRunWithGaps[Addr]) RunForAddr(addr Addr) (btrfssum.SumRun[Addr], Addr, bool) {
+func (sg sumRunWithGaps[Addr]) RunForAddr(addr Addr) (btrfssum.SumRun[Addr], Addr, bool) {
 	for _, run := range sg.Runs {
 		if run.Addr > addr {
 			return btrfssum.SumRun[Addr]{}, run.Addr, false
@@ -58,7 +58,7 @@ func (sg SumRunWithGaps[Addr]) RunForAddr(addr Addr) (btrfssum.SumRun[Addr], Add
 	return btrfssum.SumRun[Addr]{}, math.MaxInt64, false
 }
 
-func (sg SumRunWithGaps[Addr]) SumForAddr(addr Addr) (btrfssum.ShortSum, bool) {
+func (sg sumRunWithGaps[Addr]) SumForAddr(addr Addr) (btrfssum.ShortSum, bool) {
 	if addr < sg.Addr || addr >= sg.Addr.Add(sg.Size) {
 		return "", false
 	}
@@ -80,7 +80,7 @@ func (sg SumRunWithGaps[Addr]) SumForAddr(addr Addr) (btrfssum.ShortSum, bool) {
 	return run.Sums[off : off+run.ChecksumSize], true
 }
 
-func (sg SumRunWithGaps[Addr]) Walk(ctx context.Context, fn func(Addr, btrfssum.ShortSum) error) error {
+func (sg sumRunWithGaps[Addr]) Walk(ctx context.Context, fn func(Addr, btrfssum.ShortSum) error) error {
 	for _, run := range sg.Runs {
 		if err := run.Walk(ctx, fn); err != nil {
 			return err
@@ -90,12 +90,12 @@ func (sg SumRunWithGaps[Addr]) Walk(ctx context.Context, fn func(Addr, btrfssum.
 }
 
 // PatGet implements kmpPattern[int, ShortSum].
-func (sg SumRunWithGaps[Addr]) PatGet(sumIdx int) (btrfssum.ShortSum, bool) {
+func (sg sumRunWithGaps[Addr]) PatGet(sumIdx int) (btrfssum.ShortSum, bool) {
 	addr := sg.Addr.Add(btrfsvol.AddrDelta(sumIdx) * btrfssum.BlockSize)
 	return sg.SumForAddr(addr)
 }
 
-func (sg SumRunWithGaps[Addr]) EncodeJSON(w io.Writer) error {
+func (sg sumRunWithGaps[Addr]) EncodeJSON(w io.Writer) error {
 	if _, err := fmt.Fprintf(w, `{"Addr":%d,"Size":%d,"Runs":[`, sg.Addr, sg.Size); err != nil {
 		return err
 	}
@@ -136,8 +136,8 @@ func (sg SumRunWithGaps[Addr]) EncodeJSON(w io.Writer) error {
 	return nil
 }
 
-func (sg *SumRunWithGaps[Addr]) DecodeJSON(r io.RuneScanner) error {
-	*sg = SumRunWithGaps[Addr]{}
+func (sg *sumRunWithGaps[Addr]) DecodeJSON(r io.RuneScanner) error {
+	*sg = sumRunWithGaps[Addr]{}
 	var name string
 	return lowmemjson.DecodeObject(r,
 		func(r io.RuneScanner) error {
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
index ca1ce8c..0d25ac3 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
@@ -47,9 +47,7 @@ func (o keyAndTree) String() string {
 }
 
 type rebuilder struct {
-	sb    btrfstree.Superblock
-	graph btrfsutil.Graph
-	keyIO *btrfsutil.KeyIO
+	scan ScanDevicesResult
 
 	rebuilt *btrfsutil.RebuiltForrest
 
@@ -67,9 +65,9 @@ type rebuilder struct {
 }
 
 type treeAugmentQueue struct {
-	zero   map[Want]struct{}
-	single map[Want]btrfsvol.LogicalAddr
-	multi  map[Want]containers.Set[btrfsvol.LogicalAddr]
+	zero   map[want]struct{}
+	single map[want]btrfsvol.LogicalAddr
+	multi  map[want]containers.Set[btrfsvol.LogicalAddr]
 }
 
 type Rebuilder interface {
@@ -79,22 +77,20 @@ type Rebuilder interface {
 
 func NewRebuilder(ctx context.Context, fs *btrfs.FS, nodeList []btrfsvol.LogicalAddr) (Rebuilder, error) {
 	ctx = dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.step", "read-fs-data")
-	sb, nodeGraph, keyIO, err := ScanDevices(ctx, fs, nodeList) // ScanDevices does its own logging
+	scanData, err := ScanDevices(ctx, fs, nodeList) // ScanDevices does its own logging
 	if err != nil {
 		return nil, err
 	}
 
 	o := &rebuilder{
-		sb:    sb,
-		graph: nodeGraph,
-		keyIO: keyIO,
+		scan: scanData,
 	}
-	o.rebuilt = btrfsutil.NewRebuiltForrest(sb, nodeGraph, keyIO, o)
+	o.rebuilt = btrfsutil.NewRebuiltForrest(fs, scanData.Superblock, scanData.Graph, forrestCallbacks{o})
 	return o, nil
 }
 
 func (o *rebuilder) ListRoots(ctx context.Context) map[btrfsprim.ObjID]containers.Set[btrfsvol.LogicalAddr] {
-	return o.rebuilt.ListRoots(ctx)
+	return o.rebuilt.RebuiltListRoots(ctx)
 }
 
 func (o *rebuilder) Rebuild(ctx context.Context) error {
@@ -163,7 +159,7 @@ func (o *rebuilder) processTreeQueue(ctx context.Context) error {
 		}
 		// This will call o.AddedItem as nescessary, which
 		// inserts to o.addedItemQueue.
-		_ = o.rebuilt.Tree(ctx, o.curKey.TreeID)
+		_ = o.rebuilt.RebuiltTree(ctx, o.curKey.TreeID)
 	}
 
 	return nil
@@ -201,18 +197,18 @@ func (o *rebuilder) processAddedItemQueue(ctx context.Context) error {
 		progressWriter.Set(progress)
 
