Merge branch 'lukeshu/misc'

6 files changed, 110 insertions, 105 deletions

diff --git a/lib/btrfsutil/graph.go b/lib/btrfsutil/graph.go
index 8debe9d..09a17b4 100644
--- a/lib/btrfsutil/graph.go
+++ b/lib/btrfsutil/graph.go
@@ -27,20 +27,31 @@ type GraphNode struct {
 	Level      uint8
 	Generation btrfsprim.Generation
 	Owner      btrfsprim.ObjID
-	NumItems   uint32
-	MinItem    btrfsprim.Key
-	MaxItem    btrfsprim.Key
 	Items      []btrfsprim.Key
 }
 
+func (n GraphNode) MinItem() btrfsprim.Key {
+	if len(n.Items) == 0 {
+		return btrfsprim.Key{}
+	}
+	return n.Items[0]
+}
+
+func (n GraphNode) MaxItem() btrfsprim.Key {
+	if len(n.Items) == 0 {
+		return btrfsprim.Key{}
+	}
+	return n.Items[len(n.Items)-1]
+}
+
 func (n GraphNode) String() string {
 	if reflect.ValueOf(n).IsZero() {
 		return "{}"
 	}
 	return fmt.Sprintf(`{lvl:%v, gen:%v, tree:%v, cnt:%v, min:(%v,%v,%v), max:(%v,%v,%v)}`,
-		n.Level, n.Generation, n.Owner, n.NumItems,
-		n.MinItem.ObjectID, n.MinItem.ItemType, n.MinItem.Offset,
-		n.MaxItem.ObjectID, n.MaxItem.ItemType, n.MaxItem.Offset)
+		n.Level, n.Generation, n.Owner, len(n.Items),
+		n.MinItem().ObjectID, n.MinItem().ItemType, n.MinItem().Offset,
+		n.MaxItem().ObjectID, n.MaxItem().ItemType, n.MaxItem().Offset)
 }
 
 type GraphEdge struct {
@@ -143,9 +154,6 @@ func (g Graph) InsertNode(nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.No
 		Level:      nodeRef.Data.Head.Level,
 		Generation: nodeRef.Data.Head.Generation,
 		Owner:      nodeRef.Data.Head.Owner,
-		NumItems:   nodeRef.Data.Head.NumItems,
-		MinItem:    discardOK(nodeRef.Data.MinItem()),
-		MaxItem:    discardOK(nodeRef.Data.MaxItem()),
 	}
 
 	if nodeRef.Data.Head.Level == 0 {
@@ -175,8 +183,8 @@ func (g Graph) InsertNode(nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.No
 		}
 	} else {
 		g.Nodes[nodeRef.Addr] = nodeData
-		kps := make([]GraphEdge, len(nodeRef.Data.BodyInternal))
-		for i, kp := range nodeRef.Data.BodyInternal {
+		kps := make([]GraphEdge, len(nodeRef.Data.BodyInterior))
+		for i, kp := range nodeRef.Data.BodyInterior {
 			kps[i] = GraphEdge{
 				FromNode:     nodeRef.Addr,
 				FromItem:     i,
@@ -256,7 +264,3 @@ func (g Graph) FinalCheck(ctx context.Context, fs diskio.File[btrfsvol.LogicalAd
 
