Clean-up made possible by btrfsutil.RebuiltForrest implementing btrfs.ReadableFS

 - rebuildtrees: Use .ForrestLookup instead of .RebuiltTree where possible

 - btrfsutil: noopRebuiltForrestCallbacks: Use only the generic
   btrfstree.Forrest API

 - btrfsutil: RebuiltForrest, RebuiltTree: Avoid unnecessarily
   reaching into forrest.inner

 - btrfsutil: RebuiltTree: Drop the .ReadItem() method; it duplicates
   .TreeLookup without benefit.

6 files changed, 24 insertions, 45 deletions

diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
index 7e2e49f..77d56ae 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild.go
@@ -159,7 +159,7 @@ func (o *rebuilder) processTreeQueue(ctx context.Context) error {
 		}
 		// This will call o.AddedItem as nescessary, which
 		// inserts to o.addedItemQueue.
-		_, _ = o.rebuilt.RebuiltTree(ctx, o.curKey.TreeID)
+		_, _ = o.rebuilt.ForrestLookup(ctx, o.curKey.TreeID)
 	}
 
 	return nil
@@ -415,7 +415,7 @@ func (o *rebuilder) processSettledItemQueue(ctx context.Context) error {
 			ctx := dlog.WithField(ctx, "btrfs.inspect.rebuild-trees.rebuild.process.item", key)
 			item := keyAndBody{
 				itemToVisit: key,
-				Body:        discardErr(o.rebuilt.RebuiltTree(ctx, key.TreeID)).ReadItem(ctx, key.Key),
+				Body:        discardErr(discardErr(o.rebuilt.RebuiltTree(ctx, key.TreeID)).TreeLookup(ctx, key.Key)).Body,
 			}
 			if key.TreeID == btrfsprim.EXTENT_TREE_OBJECTID &&
 				(key.ItemType == btrfsprim.EXTENT_ITEM_KEY || key.ItemType == btrfsprim.METADATA_ITEM_KEY) {
diff --git a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
index e227cc7..15ad42c 100644
--- a/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
+++ b/cmd/btrfs-rec/inspect/rebuildtrees/rebuild_treecb.go
@@ -36,7 +36,7 @@ func (o forrestCallbacks) AddedRoot(_ context.Context, tree btrfsprim.ObjID, _ b
 }
 
 // LookupRoot implements btrfsutil.RebuiltForrestCallbacks.
-func (o forrestCallbacks) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool) {
+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{
@@ -51,9 +51,9 @@ func (o forrestCallbacks) LookupRoot(ctx context.Context, tree btrfsprim.ObjID)
 		o.enqueueRetry(btrfsprim.ROOT_TREE_OBJECTID)
 		return 0, btrfsitem.Root{}, false
 	}
-	itemBody := discardErr(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID)).ReadItem(ctx, foundKey)
-	defer itemBody.Free()
-	switch itemBody := itemBody.(type) {
+	item, _ := discardErr(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID)).TreeLookup(ctx, foundKey)
+	defer item.Body.Free()
+	switch itemBody := item.Body.(type) {
 	case *btrfsitem.Root:
 		return btrfsprim.Generation(foundKey.Offset), *itemBody, true
 	case *btrfsitem.Error:
@@ -77,9 +77,9 @@ func (o forrestCallbacks) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (
 		o.enqueueRetry(btrfsprim.UUID_TREE_OBJECTID)
 		return 0, false
 	}
-	itemBody := discardErr(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID)).ReadItem(ctx, wantKey.Key.Key())
-	defer itemBody.Free()
-	switch itemBody := itemBody.(type) {
+	item, _ := discardErr(o.rebuilt.RebuiltTree(ctx, wantKey.TreeID)).TreeLookup(ctx, wantKey.Key.Key())
+	defer item.Body.Free()
+	switch itemBody := item.Body.(type) {
 	case *btrfsitem.UUIDMap:
 		return itemBody.ObjID, true
 	case *btrfsitem.Error:
diff --git a/lib/btrfsutil/rebuilt_callbacks.go b/lib/btrfsutil/rebuilt_callbacks.go
index fdc826c..0b51d08 100644
--- a/lib/btrfsutil/rebuilt_callbacks.go
+++ b/lib/btrfsutil/rebuilt_callbacks.go
@@ -10,6 +10,7 @@ import (
 