 		ctx := dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.rebuild.settle.item", key)
-		tree := o.rebuilt.Tree(ctx, key.TreeID)
-		incPtr, ok := tree.Items(ctx).Load(key.Key)
+		tree := o.rebuilt.RebuiltTree(ctx, key.TreeID)
+		incPtr, ok := tree.RebuiltItems(ctx).Load(key.Key)
 		if !ok {
 			panic(fmt.Errorf("should not happen: failed to load already-added item: %v", key))
 		}
-		excPtr, ok := tree.PotentialItems(ctx).Load(key.Key)
-		if ok && tree.ShouldReplace(incPtr.Node, excPtr.Node) {
-			wantKey := WantWithTree{
+		excPtr, ok := tree.RebuiltPotentialItems(ctx).Load(key.Key)
+		if ok && tree.RebuiltShouldReplace(incPtr.Node, excPtr.Node) {
+			wantKey := wantWithTree{
 				TreeID: key.TreeID,
 				Key:    wantFromKey(key.Key),
 			}
-			o.wantAugment(ctx, wantKey, tree.LeafToRoots(ctx, excPtr.Node))
+			o.wantAugment(ctx, wantKey, tree.RebuiltLeafToRoots(ctx, excPtr.Node))
 			progress.NumAugments = o.numAugments
 			progress.NumAugmentTrees = len(o.augmentQueue)
 			progressWriter.Set(progress)
@@ -270,7 +266,7 @@ func (o *rebuilder) processSettledItemQueue(ctx context.Context) error {
 			ctx := dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.rebuild.process.item", key)
 			item := keyAndBody{
 				keyAndTree: key,
-				Body:       o.rebuilt.Tree(ctx, key.TreeID).ReadItem(ctx, key.Key),
+				Body:       o.rebuilt.RebuiltTree(ctx, key.TreeID).ReadItem(ctx, key.Key),
 			}
 			select {
 			case itemChan <- item:
@@ -286,7 +282,7 @@ func (o *rebuilder) processSettledItemQueue(ctx context.Context) error {
 			ctx := dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.rebuild.process.item", item.keyAndTree)
 			o.curKey.TreeID = item.TreeID
 			o.curKey.Key.Val = item.Key
-			btrfscheck.HandleItem(ctx, o, item.TreeID, btrfstree.Item{
+			btrfscheck.HandleItem(ctx, graphCallbacks{o}, item.TreeID, btrfstree.Item{
 				Key:  item.Key,
 				Body: item.Body,
 			})
@@ -337,7 +333,7 @@ func (o *rebuilder) processAugmentQueue(ctx context.Context) error {
 			progressWriter.Set(progress)
 			// This will call o.AddedItem as nescessary, which
 			// inserts to o.addedItemQueue.
-			o.rebuilt.Tree(ctx, treeID).AddRoot(ctx, nodeAddr)
+			o.rebuilt.RebuiltTree(ctx, treeID).RebuiltAddRoot(ctx, nodeAddr)
 			progress.N++
 		}
 	}
@@ -385,8 +381,8 @@ func (o *rebuilder) resolveTreeAugments(ctx context.Context, treeID btrfsprim.Ob
 		} else {
 			choices[choice] = ChoiceInfo{
 				Count:      1,
-				Distance:   discardOK(o.rebuilt.Tree(ctx, treeID).COWDistance(o.graph.Nodes[choice].Owner)),
-				Generation: o.graph.Nodes[choice].Generation,
+				Distance:   discardOK(o.rebuilt.RebuiltTree(ctx, treeID).RebuiltCOWDistance(o.scan.Graph.Nodes[choice].Owner)),
+				Generation: o.scan.Graph.Nodes[choice].Generation,
 			}
 		}
 	}
@@ -399,8 +395,8 @@ func (o *rebuilder) resolveTreeAugments(ctx context.Context, treeID btrfsprim.Ob
 			} else {
 				choices[choice] = ChoiceInfo{
 					Count:      1,
-					Distance:   discardOK(o.rebuilt.Tree(ctx, treeID).COWDistance(o.graph.Nodes[choice].Owner)),
-					Generation: o.graph.Nodes[choice].Generation,
+					Distance:   discardOK(o.rebuilt.RebuiltTree(ctx, treeID).RebuiltCOWDistance(o.scan.Graph.Nodes[choice].Owner)),
+					Generation: o.scan.Graph.Nodes[choice].Generation,
 				}
 			}
 		}
@@ -520,7 +516,7 @@ func (o *rebuilder) resolveTreeAugments(ctx context.Context, treeID btrfsprim.Ob
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
-func (queue *treeAugmentQueue) has(wantKey Want) bool {
+func (queue *treeAugmentQueue) has(wantKey want) bool {
 	if queue != nil {
 		if queue.zero != nil {
 			if _, ok := queue.zero[wantKey]; ok {
@@ -541,7 +537,7 @@ func (queue *treeAugmentQueue) has(wantKey Want) bool {
 	return false
 }
 
-func (queue *treeAugmentQueue) store(wantKey Want, choices containers.Set[btrfsvol.LogicalAddr]) {
+func (queue *treeAugmentQueue) store(wantKey want, choices containers.Set[btrfsvol.LogicalAddr]) {
 	if len(choices) == 0 && wantKey.OffsetType > offsetExact {
 		// This wantKey is unlikely to come up again, so it's
 		// not worth the RAM of storing a negative result.
@@ -550,27 +546,27 @@ func (queue *treeAugmentQueue) store(wantKey Want, choices containers.Set[btrfsv
 	switch len(choices) {
 	case 0:
 		if queue.zero == nil {
-			queue.zero = make(map[Want]struct{})
+			queue.zero = make(map[want]struct{})
 		}
 		queue.zero[wantKey] = struct{}{}
 	case 1:
 		if queue.single == nil {
-			queue.single = make(map[Want]btrfsvol.LogicalAddr)
+			queue.single = make(map[want]btrfsvol.LogicalAddr)
 		}
 		queue.single[wantKey] = choices.TakeOne()
 	default:
 		if queue.multi == nil {
-			queue.multi = make(map[Want]containers.Set[btrfsvol.LogicalAddr])
+			queue.multi = make(map[want]containers.Set[btrfsvol.LogicalAddr])
 		}
 		queue.multi[wantKey] = choices
 	}
 }
 
-func (o *rebuilder) hasAugment(wantKey WantWithTree) bool {
+func (o *rebuilder) hasAugment(wantKey wantWithTree) bool {
 	return o.augmentQueue[wantKey.TreeID].has(wantKey.Key)
 }
 
-func (o *rebuilder) wantAugment(ctx context.Context, wantKey WantWithTree, choices containers.Set[btrfsvol.LogicalAddr]) {
+func (o *rebuilder) wantAugment(ctx context.Context, wantKey wantWithTree, choices containers.Set[btrfsvol.LogicalAddr]) {
 	if o.augmentQueue[wantKey.TreeID] == nil {
 		o.augmentQueue[wantKey.TreeID] = new(treeAugmentQueue)
 	}
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
index a422a47..92b5ee5 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
@@ -13,8 +13,12 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
 )
 