 	return nil
 }
-
-func discardOK[T any](val T, _ bool) T {
-	return val
-}
diff --git a/lib/btrfsutil/graph_loops.go b/lib/btrfsutil/graph_loops.go
index 3382705..b5690af 100644
--- a/lib/btrfsutil/graph_loops.go
+++ b/lib/btrfsutil/graph_loops.go
@@ -22,15 +22,15 @@ func (g Graph) renderNode(node btrfsvol.LogicalAddr) []string {
 			fmt.Sprintf("{addr:      %v,", node),
 			fmt.Sprintf(" level:     %v,", nodeData.Level),
 			fmt.Sprintf(" gen:       %v,", nodeData.Generation),
-			fmt.Sprintf(" num_items: %v,", nodeData.NumItems),
+			fmt.Sprintf(" num_items: %v,", len(nodeData.Items)),
 			fmt.Sprintf(" min_item:  {%d,%v,%d},",
-				nodeData.MinItem.ObjectID,
-				nodeData.MinItem.ItemType,
-				nodeData.MinItem.Offset),
+				nodeData.MinItem().ObjectID,
+				nodeData.MinItem().ItemType,
+				nodeData.MinItem().Offset),
 			fmt.Sprintf(" max_item:  {%d,%v,%d}}",
-				nodeData.MaxItem.ObjectID,
-				nodeData.MaxItem.ItemType,
-				nodeData.MaxItem.Offset),
+				nodeData.MaxItem().ObjectID,
+				nodeData.MaxItem().ItemType,
+				nodeData.MaxItem().Offset),
 		}
 	} else if nodeErr, ok := g.BadNodes[node]; ok {
 		return []string{
@@ -120,11 +120,12 @@ func checkNodeExpectations(kp GraphEdge, toNode GraphNode) error {
 		errs = append(errs, fmt.Errorf("kp.generation=%v != node.generation=%v",
 			kp.ToGeneration, toNode.Generation))
 	}
-	if toNode.NumItems == 0 {
+	switch {
+	case len(toNode.Items) == 0:
 		errs = append(errs, fmt.Errorf("node.num_items=0"))
-	} else if kp.ToKey != (btrfsprim.Key{}) && toNode.MinItem != kp.ToKey {
+	case kp.ToKey != (btrfsprim.Key{}) && toNode.MinItem() != kp.ToKey:
 		errs = append(errs, fmt.Errorf("kp.key=%v != node.items[0].key=%v",
-			kp.ToKey, toNode.MinItem))
+			kp.ToKey, toNode.MinItem()))
 	}
 	if len(errs) > 0 {
 		return errs
diff --git a/lib/btrfsutil/old_rebuilt_forrest.go b/lib/btrfsutil/old_rebuilt_forrest.go
index 2386803..af2643a 100644
--- a/lib/btrfsutil/old_rebuilt_forrest.go
+++ b/lib/btrfsutil/old_rebuilt_forrest.go
@@ -153,40 +153,39 @@ func (bt *OldRebuiltForrest) RebuiltTree(treeID btrfsprim.ObjID) oldRebuiltTree
 }
 
 func (bt *OldRebuiltForrest) rawTreeWalk(root btrfstree.TreeRoot, cacheEntry oldRebuiltTree, walked *[]btrfsprim.Key) {
-	btrfstree.TreeOperatorImpl{NodeSource: bt.inner}.RawTreeWalk(
-		bt.ctx,
-		root,
-		func(err *btrfstree.TreeError) {
-			if len(err.Path) > 0 && err.Path.Node(-1).ToNodeAddr == 0 {
-				// This is a panic because on the filesystems I'm working with it more likely
-				// indicates a bug in my item parser than a problem with the filesystem.
-				panic(fmt.Errorf("TODO: error parsing item: %w", err))
+	errHandle := func(err *btrfstree.TreeError) {
+		if len(err.Path) > 0 && err.Path.Node(-1).ToNodeAddr == 0 {
+			// This is a panic because on the filesystems I'm working with it more likely
+			// indicates a bug in my item parser than a problem with the filesystem.
+			panic(fmt.Errorf("TODO: error parsing item: %w", err))
+		}
+		cacheEntry.Errors.Insert(oldRebuiltTreeError{
+			Path: bt.arena.Deflate(err.Path),
+			Err:  err.Err,
+		})
+	}
+
+	cbs := btrfstree.TreeWalkHandler{
+		Item: func(path btrfstree.TreePath, item btrfstree.Item) error {
+			if cacheEntry.Items.Search(func(v oldRebuiltTreeValue) int { return item.Key.Compare(v.Key) }) != nil {
+				// This is a panic because I'm not really sure what the best way to
+				// handle this is, and so if this happens I want the program to crash
+				// and force me to figure out how to handle it.
+				panic(fmt.Errorf("dup key=%v in tree=%v", item.Key, root.TreeID))
 			}
-			cacheEntry.Errors.Insert(oldRebuiltTreeError{
-				Path: bt.arena.Deflate(err.Path),
-				Err:  err.Err,
+			cacheEntry.Items.Insert(oldRebuiltTreeValue{
+				Path:     bt.arena.Deflate(path),
+				Key:      item.Key,
+				ItemSize: item.BodySize,
 			})
+			if walked != nil {
+				*walked = append(*walked, item.Key)
+			}
+			return nil
 		},
-		btrfstree.TreeWalkHandler{
-			Item: func(path btrfstree.TreePath, item btrfstree.Item) error {
-				if cacheEntry.Items.Search(func(v oldRebuiltTreeValue) int { return item.Key.Compare(v.Key) }) != nil {
-					// This is a panic because I'm not really sure what the best way to
-					// handle this is, and so if this happens I want the program to crash
-					// and force me to figure out how to handle it.
-					panic(fmt.Errorf("dup key=%v in tree=%v", item.Key, root.TreeID))
-				}
-				cacheEntry.Items.Insert(oldRebuiltTreeValue{
-					Path:     bt.arena.Deflate(path),
-					Key:      item.Key,
-					ItemSize: item.BodySize,
-				})
-				if walked != nil {
-					*walked = append(*walked, item.Key)
-				}
-				return nil
-			},
-		},
-	)
+	}
+
+	btrfstree.TreeOperatorImpl{NodeSource: bt.inner}.RawTreeWalk(bt.ctx, root, errHandle, cbs)
 }
 
