tree-wide: Refer to item "slots" rather than "indexes"

7 files changed, 74 insertions, 74 deletions

diff --git a/cmd/btrfs-rec/inspect/dumptrees/print_tree.go b/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
index b7e7552..a0a3d46 100644
--- a/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
+++ b/cmd/btrfs-rec/inspect/dumptrees/print_tree.go
@@ -113,7 +113,7 @@ func printTree(ctx context.Context, out io.Writer, fs *btrfs.FS, treeID btrfspri
 		},
 		Item: func(path btrfstree.TreePath, item btrfstree.Item) error {
 			treeID := path[0].FromTree
-			i := path.Node(-1).FromItemIdx
+			i := path.Node(-1).FromItemSlot
 			bs, _ := binstruct.Marshal(item.Body)
 			itemSize := uint32(len(bs))
 			itemOffset -= itemSize
diff --git a/lib/btrfs/btrfstree/btree_tree.go b/lib/btrfs/btrfstree/btree_tree.go
index f88dd44..e75eb0b 100644
--- a/lib/btrfs/btrfstree/btree_tree.go
+++ b/lib/btrfs/btrfstree/btree_tree.go
@@ -115,7 +115,7 @@ func (fs TreeOperatorImpl) TreeWalk(ctx context.Context, treeID btrfsprim.ObjID,
 func (fs TreeOperatorImpl) RawTreeWalk(ctx context.Context, rootInfo TreeRoot, errHandle func(*TreeError), cbs TreeWalkHandler) {
 	path := TreePath{{
 		FromTree:         rootInfo.TreeID,
-		FromItemIdx:      -1,
+		FromItemSlot:     -1,
 		ToNodeAddr:       rootInfo.RootNode,
 		ToNodeGeneration: rootInfo.Generation,
 		ToNodeLevel:      rootInfo.Level,
@@ -176,7 +176,7 @@ func (fs TreeOperatorImpl) treeWalk(ctx context.Context, path TreePath, errHandl
 			}
 			itemPath := append(path, TreePathElem{
 				FromTree:         node.Data.Head.Owner,
-				FromItemIdx:      i,
+				FromItemSlot:     i,
 				ToNodeAddr:       item.BlockPtr,
 				ToNodeGeneration: item.Generation,
 				ToNodeLevel:      node.Data.Head.Level - 1,
@@ -203,10 +203,10 @@ func (fs TreeOperatorImpl) treeWalk(ctx context.Context, path TreePath, errHandl
 		}
 		for i, item := range node.Data.BodyLeaf {
 			itemPath := append(path, 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,
 			})
 			if errBody, isErr := item.Body.(*btrfsitem.Error); isErr {
 				if cbs.BadItem == nil {
@@ -244,7 +244,7 @@ func (fs TreeOperatorImpl) treeWalk(ctx context.Context, path TreePath, errHandl
 func (fs TreeOperatorImpl) treeSearch(treeRoot TreeRoot, fn func(btrfsprim.Key, uint32) int) (TreePath, *diskio.Ref[btrfsvol.LogicalAddr, Node], error) {
 	path := TreePath{{
 		FromTree:         treeRoot.TreeID,
-		FromItemIdx:      -1,
+		FromItemSlot:     -1,
 		ToNodeAddr:       treeRoot.RootNode,
 		ToNodeGeneration: treeRoot.Generation,
 		ToNodeLevel:      treeRoot.Level,
@@ -284,7 +284,7 @@ func (fs TreeOperatorImpl) treeSearch(treeRoot TreeRoot, fn func(btrfsprim.Key,
 			}
 			path = append(path, TreePathElem{
 				FromTree:         node.Data.Head.Owner,
-				FromItemIdx:      lastGood,
+				FromItemSlot:     lastGood,
 				ToNodeAddr:       node.Data.BodyInterior[lastGood].BlockPtr,
 				ToNodeGeneration: node.Data.BodyInterior[lastGood].Generation,
 				ToNodeLevel:      node.Data.Head.Level - 1,
@@ -305,7 +305,7 @@ func (fs TreeOperatorImpl) treeSearch(treeRoot TreeRoot, fn func(btrfsprim.Key,
 			// is returned.
 			//
 			// Implement this search as a binary search.
-			idx, ok := slices.Search(node.Data.BodyLeaf, func(item Item) int {
+			slot, ok := slices.Search(node.Data.BodyLeaf, func(item Item) int {
 				return fn(item.Key, item.BodySize)
 			})
 			if !ok {
@@ -313,10 +313,10 @@ func (fs TreeOperatorImpl) treeSearch(treeRoot TreeRoot, fn func(btrfsprim.Key,
 				return nil, nil, iofs.ErrNotExist
 			}
 			path = append(path, TreePathElem{
-				FromTree:    node.Data.Head.Owner,
-				FromItemIdx: idx,
-				ToKey:       node.Data.BodyLeaf[idx].Key,
-				ToMaxKey:    node.Data.BodyLeaf[idx].Key,
+				FromTree:     node.Data.Head.Owner,
+				FromItemSlot: slot,
+				ToKey:        node.Data.BodyLeaf[slot].Key,
+				ToMaxKey:     node.Data.BodyLeaf[slot].Key,
 			})
 			return path, node, nil
 		}
@@ -328,14 +328,14 @@ func (fs TreeOperatorImpl) prev(path TreePath, node *diskio.Ref[btrfsvol.Logical
 	path = path.DeepCopy()
 