+type forrestCallbacks struct {
+	*rebuilder
+}
+
 // AddedItem implements btrfsutil.RebuiltForrestCallbacks.
-func (o *rebuilder) AddedItem(_ context.Context, tree btrfsprim.ObjID, key btrfsprim.Key) {
+func (o forrestCallbacks) AddedItem(_ context.Context, tree btrfsprim.ObjID, key btrfsprim.Key) {
 	o.addedItemQueue.Insert(keyAndTree{
 		TreeID: tree,
 		Key:    key,
@@ -22,17 +26,17 @@ func (o *rebuilder) AddedItem(_ context.Context, tree btrfsprim.ObjID, key btrfs
 }
 
 // AddedRoot implements btrfsutil.RebuiltForrestCallbacks.
-func (o *rebuilder) AddedRoot(_ context.Context, tree btrfsprim.ObjID, _ btrfsvol.LogicalAddr) {
+func (o forrestCallbacks) AddedRoot(_ context.Context, tree btrfsprim.ObjID, _ btrfsvol.LogicalAddr) {
 	if retries := o.retryItemQueue[tree]; retries != nil {
 		o.addedItemQueue.InsertFrom(retries)
 	}
 }
 
 // LookupRoot implements btrfsutil.RebuiltForrestCallbacks.
-func (o *rebuilder) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool) {
-	wantKey := WantWithTree{
+func (o forrestCallbacks) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool) {
+	wantKey := wantWithTree{
 		TreeID: btrfsprim.ROOT_TREE_OBJECTID,
-		Key: Want{
+		Key: want{
 			ObjectID:   tree,
 			ItemType:   btrfsitem.ROOT_ITEM_KEY,
 			OffsetType: offsetAny,
@@ -44,13 +48,13 @@ func (o *rebuilder) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offse
 		o.enqueueRetry(btrfsprim.ROOT_TREE_OBJECTID)
 		return 0, btrfsitem.Root{}, false
 	}
-	itemBody := o.rebuilt.Tree(ctx, wantKey.TreeID).ReadItem(ctx, foundKey)
+	itemBody := o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).ReadItem(ctx, foundKey)
 	defer itemBody.Free()
 	switch itemBody := itemBody.(type) {
 	case *btrfsitem.Root:
 		return btrfsprim.Generation(foundKey.Offset), *itemBody, true
 	case *btrfsitem.Error:
-		o.FSErr(ctx, fmt.Errorf("error decoding item: %v: %w", foundKey, itemBody.Err))
+		graphCallbacks(o).FSErr(ctx, fmt.Errorf("error decoding item: %v: %w", foundKey, itemBody.Err))
 		return 0, btrfsitem.Root{}, false
 	default:
 		// This is a panic because the item decoder should not emit ROOT_ITEM items as anything but
@@ -60,8 +64,8 @@ func (o *rebuilder) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offse
 }
 
 // LookupUUID implements btrfsutil.RebuiltForrestCallbacks.
-func (o *rebuilder) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool) {
-	wantKey := WantWithTree{
+func (o forrestCallbacks) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool) {
+	wantKey := wantWithTree{
 		TreeID: btrfsprim.UUID_TREE_OBJECTID,
 		Key:    wantFromKey(btrfsitem.UUIDToKey(uuid)),
 	}
@@ -70,13 +74,13 @@ func (o *rebuilder) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btr
 		o.enqueueRetry(btrfsprim.UUID_TREE_OBJECTID)
 		return 0, false
 	}
-	itemBody := o.rebuilt.Tree(ctx, wantKey.TreeID).ReadItem(ctx, wantKey.Key.Key())
+	itemBody := o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).ReadItem(ctx, wantKey.Key.Key())
 	defer itemBody.Free()
 	switch itemBody := itemBody.(type) {
 	case *btrfsitem.UUIDMap:
 		return itemBody.ObjID, true
 	case *btrfsitem.Error:
-		o.FSErr(ctx, fmt.Errorf("error decoding item: %v: %w", wantKey, itemBody.Err))
+		graphCallbacks(o).FSErr(ctx, fmt.Errorf("error decoding item: %v: %w", wantKey, itemBody.Err))
 		return 0, false
 	default:
 		// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wantcb.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wantcb.go
index 704f4ee..eff2a83 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wantcb.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wantcb.go
@@ -19,16 +19,20 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
 )
 
+type graphCallbacks struct {
+	*rebuilder
+}
+
 // FSErr implements btrfscheck.GraphCallbacks.
-func (*rebuilder) FSErr(ctx context.Context, e error) {
+func (graphCallbacks) FSErr(ctx context.Context, e error) {
 	dlog.Errorf(ctx, "filesystem error: %v", e)
 }
 
 // Want implements btrfscheck.GraphCallbacks.
-func (o *rebuilder) Want(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, typ btrfsprim.ItemType) {
-	wantKey := WantWithTree{
+func (o graphCallbacks) Want(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, typ btrfsprim.ItemType) {
+	wantKey := wantWithTree{
 		TreeID: treeID,
-		Key: Want{
+		Key: want{
 			ObjectID:   objID,
 			ItemType:   typ,
 			OffsetType: offsetAny,
@@ -38,8 +42,8 @@ func (o *rebuilder) Want(ctx context.Context, reason string, treeID btrfsprim.Ob
 	o._want(ctx, wantKey)
 }
 
-func (o *rebuilder) _want(ctx context.Context, wantKey WantWithTree) (key btrfsprim.Key, ok bool) {
-	if o.rebuilt.Tree(ctx, wantKey.TreeID) == nil {
+func (o *rebuilder) _want(ctx context.Context, wantKey wantWithTree) (key btrfsprim.Key, ok bool) {
+	if o.rebuilt.RebuiltTree(ctx, wantKey.TreeID) == nil {
 		o.enqueueRetry(wantKey.TreeID)
 		return btrfsprim.Key{}, false
 	}
@@ -47,7 +51,7 @@ func (o *rebuilder) _want(ctx context.Context, wantKey WantWithTree) (key btrfsp
 	// check if we already have it
 
 	tgt := wantKey.Key.Key()
-	if key, _, ok := o.rebuilt.Tree(ctx, wantKey.TreeID).Items(ctx).Search(func(key btrfsprim.Key, _ btrfsutil.ItemPtr) int {
+	if key, _, ok := o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltItems(ctx).Search(func(key btrfsprim.Key, _ btrfsutil.ItemPtr) int {
 		key.Offset = 0
 		return tgt.Compare(key)
 	}); ok {
@@ -60,13 +64,13 @@ func (o *rebuilder) _want(ctx context.Context, wantKey WantWithTree) (key btrfsp
 		return btrfsprim.Key{}, false
 	}
 	wants := make(containers.Set[btrfsvol.LogicalAddr])
-	o.rebuilt.Tree(ctx, wantKey.TreeID).PotentialItems(ctx).Subrange(
+	o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltPotentialItems(ctx).Subrange(
 		func(k btrfsprim.Key, _ btrfsutil.ItemPtr) int {
 			k.Offset = 0
 			return tgt.Compare(k)
 		},
 		func(_ btrfsprim.Key, v btrfsutil.ItemPtr) bool {
-			wants.InsertFrom(o.rebuilt.Tree(ctx, wantKey.TreeID).LeafToRoots(ctx, v.Node))
+			wants.InsertFrom(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltLeafToRoots(ctx, v.Node))
 			return true
 		})
 	o.wantAugment(ctx, wantKey, wants)
@@ -74,10 +78,10 @@ func (o *rebuilder) _want(ctx context.Context, wantKey WantWithTree) (key btrfsp
 }
 
