2 files changed, 128 insertions, 0 deletions
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/scan.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/scan.go
new file mode 100644
index 0000000..98ed097
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/scan.go
@@ -0,0 +1,73 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package uuidmap
+
+import (
+	"fmt"
+
+	"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/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
+)
+
+func maybeSet[K, V comparable](name string, m map[K]V, k K, v V) error {
+	if other, conflict := m[k]; conflict && other != v {
+		return fmt.Errorf("conflict: %s %v can't have both %v and %v", name, k, other, v)
+	}
+	m[k] = v
+	return nil
+}
+
+func New() *UUIDMap {
+	ret := &UUIDMap{
+		ObjID2UUID: make(map[btrfsprim.ObjID]btrfsprim.UUID),
+		UUID2ObjID: make(map[btrfsprim.UUID]btrfsprim.ObjID),
+		TreeParent: make(map[btrfsprim.ObjID]btrfsprim.UUID),
+
+		SeenTrees: make(containers.Set[btrfsprim.ObjID]),
+	}
+
+	// These 4 trees are mentioned directly in the superblock, so
+	// they are always seen.
+	ret.SeenTrees.Insert(btrfsprim.ROOT_TREE_OBJECTID)
+	ret.SeenTrees.Insert(btrfsprim.CHUNK_TREE_OBJECTID)
+	ret.SeenTrees.Insert(btrfsprim.TREE_LOG_OBJECTID)
+	ret.SeenTrees.Insert(btrfsprim.BLOCK_GROUP_TREE_OBJECTID)
+
+	return ret
+}
+
+func (m *UUIDMap) InsertNode(nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) error {
+	for _, item := range nodeRef.Data.BodyLeaf {
+		switch itemBody := item.Body.(type) {
+		case btrfsitem.Root:
+			if err := maybeSet("ObjID2UUID", m.ObjID2UUID, item.Key.ObjectID, itemBody.UUID); err != nil {
+				return err
+			}
+			if itemBody.UUID != (btrfsprim.UUID{}) {
+				if err := maybeSet("UUID2ObjID", m.UUID2ObjID, itemBody.UUID, item.Key.ObjectID); err != nil {
+					return err
+				}
+			}
+			if err := maybeSet("ParentUUID", m.TreeParent, item.Key.ObjectID, itemBody.ParentUUID); err != nil {
+				return err
+			}
+			m.SeenTrees.Insert(item.Key.ObjectID)
+		case btrfsitem.UUIDMap:
+			uuid := btrfsitem.KeyToUUID(item.Key)
+			if err := maybeSet("ObjID2UUID", m.ObjID2UUID, itemBody.ObjID, uuid); err != nil {
+				return err
+			}
+			if err := maybeSet("UUID2ObjID", m.UUID2ObjID, uuid, itemBody.ObjID); err != nil {
+				return err
+			}
+		}
+	}
+	m.SeenTrees.Insert(nodeRef.Data.Head.Owner)
+	return nil
+}
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/uuidmap.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/uuidmap.go
new file mode 100644
index 0000000..32a34d1
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap/uuidmap.go
@@ -0,0 +1,55 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package uuidmap
+
+import (
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+)
+
+type UUIDMap struct {
+	ObjID2UUID map[btrfsprim.ObjID]btrfsprim.UUID
+	UUID2ObjID map[btrfsprim.UUID]btrfsprim.ObjID
+	TreeParent map[btrfsprim.ObjID]btrfsprim.UUID
+
+	SeenTrees containers.Set[btrfsprim.ObjID]
+}
+
+func (m UUIDMap) MissingRootItems() containers.Set[btrfsprim.ObjID] {
+	missing := make(containers.Set[btrfsprim.ObjID])
+	for treeID := range m.SeenTrees {
+		if _, ok := m.ObjID2UUID[treeID]; !ok && treeID != btrfsprim.ROOT_TREE_OBJECTID {
+			missing.Insert(treeID)
+			continue
+		}
+		if _, ok := m.TreeParent[treeID]; !ok && treeID >= btrfsprim.FIRST_FREE_OBJECTID && treeID <= btrfsprim.LAST_FREE_OBJECTID {
+			missing.Insert(treeID)
+		}
+	}
+	return missing
+}
+
+// ParentTree implements btrfstree.NodeFile.
+func (m UUIDMap) ParentTree(tree btrfsprim.ObjID) (btrfsprim.ObjID, bool) {
+	if tree < btrfsprim.FIRST_FREE_OBJECTID || tree > btrfsprim.LAST_FREE_OBJECTID {
+		// no parent
+		return 0, true
+	}
+	parentUUID, ok := m.TreeParent[tree]
+	if !ok {
+		// could not look up parent info
+		return 0, false
+	}
+	if parentUUID == (btrfsprim.UUID{}) {
+		// no parent
+		return 0, true
+	}
+	parentObjID, ok := m.UUID2ObjID[parentUUID]
+	if !ok {
+		// could not look up parent info
+		return 0, false
+	}
+	return parentObjID, true
+}