wip

4 files changed, 71 insertions, 30 deletions

diff --git a/lib/btrfs/btrfstree/readnode.go b/lib/btrfs/btrfstree/readnode.go
index bb80d20..b1c34e4 100644
--- a/lib/btrfs/btrfstree/readnode.go
+++ b/lib/btrfs/btrfstree/readnode.go
@@ -13,14 +13,26 @@ import (
 	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
 )
 
+type NodeFile interface {
+	diskio.File[btrfsvol.LogicalAddr]
+	Superblock() (*Superblock, error)
+
+	// ParentTree, given a tree ID, returns that tree's parent
+	// tree, if it has one.
+	//
+	//  - non-zero, true : the parent tree ID
+	//
+	//  - 0, true : the tree does not have a parent
+	//
+	//  - any, false : the tree's parent information could not be
+	//    looked up
+	ParentTree(btrfsprim.ObjID) (btrfsprim.ObjID, bool)
+}
+
 // FSReadNode is a utility function to help with implementing the
 // 'NodeSource' interface.
 func FSReadNode(
-	fs interface {
-		diskio.File[btrfsvol.LogicalAddr]
-		Superblock() (*Superblock, error)
-		ParentTree(btrfsprim.ObjID) (btrfsprim.ObjID, bool)
-	},
+	fs NodeFile,
 	path TreePath,
 ) (*diskio.Ref[btrfsvol.LogicalAddr, Node], error) {
 	sb, err := fs.Superblock()
@@ -39,6 +51,11 @@ func FSReadNode(
 			var ok bool
 			exp, ok = fs.ParentTree(exp)
 			if !ok {
+				// Failed lookup up parent info; fail open.
+				return nil
+			}
+			if exp == 0 {
+				// End of the line.
 				return fmt.Errorf("expected owner in %v but claims to have owner=%v",
 					treeParents, owner)
 			}
diff --git a/lib/btrfs/io3_btree.go b/lib/btrfs/io3_btree.go
index 8455eee..26acc22 100644
--- a/lib/btrfs/io3_btree.go
+++ b/lib/btrfs/io3_btree.go
@@ -58,18 +58,23 @@ func (fs *FS) populateTreeUUIDs(ctx context.Context) {
 }
 
 func (fs *FS) ParentTree(tree btrfsprim.ObjID) (btrfsprim.ObjID, bool) {
-	ctx := context.TODO()
-	if tree < btrfsprim.FIRST_FREE_OBJECTID {
+	if tree < btrfsprim.FIRST_FREE_OBJECTID || tree > btrfsprim.LAST_FREE_OBJECTID {
+		// no parent
+		return 0, true
+	}
+	fs.populateTreeUUIDs(context.TODO())
+	parentUUID, ok := fs.cacheTreeParent[tree]
+	if !ok {
+		// could not look up parent info
 		return 0, false
 	}
-	fs.populateTreeUUIDs(ctx)
-	parentUUID := fs.cacheTreeParent[tree]
 	if parentUUID == (btrfsprim.UUID{}) {
-		return 0, false
+		// no parent
+		return 0, true
 	}
 	parentObjID, ok := fs.cacheUUID2ObjID[parentUUID]
 	if !ok {
-		dlog.Errorf(ctx, "dbg: could not resolve parentUUID=%v to an ObjID", parentUUID)
+		// could not look up parent info
 		return 0, false
 	}
 	return parentObjID, true
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/rebuilttrees.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/rebuilttrees.go
index 17116c6..37db791 100644
--- a/lib/btrfsprogs/btrfsinspect/rebuildnodes/rebuilttrees.go
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/rebuilttrees.go
@@ -54,19 +54,26 @@ func (fs *RebuiltTrees) WriteAt(p []byte, off btrfsvol.LogicalAddr) (int, error)
 	return fs.inner.WriteAt(p, off)
 }
 