 // WantOff implements btrfscheck.GraphCallbacks.
-func (o *rebuilder) WantOff(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, typ btrfsprim.ItemType, off uint64) {
-	wantKey := WantWithTree{
+func (o graphCallbacks) WantOff(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, typ btrfsprim.ItemType, off uint64) {
+	wantKey := wantWithTree{
 		TreeID: treeID,
-		Key: Want{
+		Key: want{
 			ObjectID:   objID,
 			ItemType:   typ,
 			OffsetType: offsetExact,
@@ -88,8 +92,8 @@ func (o *rebuilder) WantOff(ctx context.Context, reason string, treeID btrfsprim
 	o._wantOff(ctx, wantKey)
 }
 
-func (o *rebuilder) _wantOff(ctx context.Context, wantKey WantWithTree) (ok bool) {
-	if o.rebuilt.Tree(ctx, wantKey.TreeID) == nil {
+func (o *rebuilder) _wantOff(ctx context.Context, wantKey wantWithTree) (ok bool) {
+	if o.rebuilt.RebuiltTree(ctx, wantKey.TreeID) == nil {
 		o.enqueueRetry(wantKey.TreeID)
 		return false
 	}
@@ -97,7 +101,7 @@ func (o *rebuilder) _wantOff(ctx context.Context, wantKey WantWithTree) (ok bool
 	// check if we already have it
 
 	tgt := wantKey.Key.Key()
-	if _, ok := o.rebuilt.Tree(ctx, wantKey.TreeID).Items(ctx).Load(tgt); ok {
+	if _, ok := o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltItems(ctx).Load(tgt); ok {
 		return true
 	}
 
@@ -107,10 +111,10 @@ func (o *rebuilder) _wantOff(ctx context.Context, wantKey WantWithTree) (ok bool
 		return false
 	}
 	wants := make(containers.Set[btrfsvol.LogicalAddr])
-	o.rebuilt.Tree(ctx, wantKey.TreeID).PotentialItems(ctx).Subrange(
+	o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltPotentialItems(ctx).Subrange(
 		func(k btrfsprim.Key, _ btrfsutil.ItemPtr) int { return tgt.Compare(k) },
 		func(_ btrfsprim.Key, v btrfsutil.ItemPtr) bool {
-			wants.InsertFrom(o.rebuilt.Tree(ctx, wantKey.TreeID).LeafToRoots(ctx, v.Node))
+			wants.InsertFrom(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID).RebuiltLeafToRoots(ctx, v.Node))
 			return true
 		})
 	o.wantAugment(ctx, wantKey, wants)
@@ -118,10 +122,10 @@ func (o *rebuilder) _wantOff(ctx context.Context, wantKey WantWithTree) (ok bool
 }
 
 // WantDirIndex implements btrfscheck.GraphCallbacks.
-func (o *rebuilder) WantDirIndex(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, name []byte) {
-	wantKey := WantWithTree{
+func (o graphCallbacks) WantDirIndex(ctx context.Context, reason string, treeID btrfsprim.ObjID, objID btrfsprim.ObjID, name []byte) {
+	wantKey := wantWithTree{
 		TreeID: treeID,
-		Key: Want{
+		Key: want{
 			ObjectID:   objID,
 			ItemType:   btrfsitem.DIR_INDEX_KEY,
 			OffsetType: offsetName,
@@ -130,7 +134,7 @@ func (o *rebuilder) WantDirIndex(ctx context.Context, reason string, treeID btrf
 	}
 	ctx = withWant(ctx, logFieldItemWant, reason, wantKey)
 
-	if o.rebuilt.Tree(ctx, treeID) == nil {
+	if o.rebuilt.RebuiltTree(ctx, treeID) == nil {
 		o.enqueueRetry(treeID)
 		return
 	}
@@ -139,13 +143,13 @@ func (o *rebuilder) WantDirIndex(ctx context.Context, reason string, treeID btrf
 
 	tgt := wantKey.Key.Key()
 	found := false
-	o.rebuilt.Tree(ctx, treeID).Items(ctx).Subrange(
+	o.rebuilt.RebuiltTree(ctx, treeID).RebuiltItems(ctx).Subrange(
 		func(key btrfsprim.Key, _ btrfsutil.ItemPtr) int {
 			key.Offset = 0
 			return tgt.Compare(key)
 		},
 		func(_ btrfsprim.Key, ptr btrfsutil.ItemPtr) bool {
-			if itemName, ok := o.keyIO.Names[ptr]; ok && bytes.Equal(itemName, name) {
+			if itemName, ok := o.scan.Names[ptr]; ok && bytes.Equal(itemName, name) {
 				found = true
 			}
 			return !found
@@ -160,21 +164,21 @@ func (o *rebuilder) WantDirIndex(ctx context.Context, reason string, treeID btrf
 		return
 	}
 	wants := make(containers.Set[btrfsvol.LogicalAddr])
-	o.rebuilt.Tree(ctx, treeID).PotentialItems(ctx).Subrange(
+	o.rebuilt.RebuiltTree(ctx, treeID).RebuiltPotentialItems(ctx).Subrange(
 		func(key btrfsprim.Key, _ btrfsutil.ItemPtr) int {
 			key.Offset = 0
 			return tgt.Compare(key)
 		},
 		func(_ btrfsprim.Key, ptr btrfsutil.ItemPtr) bool {
-			if itemName, ok := o.keyIO.Names[ptr]; ok && bytes.Equal(itemName, name) {
-				wants.InsertFrom(o.rebuilt.Tree(ctx, treeID).LeafToRoots(ctx, ptr.Node))
+			if itemName, ok := o.scan.Names[ptr]; ok && bytes.Equal(itemName, name) {
+				wants.InsertFrom(o.rebuilt.RebuiltTree(ctx, treeID).RebuiltLeafToRoots(ctx, ptr.Node))
 			}
 			return true
 		})
 	o.wantAugment(ctx, wantKey, wants)
 }
 