 func (bt *OldRebuiltForrest) TreeLookup(treeID btrfsprim.ObjID, key btrfsprim.Key) (btrfstree.Item, error) {
@@ -237,7 +236,7 @@ func (bt *OldRebuiltForrest) TreeSearch(treeID btrfsprim.ObjID, fn func(btrfspri
 		return btrfstree.Item{}, bt.addErrs(tree, fn, err)
 	}
 
-	item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemIdx]
+	item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemSlot]
 	item.Body = item.Body.CloneItem()
 
 	// Since we were only asked to return 1 item, it isn't
@@ -275,7 +274,7 @@ func (bt *OldRebuiltForrest) TreeSearchAll(treeID btrfsprim.ObjID, fn func(btrfs
 				return nil, bt.addErrs(tree, fn, err)
 			}
 		}
-		ret[i] = node.Data.BodyLeaf[itemPath.Node(-1).FromItemIdx]
+		ret[i] = node.Data.BodyLeaf[itemPath.Node(-1).FromItemSlot]
 		ret[i].Body = ret[i].Body.CloneItem()
 	}
 	btrfstree.FreeNodeRef(node)
@@ -295,6 +294,9 @@ func (bt *OldRebuiltForrest) TreeWalk(ctx context.Context, treeID btrfsprim.ObjI
 		})
 		return
 	}
+	if cbs.Item == nil {
+		return
+	}
 	var node *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]
 	tree.Items.Range(func(indexItem *containers.RBNode[oldRebuiltTreeValue]) bool {
 		if ctx.Err() != nil {
@@ -303,23 +305,21 @@ func (bt *OldRebuiltForrest) TreeWalk(ctx context.Context, treeID btrfsprim.ObjI
 		if bt.ctx.Err() != nil {
 			return false
 		}
-		if cbs.Item != nil {
-			itemPath := bt.arena.Inflate(indexItem.Value.Path)
-			if node == nil || node.Addr != itemPath.Node(-2).ToNodeAddr {
-				var err error
+		itemPath := bt.arena.Inflate(indexItem.Value.Path)
+		if node == nil || node.Addr != itemPath.Node(-2).ToNodeAddr {
+			var err error
+			btrfstree.FreeNodeRef(node)
+			node, err = bt.inner.ReadNode(itemPath.Parent())
+			if err != nil {
 				btrfstree.FreeNodeRef(node)
-				node, err = bt.inner.ReadNode(itemPath.Parent())
-				if err != nil {
-					btrfstree.FreeNodeRef(node)
-					errHandle(&btrfstree.TreeError{Path: itemPath, Err: err})
-					return true
-				}
-			}
-			item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemIdx]
-			if err := cbs.Item(itemPath, item); err != nil {
 				errHandle(&btrfstree.TreeError{Path: itemPath, Err: err})
+				return true
 			}
 		}
+		item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemSlot]
+		if err := cbs.Item(itemPath, item); err != nil {
+			errHandle(&btrfstree.TreeError{Path: itemPath, Err: err})
+		}
 		return true
 	})
 	btrfstree.FreeNodeRef(node)
diff --git a/lib/btrfsutil/rebuilt_readitem.go b/lib/btrfsutil/rebuilt_readitem.go
index 57440cf..016299c 100644
--- a/lib/btrfsutil/rebuilt_readitem.go
+++ b/lib/btrfsutil/rebuilt_readitem.go
@@ -22,11 +22,11 @@ import (
 
 type ItemPtr struct {
 	Node btrfsvol.LogicalAddr
-	Idx  int
+	Slot int
 }
 
 func (ptr ItemPtr) String() string {
-	return fmt.Sprintf("node@%v[%v]", ptr.Node, ptr.Idx)
+	return fmt.Sprintf("node@%v[%v]", ptr.Node, ptr.Slot)
 }
 