-// btrfstree.NodeSource backend
+// btrfstree.NodeFile
 
 func (fs *RebuiltTrees) ParentTree(tree btrfsprim.ObjID) (btrfsprim.ObjID, bool) {
-	if tree < btrfsprim.FIRST_FREE_OBJECTID {
+	if tree < btrfsprim.FIRST_FREE_OBJECTID || tree > btrfsprim.LAST_FREE_OBJECTID {
+		// no parent
+		return 0, true
+	}
+	parentUUID, ok := fs.uuidMap.TreeParent[tree]
+	if !ok {
+		// could not look up parent info
 		return 0, false
 	}
-	parentUUID := fs.uuidMap.TreeParent[tree]
 	if parentUUID == (btrfsprim.UUID{}) {
-		return 0, false
+		// no parent
+		return 0, true
 	}
 	parentObjID, ok := fs.uuidMap.UUID2ObjID[parentUUID]
 	if !ok {
-		panic(fmt.Errorf("should not happen: could not resolve parentUUID=%v to an ObjID", parentUUID))
+		// could not look up parent info
+		return 0, false
 	}
 	return parentObjID, true
 }
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap.go
index 0179a6e..95bb3b1 100644
--- a/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap.go
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/uuidmap.go
@@ -6,6 +6,7 @@ package rebuildnodes
 
 import (
 	"context"
+	"encoding/binary"
 	"fmt"
 
 	"github.com/datawire/dlib/dlog"
@@ -26,9 +27,9 @@ type treeUUIDMap struct {
 	TreeParent map[btrfsprim.ObjID]btrfsprim.UUID
 }
 
-func maybeSet[K, V comparable](m map[K]V, k K, v V) error {
+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: %v can't have both %v and %v", k, other, v)
+		return fmt.Errorf("conflict: %s %v can't have both %v and %v", name, k, other, v)
 	}
 	m[k] = v
 	return nil
@@ -71,18 +72,29 @@ func buildTreeUUIDMap(ctx context.Context, fs *btrfs.FS, scanResults btrfsinspec
 				return treeUUIDMap{}, nil
 			}
 			for _, item := range nodeRef.Data.BodyLeaf {
-				itemBody, ok := item.Body.(btrfsitem.Root)
-				if !ok {
-					continue
-				}
-				if err := maybeSet(ret.ObjID2UUID, item.Key.ObjectID, itemBody.UUID); err != nil {
-					return treeUUIDMap{}, err
-				}
-				if err := maybeSet(ret.TreeParent, item.Key.ObjectID, itemBody.ParentUUID); err != nil {
-					return treeUUIDMap{}, err
-				}
-				if err := maybeSet(ret.UUID2ObjID, itemBody.UUID, item.Key.ObjectID); err != nil {
-					return treeUUIDMap{}, err
+				switch itemBody := item.Body.(type) {
+				case btrfsitem.Root:
+					if err := maybeSet("ObjID2UUID", ret.ObjID2UUID, item.Key.ObjectID, itemBody.UUID); err != nil {
+						return treeUUIDMap{}, err
+					}
+					if itemBody.UUID != (btrfsprim.UUID{}) {
+						if err := maybeSet("UUID2ObjID", ret.UUID2ObjID, itemBody.UUID, item.Key.ObjectID); err != nil {
+							return treeUUIDMap{}, err
+						}
+					}
+					if err := maybeSet("ParentUUID", ret.TreeParent, item.Key.ObjectID, itemBody.ParentUUID); err != nil {
+						return treeUUIDMap{}, err
+					}
+				case btrfsitem.UUIDMap:
+					var uuid btrfsprim.UUID
+					binary.BigEndian.PutUint64(uuid[:8], uint64(item.Key.ObjectID))
+					binary.BigEndian.PutUint64(uuid[8:], uint64(item.Key.Offset))
+					if err := maybeSet("ObjID2UUID", ret.ObjID2UUID, itemBody.ObjID, uuid); err != nil {
+						return treeUUIDMap{}, err
+					}
+					if err := maybeSet("UUID2ObjID", ret.UUID2ObjID, uuid, itemBody.ObjID); err != nil {
+						return treeUUIDMap{}, err
+					}
 				}
 			}
 			treeIDs[nodeRef.Data.Head.Owner] = struct{}{}