-func (o *rebuilder) _walkRange(
+func (o graphCallbacks) _walkRange(
 	ctx context.Context,
 	items *containers.SortedMap[btrfsprim.Key, btrfsutil.ItemPtr],
 	treeID, objID btrfsprim.ObjID, typ btrfsprim.ItemType,
@@ -203,7 +207,7 @@ func (o *rebuilder) _walkRange(
 			}
 		},
 		func(runKey btrfsprim.Key, runPtr btrfsutil.ItemPtr) bool {
-			runSizeAndErr, ok := o.keyIO.Sizes[runPtr]
+			runSizeAndErr, ok := o.scan.Sizes[runPtr]
 			if !ok {
 				panic(fmt.Errorf("should not happen: %v (%v) did not have a size recorded",
 					runPtr, keyAndTree{TreeID: treeID, Key: runKey}))
@@ -239,14 +243,14 @@ func (a gap) Compare(b gap) int {
 	return containers.NativeCompare(a.Beg, b.Beg)
 }
 
-func (o *rebuilder) _wantRange(
+func (o graphCallbacks) _wantRange(
 	ctx context.Context, reason string,
 	treeID btrfsprim.ObjID, objID btrfsprim.ObjID, typ btrfsprim.ItemType,
 	beg, end uint64,
 ) {
-	wantKey := WantWithTree{
+	wantKey := wantWithTree{
 		TreeID: treeID,
-		Key: Want{
+		Key: want{
 			ObjectID:   objID,
 			ItemType:   typ,
 			OffsetType: offsetAny,
@@ -255,7 +259,7 @@ func (o *rebuilder) _wantRange(
 	ctx = withWant(ctx, logFieldItemWant, reason, wantKey)
 	wantKey.Key.OffsetType = offsetRange
 
-	if o.rebuilt.Tree(ctx, treeID) == nil {
+	if o.rebuilt.RebuiltTree(ctx, treeID) == nil {
 		o.enqueueRetry(treeID)
 		return
 	}
@@ -271,7 +275,7 @@ func (o *rebuilder) _wantRange(
 	})
 	o._walkRange(
 		ctx,
-		o.rebuilt.Tree(ctx, treeID).Items(ctx),
+		o.rebuilt.RebuiltTree(ctx, treeID).RebuiltItems(ctx),
 		treeID, objID, typ, beg, end,
 		func(runKey btrfsprim.Key, _ btrfsutil.ItemPtr, runBeg, runEnd uint64) {
 			var overlappingGaps []*containers.RBNode[gap]
@@ -316,7 +320,7 @@ func (o *rebuilder) _wantRange(
 	if gaps.Len() == 0 {
 		return
 	}
-	potentialItems := o.rebuilt.Tree(ctx, treeID).PotentialItems(ctx)
+	potentialItems := o.rebuilt.RebuiltTree(ctx, treeID).RebuiltPotentialItems(ctx)
 	gaps.Range(func(rbNode *containers.RBNode[gap]) bool {
 		gap := rbNode.Value
 		last := gap.Beg
@@ -336,7 +340,7 @@ func (o *rebuilder) _wantRange(
 				wantKey.Key.OffsetLow = gap.Beg
 				wantKey.Key.OffsetHigh = gap.End
 				wantCtx := withWant(ctx, logFieldItemWant, reason, wantKey)
-				o.wantAugment(wantCtx, wantKey, o.rebuilt.Tree(wantCtx, treeID).LeafToRoots(wantCtx, v.Node))
+				o.wantAugment(wantCtx, wantKey, o.rebuilt.RebuiltTree(wantCtx, treeID).RebuiltLeafToRoots(wantCtx, v.Node))
 				last = runEnd
 			})
 		if last < gap.End {
@@ -353,10 +357,10 @@ func (o *rebuilder) _wantRange(
 // WantCSum implements btrfscheck.GraphCallbacks.
 //
 // interval is [beg, end)
-func (o *rebuilder) WantCSum(ctx context.Context, reason string, inodeTree, inode btrfsprim.ObjID, beg, end btrfsvol.LogicalAddr) {
-	inodeWant := WantWithTree{
+func (o graphCallbacks) WantCSum(ctx context.Context, reason string, inodeTree, inode btrfsprim.ObjID, beg, end btrfsvol.LogicalAddr) {
+	inodeWant := wantWithTree{
 		TreeID: inodeTree,
-		Key: Want{
+		Key: want{
 			ObjectID:   inode,
 			ItemType:   btrfsitem.INODE_ITEM_KEY,
 			OffsetType: offsetExact,
@@ -368,11 +372,11 @@ func (o *rebuilder) WantCSum(ctx context.Context, reason string, inodeTree, inod
 		o.enqueueRetry(inodeTree)
 		return
 	}
-	inodePtr, ok := o.rebuilt.Tree(inodeCtx, inodeTree).Items(inodeCtx).Load(inodeWant.Key.Key())
+	inodePtr, ok := o.rebuilt.RebuiltTree(inodeCtx, inodeTree).RebuiltItems(inodeCtx).Load(inodeWant.Key.Key())
 	if !ok {
 		panic(fmt.Errorf("should not happen: could not load key: %v", inodeWant))
 	}
-	inodeFlags, ok := o.keyIO.Flags[inodePtr]
+	inodeFlags, ok := o.scan.Flags[inodePtr]
 	if !ok {
 		panic(fmt.Errorf("should not happen: INODE_ITEM did not have flags recorded"))
 	}
@@ -392,7 +396,7 @@ func (o *rebuilder) WantCSum(ctx context.Context, reason string, inodeTree, inod
 }
 
 // WantFileExt implements btrfscheck.GraphCallbacks.
-func (o *rebuilder) WantFileExt(ctx context.Context, reason string, treeID btrfsprim.ObjID, ino btrfsprim.ObjID, size int64) {
+func (o graphCallbacks) WantFileExt(ctx context.Context, reason string, treeID btrfsprim.ObjID, ino btrfsprim.ObjID, size int64) {
 	o._wantRange(
 		ctx, reason,
 		treeID, ino, btrfsprim.EXTENT_DATA_KEY,
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wanttyp.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wanttyp.go
index 8fe8a49..6c9d72b 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wanttyp.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_wanttyp.go
@@ -23,8 +23,8 @@ const (
 	offsetName
 )
 
-type Want struct {
-	// TODO(lukeshu): Delete the 'Want' type in favor of
+type want struct {
+	// TODO(lukeshu): Delete the 'want' type in favor of
 	// btrfstree.Search.
 	ObjectID   btrfsprim.ObjID
 	ItemType   btrfsprim.ItemType
@@ -34,7 +34,7 @@ type Want struct {
 	OffsetName string
 }
 
-func (a Want) Compare(b Want) int {
+func (a want) Compare(b want) int {
 	if d := containers.NativeCompare(a.ObjectID, b.ObjectID); d != 0 {
 		return d
 	}
@@ -56,7 +56,7 @@ func (a Want) Compare(b Want) int {
 	return 0
 }
 