 type SizeAndErr struct {
@@ -74,7 +74,7 @@ func (o *KeyIO) InsertNode(nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.N
 	for i, item := range nodeRef.Data.BodyLeaf {
 		ptr := ItemPtr{
 			Node: nodeRef.Addr,
-			Idx:  i,
+			Slot: i,
 		}
 		switch itemBody := item.Body.(type) {
 		case *btrfsitem.Inode:
@@ -141,8 +141,8 @@ func (o *KeyIO) readNode(ctx context.Context, laddr btrfsvol.LogicalAddr) *diski
 			}
 			return nil
 		},
-		MinItem: containers.Optional[btrfsprim.Key]{OK: true, Val: graphInfo.MinItem},
-		MaxItem: containers.Optional[btrfsprim.Key]{OK: true, Val: graphInfo.MaxItem},
+		MinItem: containers.Optional[btrfsprim.Key]{OK: true, Val: graphInfo.MinItem()},
+		MaxItem: containers.Optional[btrfsprim.Key]{OK: true, Val: graphInfo.MaxItem()},
 	})
 	if err != nil {
 		panic(fmt.Errorf("should not happen: i/o error: %w", err))
@@ -159,13 +159,13 @@ func (o *KeyIO) ReadItem(ctx context.Context, ptr ItemPtr) btrfsitem.Item {
 	if o.graph.Nodes[ptr.Node].Level != 0 {
 		panic(fmt.Errorf("should not happen: btrfsutil.KeyIO.ReadItem called for non-leaf node@%v", ptr.Node))
 	}
-	if ptr.Idx < 0 {
-		panic(fmt.Errorf("should not happen: btrfsutil.KeyIO.ReadItem called for negative item index: %v", ptr.Idx))
+	if ptr.Slot < 0 {
+		panic(fmt.Errorf("should not happen: btrfsutil.KeyIO.ReadItem called for negative item slot: %v", ptr.Slot))
 	}
 	items := o.readNode(ctx, ptr.Node).Data.BodyLeaf
-	if ptr.Idx >= len(items) {
-		panic(fmt.Errorf("should not happen: btrfsutil.KeyIO.ReadItem called for out-of-bounds item index: index=%v len=%v",
-			ptr.Idx, len(items)))
+	if ptr.Slot >= len(items) {
+		panic(fmt.Errorf("should not happen: btrfsutil.KeyIO.ReadItem called for out-of-bounds item slot: slot=%v len=%v",
+			ptr.Slot, len(items)))
 	}
-	return items[ptr.Idx].Body.CloneItem()
+	return items[ptr.Slot].Body.CloneItem()
 }
diff --git a/lib/btrfsutil/rebuilt_tree.go b/lib/btrfsutil/rebuilt_tree.go
index 1009204..3133a9e 100644
--- a/lib/btrfsutil/rebuilt_tree.go
+++ b/lib/btrfsutil/rebuilt_tree.go
@@ -33,7 +33,7 @@ type RebuiltTree struct {
 	mu    sync.RWMutex
 	Roots containers.Set[btrfsvol.LogicalAddr]
 	// There are 3 more mutable "members" that are protected by
-	// `mu`; but they live in a shared LRUcache.  They are all
+	// `mu`; but they live in a shared ARCache.  They are all
 	// derived from tree.Roots, which is why it's OK if they get
 	// evicted.
 	//
@@ -42,7 +42,7 @@ type RebuiltTree struct {
 	//  3. tree.PotentialItems() = tree.forrest.excItems.Load(tree.ID)
 }
 
-// LRU member 1: .leafToRoots() ////////////////////////////////////////////////////////////////////////////////////////
+// evictable member 1: .leafToRoots() //////////////////////////////////////////////////////////////////////////////////
 
 // leafToRoots returns all leafs (lvl=0) in the filesystem that pass
 // .isOwnerOK, whether or not they're in the tree.
@@ -129,7 +129,7 @@ func (tree *RebuiltTree) isOwnerOK(owner btrfsprim.ObjID, gen btrfsprim.Generati
 	}
 }
 
-// LRU members 2 and 3: .Items() and .PotentialItems() /////////////////////////////////////////////////////////////////
+// evictable members 2 and 3: .Items() and .PotentialItems() ///////////////////////////////////////////////////////////
 
 // Items returns a map of the items contained in this tree.
 //
@@ -192,7 +192,7 @@ func (tree *RebuiltTree) items(ctx context.Context, cache containers.Map[btrfspr
 			for j, itemKey := range tree.forrest.graph.Nodes[leaf].Items {
 				newPtr := ItemPtr{
 					Node: leaf,
-					Idx:  j,
+					Slot: j,
 				}
 				if oldPtr, exists := index.Load(itemKey); !exists {
 					index.Store(itemKey, newPtr)
diff --git a/lib/btrfsutil/skinny_paths.go b/lib/btrfsutil/skinny_paths.go
index 1695990..adf539b 100644
--- a/lib/btrfsutil/skinny_paths.go
+++ b/lib/btrfsutil/skinny_paths.go
@@ -39,8 +39,8 @@ func (a *SkinnyPathArena) init() {
 	}
 }
 