 	"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"
 )
 
@@ -25,34 +26,25 @@ type RebuiltForrestExtendedCallbacks interface {
 }
 
 type noopRebuiltForrestCallbacks struct {
-	forrest *RebuiltForrest
+	forrest btrfstree.Forrest
 }
 
 func (noopRebuiltForrestCallbacks) AddedRoot(context.Context, btrfsprim.ObjID, btrfsvol.LogicalAddr) {
 }
 
 func (cb noopRebuiltForrestCallbacks) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, _item btrfsitem.Root, ok bool) {
-	rootTree, err := cb.forrest.RebuiltTree(ctx, btrfsprim.ROOT_TREE_OBJECTID)
+	rootTree, err := cb.forrest.ForrestLookup(ctx, btrfsprim.ROOT_TREE_OBJECTID)
 	if err != nil {
 		return 0, btrfsitem.Root{}, false
 	}
-	tgt := btrfsprim.Key{
-		ObjectID: tree,
-		ItemType: btrfsprim.ROOT_ITEM_KEY,
-	}
-	itemKey, itemPtr, ok := rootTree.RebuiltAcquireItems(ctx).Search(func(key btrfsprim.Key, _ ItemPtr) int {
-		key.Offset = 0
-		return tgt.Compare(key)
-	})
-	rootTree.RebuiltReleaseItems()
-	if !ok {
+	item, err := rootTree.TreeSearch(ctx, btrfstree.SearchRootItem(tree))
+	if err != nil {
 		return 0, btrfsitem.Root{}, false
 	}
-	item := cb.forrest.readItem(ctx, itemPtr)
 	defer item.Body.Free()
 	switch itemBody := item.Body.(type) {
 	case *btrfsitem.Root:
-		return btrfsprim.Generation(itemKey.Offset), *itemBody, true
+		return btrfsprim.Generation(item.Key.Offset), *itemBody, true
 	case *btrfsitem.Error:
 		return 0, btrfsitem.Root{}, false
 	default:
@@ -63,17 +55,15 @@ func (cb noopRebuiltForrestCallbacks) LookupRoot(ctx context.Context, tree btrfs
 }
 