-func (o Want) Key() btrfsprim.Key {
+func (o want) Key() btrfsprim.Key {
 	return btrfsprim.Key{
 		ObjectID: o.ObjectID,
 		ItemType: o.ItemType,
@@ -64,8 +64,8 @@ func (o Want) Key() btrfsprim.Key {
 	}
 }
 
-func wantFromKey(k btrfsprim.Key) Want {
-	return Want{
+func wantFromKey(k btrfsprim.Key) want {
+	return want{
 		ObjectID:   k.ObjectID,
 		ItemType:   k.ItemType,
 		OffsetType: offsetExact,
@@ -73,7 +73,7 @@ func wantFromKey(k btrfsprim.Key) Want {
 	}
 }
 
-func (o Want) String() string {
+func (o want) String() string {
 	switch o.OffsetType {
 	case offsetAny:
 		return fmt.Sprintf("{%v %v ?}", o.ObjectID, o.ItemType)
@@ -88,12 +88,12 @@ func (o Want) String() string {
 	}
 }
 
-type WantWithTree struct {
+type wantWithTree struct {
 	TreeID btrfsprim.ObjID
-	Key    Want
+	Key    want
 }
 
-func (o WantWithTree) String() string {
+func (o wantWithTree) String() string {
 	return fmt.Sprintf("tree=%v key=%v", o.TreeID, o.Key)
 }
 
@@ -102,7 +102,7 @@ const (
 	logFieldTreeWant = "btrfs.util.rebuilt-forrest.add-tree.want"
 )
 
-func withWant(ctx context.Context, logField, reason string, wantKey WantWithTree) context.Context {
+func withWant(ctx context.Context, logField, reason string, wantKey wantWithTree) context.Context {
 	ctx = dlog.WithField(ctx, logField+".reason", reason)
 	ctx = dlog.WithField(ctx, logField+".key", wantKey)
 	return ctx
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/scan.go b/cmd/btrfs-rec/inspect/rebuildtrees/scan.go
index ba56c5b..ada9f6f 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/scan.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/scan.go
@@ -6,11 +6,14 @@ package rebuildtrees
 
 import (
 	"context"
+	"fmt"
 	"time"
 
 	"github.com/datawire/dlib/dlog"
 
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsutil"
@@ -18,11 +21,31 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
 )
 
-func ScanDevices(ctx context.Context, fs *btrfs.FS, nodeList []btrfsvol.LogicalAddr) (btrfstree.Superblock, btrfsutil.Graph, *btrfsutil.KeyIO, error) {
+type SizeAndErr struct {
+	Size uint64
+	Err  error
+}
+
+type FlagsAndErr struct {
+	NoDataSum bool
+	Err       error
+}
+
+type ScanDevicesResult struct {
+	Superblock btrfstree.Superblock
+
+	Graph btrfsutil.Graph
+
+	Flags map[btrfsutil.ItemPtr]FlagsAndErr // INODE_ITEM
+	Names map[btrfsutil.ItemPtr][]byte      // DIR_INDEX
+	Sizes map[btrfsutil.ItemPtr]SizeAndErr  // EXTENT_CSUM and EXTENT_DATA
+}
+
+func ScanDevices(ctx context.Context, fs *btrfs.FS, nodeList []btrfsvol.LogicalAddr) (ScanDevicesResult, error) {
 	dlog.Info(ctx, "Reading superblock...")
 	sb, err := fs.Superblock()
 	if err != nil {
-		return btrfstree.Superblock{}, btrfsutil.Graph{}, nil, err
+		return ScanDevicesResult{}, err
 	}
 
 	dlog.Infof(ctx, "Reading node data from FS...")
@@ -33,26 +56,32 @@ func ScanDevices(ctx context.Context, fs *btrfs.FS, nodeList []btrfsvol.LogicalA
 		dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.read.substep", "read-nodes"),
 		dlog.LogLevelInfo, textui.Tunable(1*time.Second))
 
-	nodeGraph := btrfsutil.NewGraph(*sb)
-	keyIO := btrfsutil.NewKeyIO(fs, *sb)
+	ret := ScanDevicesResult{
+		Superblock: *sb,
+
+		Graph: btrfsutil.NewGraph(*sb),
+
+		Flags: make(map[btrfsutil.ItemPtr]FlagsAndErr),
+		Names: make(map[btrfsutil.ItemPtr][]byte),
+		Sizes: make(map[btrfsutil.ItemPtr]SizeAndErr),
+	}
 
 	progressWriter.Set(stats)
 	for _, laddr := range nodeList {
 		if err := ctx.Err(); err != nil {
-			return btrfstree.Superblock{}, btrfsutil.Graph{}, nil, err
+			return ScanDevicesResult{}, err
 		}
-		nodeRef, err := btrfstree.ReadNode[btrfsvol.LogicalAddr](fs, *sb, laddr, btrfstree.NodeExpectations{
-			LAddr: containers.Optional[btrfsvol.LogicalAddr]{OK: true, Val: laddr},
+		node, err := btrfstree.ReadNode[btrfsvol.LogicalAddr](fs, *sb, laddr, btrfstree.NodeExpectations{
+			LAddr: containers.OptionalValue(laddr),
 		})
 		if err != nil {
-			btrfstree.FreeNodeRef(nodeRef)
-			return btrfstree.Superblock{}, btrfsutil.Graph{}, nil, err
+			node.Free()
+			return ScanDevicesResult{}, err
 		}
 
-		nodeGraph.InsertNode(nodeRef)
-		keyIO.InsertNode(nodeRef)
+		ret.insertNode(node)
 
-		btrfstree.FreeNodeRef(nodeRef)
+		node.Free()
 
 		stats.N++
 		progressWriter.Set(stats)
@@ -64,10 +93,54 @@ func ScanDevices(ctx context.Context, fs *btrfs.FS, nodeList []btrfsvol.LogicalA
 	dlog.Info(ctx, "... done reading node data")
 
 	ctx = dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.read.substep", "check")
-	if err := nodeGraph.FinalCheck(ctx, fs, *sb); err != nil {
-		return btrfstree.Superblock{}, btrfsutil.Graph{}, nil, err
+	if err := ret.Graph.FinalCheck(ctx, fs, *sb); err != nil {
+		return ScanDevicesResult{}, err
 	}
-	keyIO.SetGraph(*nodeGraph)
 