-func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemIdx int) (btrfstree.TreePathElem, error) {
-	if itemIdx < 0 {
+func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemSlot int) (btrfstree.TreePathElem, error) {
+	if itemSlot < 0 {
 		panic("should not happen")
 	}
 
@@ -48,7 +48,7 @@ func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemIdx int) (btrfs
 
 	ret, ok := a.fatItems.Load(skinnyItem{
 		Node: parent.Node(-1).ToNodeAddr,
-		Item: itemIdx,
+		Item: itemSlot,
 	})
 	if ok {
 		return ret, nil
@@ -60,17 +60,17 @@ func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemIdx int) (btrfs
 		return btrfstree.TreePathElem{}, err
 	}
 	if node.Data.Head.Level > 0 {
-		if itemIdx >= len(node.Data.BodyInternal) {
+		if itemSlot >= len(node.Data.BodyInterior) {
 			panic("should not happen")
 		}
-		for i, item := range node.Data.BodyInternal {
+		for i, item := range node.Data.BodyInterior {
 			toMaxKey := parent.Node(-1).ToMaxKey
-			if i+1 < len(node.Data.BodyInternal) {
-				toMaxKey = node.Data.BodyInternal[i+1].Key.Mm()
+			if i+1 < len(node.Data.BodyInterior) {
+				toMaxKey = node.Data.BodyInterior[i+1].Key.Mm()
 			}
 			elem := btrfstree.TreePathElem{
 				FromTree:         node.Data.Head.Owner,
-				FromItemIdx:      i,
+				FromItemSlot:     i,
 				ToNodeAddr:       item.BlockPtr,
 				ToNodeGeneration: item.Generation,
 				ToNodeLevel:      node.Data.Head.Level - 1,
@@ -78,23 +78,23 @@ func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemIdx int) (btrfs
 				ToMaxKey:         toMaxKey,
 			}
 			a.fatItems.Store(skinnyItem{Node: parent.Node(-1).ToNodeAddr, Item: i}, elem)
-			if i == itemIdx {
+			if i == itemSlot {
 				ret = elem
 			}
 		}
 	} else {
-		if itemIdx >= len(node.Data.BodyLeaf) {
+		if itemSlot >= len(node.Data.BodyLeaf) {
 			panic("should not happen")
 		}
 		for i, item := range node.Data.BodyLeaf {
 			elem := btrfstree.TreePathElem{
-				FromTree:    node.Data.Head.Owner,
-				FromItemIdx: i,
-				ToKey:       item.Key,
-				ToMaxKey:    item.Key,
+				FromTree:     node.Data.Head.Owner,
+				FromItemSlot: i,
+				ToKey:        item.Key,
+				ToMaxKey:     item.Key,
 			}
 			a.fatItems.Store(skinnyItem{Node: parent.Node(-1).ToNodeAddr, Item: i}, elem)
-			if i == itemIdx {
+			if i == itemSlot {
 				ret = elem
 			}
 		}
@@ -114,8 +114,8 @@ func (a *SkinnyPathArena) Deflate(fat btrfstree.TreePath) SkinnyPath {
 			a.fatRoots[elem.ToNodeAddr] = elem
 			ret.Root = elem.ToNodeAddr
 		} else {
-			a.fatItems.Store(skinnyItem{Node: prevNode, Item: elem.FromItemIdx}, elem)
-			ret.Items = append(ret.Items, elem.FromItemIdx)
+			a.fatItems.Store(skinnyItem{Node: prevNode, Item: elem.FromItemSlot}, elem)
+			ret.Items = append(ret.Items, elem.FromItemSlot)
 		}
 		prevNode = elem.ToNodeAddr
 	}
@@ -134,8 +134,8 @@ func (a *SkinnyPathArena) Inflate(skinny SkinnyPath) btrfstree.TreePath {
 	}
 	ret = append(ret, root)
 
-	for _, itemIdx := range skinny.Items {
-		elem, err := a.getItem(ret, itemIdx)
+	for _, itemSlot := range skinny.Items {
+		elem, err := a.getItem(ret, itemSlot)
 		if err != nil {
 			panic(err)
 		}