 func (cb noopRebuiltForrestCallbacks) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool) {
-	uuidTree, err := cb.forrest.RebuiltTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
+	uuidTree, err := cb.forrest.ForrestLookup(ctx, btrfsprim.UUID_TREE_OBJECTID)
 	if err != nil {
 		return 0, false
 	}
 	tgt := btrfsitem.UUIDToKey(uuid)
-	itemPtr, ok := uuidTree.RebuiltAcquireItems(ctx).Load(tgt)
-	uuidTree.RebuiltReleaseItems()
-	if !ok {
+	item, err := uuidTree.TreeLookup(ctx, tgt)
+	if err != nil {
 		return 0, false
 	}
-	item := cb.forrest.readItem(ctx, itemPtr)
 	defer item.Body.Free()
 	switch itemBody := item.Body.(type) {
 	case *btrfsitem.UUIDMap:
diff --git a/lib/btrfsutil/rebuilt_forrest.go b/lib/btrfsutil/rebuilt_forrest.go
index b935d85..beb7d40 100644
--- a/lib/btrfsutil/rebuilt_forrest.go
+++ b/lib/btrfsutil/rebuilt_forrest.go
@@ -159,16 +159,16 @@ func (ts *RebuiltForrest) rebuildTree(ctx context.Context, treeID btrfsprim.ObjI
 	var root btrfsvol.LogicalAddr
 	switch treeID {
 	case btrfsprim.ROOT_TREE_OBJECTID:
-		sb, _ := ts.inner.Superblock()
+		sb, _ := ts.Superblock()
 		root = sb.RootTree
 	case btrfsprim.CHUNK_TREE_OBJECTID:
-		sb, _ := ts.inner.Superblock()
+		sb, _ := ts.Superblock()
 		root = sb.ChunkTree
 	case btrfsprim.TREE_LOG_OBJECTID:
-		sb, _ := ts.inner.Superblock()
+		sb, _ := ts.Superblock()
 		root = sb.LogTree
 	case btrfsprim.BLOCK_GROUP_TREE_OBJECTID:
-		sb, _ := ts.inner.Superblock()
+		sb, _ := ts.Superblock()
 		root = sb.BlockGroupRoot
 	default:
 		rootOff, rootItem, ok := ts.cb.LookupRoot(ctx, treeID)
diff --git a/lib/btrfsutil/rebuilt_readitem.go b/lib/btrfsutil/rebuilt_readitem.go
index e5faa45..841b04a 100644
--- a/lib/btrfsutil/rebuilt_readitem.go
+++ b/lib/btrfsutil/rebuilt_readitem.go
@@ -35,7 +35,7 @@ func (ts *RebuiltForrest) readItem(ctx context.Context, ptr ItemPtr) btrfstree.I
 		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for negative item slot: %v", ptr.Slot))
 	}
 
-	node, err := ts.inner.AcquireNode(ctx, ptr.Node, btrfstree.NodeExpectations{
+	node, err := ts.AcquireNode(ctx, ptr.Node, btrfstree.NodeExpectations{
 		LAddr:      containers.OptionalValue(ptr.Node),
 		Level:      containers.OptionalValue(graphInfo.Level),
 		Generation: containers.OptionalValue(graphInfo.Generation),
@@ -50,13 +50,12 @@ func (ts *RebuiltForrest) readItem(ctx context.Context, ptr ItemPtr) btrfstree.I
 		MinItem: containers.OptionalValue(graphInfo.MinItem(ts.graph)),
 		MaxItem: containers.OptionalValue(graphInfo.MaxItem(ts.graph)),
 	})
-	defer ts.inner.ReleaseNode(node)
+	defer ts.ReleaseNode(node)
 	if err != nil {
 		panic(fmt.Errorf("should not happen: i/o error: %w", err))
 	}
 
 	items := node.BodyLeaf
-
 	if ptr.Slot >= len(items) {
 		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for out-of-bounds item slot: slot=%v len=%v",
 			ptr.Slot, len(items)))
diff --git a/lib/btrfsutil/rebuilt_tree.go b/lib/btrfsutil/rebuilt_tree.go
index 9ab0356..0844511 100644
--- a/lib/btrfsutil/rebuilt_tree.go
+++ b/lib/btrfsutil/rebuilt_tree.go
@@ -478,16 +478,6 @@ func (tree *RebuiltTree) RebuiltCOWDistance(parentID btrfsprim.ObjID) (dist int,
 	}
 }
 
-// ReadItem reads an item from a tree.
-func (tree *RebuiltTree) ReadItem(ctx context.Context, key btrfsprim.Key) btrfsitem.Item {
-	ptr, ok := tree.RebuiltAcquireItems(ctx).Load(key)
-	tree.RebuiltReleaseItems()
-	if !ok {
-		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltTree.ReadItem called for not-included key: %v", key))
-	}
-	return tree.forrest.readItem(ctx, ptr).Body
-}
-
 // RebuiltLeafToRoots returns the list of potential roots (to pass to
 // .RebuiltAddRoot) that include a given leaf-node.
 func (tree *RebuiltTree) RebuiltLeafToRoots(ctx context.Context, leaf btrfsvol.LogicalAddr) containers.Set[btrfsvol.LogicalAddr] {