-	return *sb, *nodeGraph, keyIO, nil
+	return ret, nil
+}
+
+func (o *ScanDevicesResult) insertNode(node *btrfstree.Node) {
+	o.Graph.InsertNode(node)
+	for i, item := range node.BodyLeaf {
+		ptr := btrfsutil.ItemPtr{
+			Node: node.Head.Addr,
+			Slot: i,
+		}
+		switch itemBody := item.Body.(type) {
+		case *btrfsitem.Inode:
+			o.Flags[ptr] = FlagsAndErr{
+				NoDataSum: itemBody.Flags.Has(btrfsitem.INODE_NODATASUM),
+				Err:       nil,
+			}
+		case *btrfsitem.DirEntry:
+			if item.Key.ItemType == btrfsprim.DIR_INDEX_KEY {
+				o.Names[ptr] = append([]byte(nil), itemBody.Name...)
+			}
+		case *btrfsitem.ExtentCSum:
+			o.Sizes[ptr] = SizeAndErr{
+				Size: uint64(itemBody.Size()),
+				Err:  nil,
+			}
+		case *btrfsitem.FileExtent:
+			size, err := itemBody.Size()
+			o.Sizes[ptr] = SizeAndErr{
+				Size: uint64(size),
+				Err:  err,
+			}
+		case *btrfsitem.Error:
+			switch item.Key.ItemType {
+			case btrfsprim.INODE_ITEM_KEY:
+				o.Flags[ptr] = FlagsAndErr{
+					Err: fmt.Errorf("error decoding item: ptr=%v (tree=%v key=%v): %w",
+						ptr, node.Head.Owner, item.Key, itemBody.Err),
+				}
+			case btrfsprim.EXTENT_CSUM_KEY, btrfsprim.EXTENT_DATA_KEY:
+				o.Sizes[ptr] = SizeAndErr{
+					Err: fmt.Errorf("error decoding item: ptr=%v (tree=%v key=%v): %w",
+						ptr, node.Head.Owner, item.Key, itemBody.Err),
+				}
+			}
+		}
+	}
 }
diff --git a/cmd/btrfs-rec/inspect_lsfiles.go b/cmd/btrfs-rec/inspect_lsfiles.go
index a2b46ab..04b5ec5 100644
--- a/cmd/btrfs-rec/inspect_lsfiles.go
+++ b/cmd/btrfs-rec/inspect_lsfiles.go
@@ -6,23 +6,14 @@ package main
 
 import (
 	"bufio"
-	"errors"
-	"fmt"
-	"io"
 	"os"
-	"path"
-	"strings"
 
-	"github.com/datawire/dlib/derror"
 	"github.com/datawire/ocibuild/pkg/cliutil"
 	"github.com/spf13/cobra"
 
+	"git.lukeshu.com/btrfs-progs-ng/cmd/btrfs-rec/inspect/lsfiles"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
-	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
-	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsutil"
-	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
-	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
 )
 
 func init() {
@@ -37,221 +28,10 @@ func init() {
 					err = _err
 				}
 			}()
-			defer func() {
-				if _err := derror.PanicToError(recover()); _err != nil {
-					textui.Fprintf(out, "\n\n%+v\n", _err)
-					err = _err
-				}
-			}()
-			ctx := cmd.Context()
 
-			printSubvol(out, "", true, "/", &btrfs.Subvolume{
-				FS:     btrfsutil.NewOldRebuiltForrest(ctx, fs),
-				TreeID: btrfsprim.FS_TREE_OBJECTID,
-			})
-
-			return nil
+			return lsfiles.LsFiles(
+				out,
+				btrfsutil.NewOldRebuiltForrest(cmd.Context(), fs))
 		}),
 	})
 }
-
-const (
-	tS = "    "
-	tl = "│   "
-	tT = "├── "
-	tL = "└── "
-)
-
-func printText(out io.Writer, prefix string, isLast bool, name, text string) {
-	first, rest := tT, tl
-	if isLast {
-		first, rest = tL, tS
-	}
-	for i, line := range strings.Split(textui.Sprintf("%q %s", name, text), "\n") {
-		_, _ = io.WriteString(out, prefix)
-		if i == 0 {
-			_, _ = io.WriteString(out, first)
-		} else {
-			_, _ = io.WriteString(out, rest)
-		}
-		_, _ = io.WriteString(out, line)
-		_, _ = io.WriteString(out, "\n")
-	}
-}
-
-func printSubvol(out io.Writer, prefix string, isLast bool, name string, subvol *btrfs.Subvolume) {
-	rootInode, err := subvol.GetRootInode()
-	if err != nil {
-		printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v err=%v",
-			subvol.TreeID, fmtErr(err)))
-		return
-	}
-	dir, err := subvol.LoadDir(rootInode)
-	if err != nil {
-		printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v err=%v",
-			subvol.TreeID, fmtErr(err)))
-		return
-	}
-	if name == "/" {
-		printDir(out, prefix, isLast, name, dir)
-		return
-	}
-	printText(out, prefix, isLast, name+"/", textui.Sprintf("subvol_id=%v", subvol.TreeID))
-	if isLast {
-		prefix += tS
-	} else {
-		prefix += tl
-	}
-	printDir(out, prefix, true, name, dir)
-}
-
-func fmtErr(err error) string {
-	errStr := err.Error()
-	if strings.Contains(errStr, "\n") {
-		errStr = "\\\n" + errStr
-	}
-	return errStr
-}
-
-func fmtInode(inode btrfs.BareInode) string {
-	var mode btrfsitem.StatMode
-	if inode.InodeItem == nil {
-		inode.Errs = append(inode.Errs, errors.New("missing INODE_ITEM"))
-	} else {
-		mode = inode.InodeItem.Mode
-	}
-	ret := textui.Sprintf("ino=%v mode=%v", inode.Inode, mode)
-	if len(inode.Errs) > 0 {
-		ret += " err=" + fmtErr(inode.Errs)
-	}
-	return ret
-}
-
-func printDir(out io.Writer, prefix string, isLast bool, name string, dir *btrfs.Dir) {
-	printText(out, prefix, isLast, name+"/", fmtInode(dir.BareInode))
-	if isLast {
-		prefix += tS
-	} else {
-		prefix += tl
-	}
-	for i, childName := range maps.SortedKeys(dir.ChildrenByName) {
-		printDirEntry(
-			out,
-			prefix,
-			i == len(dir.ChildrenByName)-1,
-			dir.SV,
-			path.Join(name, childName),
-			dir.ChildrenByName[childName])
-	}
-}
-
-func printDirEntry(out io.Writer, prefix string, isLast bool, subvol *btrfs.Subvolume, name string, entry btrfsitem.DirEntry) {
-	if len(entry.Data) != 0 {
-		panic(fmt.Errorf("TODO: I don't know how to handle dirent.data: %q", name))
-	}
-	switch entry.Type {
-	case btrfsitem.FT_DIR:
-		switch entry.Location.ItemType {
-		case btrfsitem.INODE_ITEM_KEY:
-			dir, err := subvol.LoadDir(entry.Location.ObjectID)
-			if err != nil {
-				printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
-				return
-			}
-			printDir(out, prefix, isLast, name, dir)
-		case btrfsitem.ROOT_ITEM_KEY:
-			printSubvol(out, prefix, isLast, name, &btrfs.Subvolume{
-				FS:     subvol.FS,
-				TreeID: entry.Location.ObjectID,
-			})
-		default:
-			panic(fmt.Errorf("TODO: I don't know how to handle an FT_DIR with location.ItemType=%v: %q",
-				entry.Location.ItemType, name))
-		}
-	case btrfsitem.FT_SYMLINK:
-		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
-			panic(fmt.Errorf("TODO: I don't know how to handle an FT_SYMLINK with location.ItemType=%v: %q",
-				entry.Location.ItemType, name))
-		}
-		file, err := subvol.LoadFile(entry.Location.ObjectID)
-		if err != nil {
-			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
-			return
-		}
-		printSymlink(out, prefix, isLast, name, file)
-	case btrfsitem.FT_REG_FILE:
-		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
-			panic(fmt.Errorf("TODO: I don't know how to handle an FT_REG_FILE with location.ItemType=%v: %q",
-				entry.Location.ItemType, name))
-		}
-		file, err := subvol.LoadFile(entry.Location.ObjectID)
-		if err != nil {
-			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
-			return
-		}
-		printFile(out, prefix, isLast, name, file)
-	case btrfsitem.FT_SOCK:
-		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
-			panic(fmt.Errorf("TODO: I don't know how to handle an FT_SOCK with location.ItemType=%v: %q",
-				entry.Location.ItemType, name))
-		}
-		file, err := subvol.LoadFile(entry.Location.ObjectID)
-		if err != nil {
-			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
-			return
-		}
-		printSocket(out, prefix, isLast, name, file)
-	case btrfsitem.FT_FIFO:
-		if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
-			panic(fmt.Errorf("TODO: I don't know how to handle an FT_FIFO with location.ItemType=%v: %q",
-				entry.Location.ItemType, name))
-		}
-		file, err := subvol.LoadFile(entry.Location.ObjectID)
-		if err != nil {
-			printText(out, prefix, isLast, name, textui.Sprintf("%v err=%v", entry.Type, fmtErr(err)))
-			return
-		}
-		printPipe(out, prefix, isLast, name, file)
-	default:
-		panic(fmt.Errorf("TODO: I don't know how to handle a fileType=%v: %q",
-			entry.Type, name))
-	}
-}
-
-func printSymlink(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
-	var tgt []byte
-	if file.InodeItem != nil {
-		var err error
-		tgt, err = io.ReadAll(io.NewSectionReader(file, 0, file.InodeItem.Size))
-		if err != nil {
-			file.Errs = append(file.Errs, err)
-		}
-	}
-	printText(out, prefix, isLast, name, textui.Sprintf(
-		"-> %q : %s",
-		tgt,
-		fmtInode(file.BareInode)))
-}
-
-func printFile(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
-	if file.InodeItem != nil {
-		if _, err := io.Copy(io.Discard, io.NewSectionReader(file, 0, file.InodeItem.Size)); err != nil {
-			file.Errs = append(file.Errs, err)
-		}
-	}
-	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
-}
-
-func printSocket(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
-	if file.InodeItem != nil && file.InodeItem.Size > 0 {
-		panic(fmt.Errorf("TODO: I don't know how to handle a socket with size>0: %q", name))
-	}
-	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
-}
-
-func printPipe(out io.Writer, prefix string, isLast bool, name string, file *btrfs.File) {
-	if file.InodeItem != nil && file.InodeItem.Size > 0 {
-		panic(fmt.Errorf("TODO: I don't know how to handle a pipe with size>0: %q", name))
-	}
-	printText(out, prefix, isLast, name, fmtInode(file.BareInode))
-}
diff --git a/cmd/btrfs-rec/inspect_lstrees.go b/cmd/btrfs-rec/inspect_lstrees.go
index 05c3a57..cad1a37 100644
--- a/cmd/btrfs-rec/inspect_lstrees.go
+++ b/cmd/btrfs-rec/inspect_lstrees.go
@@ -19,7 +19,6 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
 	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsutil"
 	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
-	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
 	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
 	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
 	"git.lukeshu.com/btrfs-progs-ng/lib/textui"
@@ -76,16 +75,16 @@ func init() {
 					treeErrCnt++
 				},
 				TreeWalkHandler: btrfstree.TreeWalkHandler{
-					Node: func(_ btrfstree.TreePath, ref *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) error {
-						visitedNodes.Insert(ref.Addr)
+					Node: func(path btrfstree.Path, node *btrfstree.Node) error {
+						visitedNodes.Insert(path.Node(-1).ToNodeAddr)
 						return nil
 					},
-					Item: func(_ btrfstree.TreePath, item btrfstree.Item) error {
+					Item: func(_ btrfstree.Path, item btrfstree.Item) error {
 						typ := item.Key.ItemType
 						treeItemCnt[typ]++
 						return nil
 					},
-					BadItem: func(_ btrfstree.TreePath, item btrfstree.Item) error {
+					BadItem: func(_ btrfstree.Path, item btrfstree.Item) error {
 						typ := item.Key.ItemType
 						treeItemCnt[typ]++
 						return nil
@@ -107,13 +106,13 @@ func init() {
 					}
 					visitedNodes.Insert(laddr)
 					node, err := btrfstree.ReadNode[btrfsvol.LogicalAddr](fs, *sb, laddr, btrfstree.NodeExpectations{
-						LAddr: containers.Optional[btrfsvol.LogicalAddr]{OK: true, Val: laddr},
+						LAddr: containers.OptionalValue(laddr),
 					})
 					if err != nil {
 						treeErrCnt++
 						continue
 					}
-					for _, item := range node.Data.BodyLeaf {
+					for _, item := range node.BodyLeaf {
 						typ := item.Key.ItemType
 						treeItemCnt[typ]++
 					}
diff --git a/cmd/btrfs-rec/inspect_spewitems.go b/cmd/btrfs-rec/inspect_spewitems.go
index d8a65ae..b83e989 100644
--- a/cmd/btrfs-rec/inspect_spewitems.go
+++ b/cmd/btrfs-rec/inspect_spewitems.go
@@ -34,13 +34,13 @@ func init() {
 					dlog.Error(ctx, err)
 				},
 				TreeWalkHandler: btrfstree.TreeWalkHandler{
-					Item: func(path btrfstree.TreePath, item btrfstree.Item) error {
+					Item: func(path btrfstree.Path, item btrfstree.Item) error {
 						textui.Fprintf(os.Stdout, "%s = ", path)
 						spew.Dump(item)
 						_, _ = os.Stdout.WriteString("\n")
 						return nil
 					},
-					BadItem: func(path btrfstree.TreePath, item btrfstree.Item) error {
+					BadItem: func(path btrfstree.Path, item btrfstree.Item) error {
 						textui.Fprintf(os.Stdout, "%s = ", path)
 						spew.Dump(item)
 						_, _ = os.Stdout.WriteString("\n")