 	// go up
-	for path.Node(-1).FromItemIdx < 1 {
+	for path.Node(-1).FromItemSlot < 1 {
 		path = path.Parent()
 		if len(path) == 0 {
 			return nil, nil, nil
 		}
 	}
 	// go left
-	path.Node(-1).FromItemIdx--
+	path.Node(-1).FromItemSlot--
 	if path.Node(-1).ToNodeAddr != 0 {
 		if node.Addr != path.Node(-2).ToNodeAddr {
 			FreeNodeRef(node)
@@ -344,7 +344,7 @@ func (fs TreeOperatorImpl) prev(path TreePath, node *diskio.Ref[btrfsvol.Logical
 				FreeNodeRef(node)
 				return nil, nil, err
 			}
-			path.Node(-1).ToNodeAddr = node.Data.BodyInterior[path.Node(-1).FromItemIdx].BlockPtr
+			path.Node(-1).ToNodeAddr = node.Data.BodyInterior[path.Node(-1).FromItemSlot].BlockPtr
 		}
 	}
 	// go down
@@ -360,7 +360,7 @@ func (fs TreeOperatorImpl) prev(path TreePath, node *diskio.Ref[btrfsvol.Logical
 		if node.Data.Head.Level > 0 {
 			path = append(path, TreePathElem{
 				FromTree:         node.Data.Head.Owner,
-				FromItemIdx:      len(node.Data.BodyInterior) - 1,
+				FromItemSlot:     len(node.Data.BodyInterior) - 1,
 				ToNodeAddr:       node.Data.BodyInterior[len(node.Data.BodyInterior)-1].BlockPtr,
 				ToNodeGeneration: node.Data.BodyInterior[len(node.Data.BodyInterior)-1].Generation,
 				ToNodeLevel:      node.Data.Head.Level - 1,
@@ -369,10 +369,10 @@ func (fs TreeOperatorImpl) prev(path TreePath, node *diskio.Ref[btrfsvol.Logical
 			})
 		} else {
 			path = append(path, TreePathElem{
-				FromTree:    node.Data.Head.Owner,
-				FromItemIdx: len(node.Data.BodyLeaf) - 1,
-				ToKey:       node.Data.BodyLeaf[len(node.Data.BodyLeaf)-1].Key,
-				ToMaxKey:    node.Data.BodyLeaf[len(node.Data.BodyLeaf)-1].Key,
+				FromTree:     node.Data.Head.Owner,
+				FromItemSlot: len(node.Data.BodyLeaf) - 1,
+				ToKey:        node.Data.BodyLeaf[len(node.Data.BodyLeaf)-1].Key,
+				ToMaxKey:     node.Data.BodyLeaf[len(node.Data.BodyLeaf)-1].Key,
 			})
 		}
 	}
@@ -402,7 +402,7 @@ func (fs TreeOperatorImpl) next(path TreePath, node *diskio.Ref[btrfsvol.Logical
 		}
 		path.Node(-2).ToNodeLevel = node.Data.Head.Level
 	}
-	for path.Node(-1).FromItemIdx+1 >= int(node.Data.Head.NumItems) {
+	for path.Node(-1).FromItemSlot+1 >= int(node.Data.Head.NumItems) {
 		path = path.Parent()
 		if len(path) == 1 {
 			return nil, nil, nil
@@ -418,7 +418,7 @@ func (fs TreeOperatorImpl) next(path TreePath, node *diskio.Ref[btrfsvol.Logical
 		}
 	}
 	// go right
-	path.Node(-1).FromItemIdx++
+	path.Node(-1).FromItemSlot++
 	if path.Node(-1).ToNodeAddr != 0 {
 		if node.Addr != path.Node(-2).ToNodeAddr {
 			FreeNodeRef(node)
@@ -427,7 +427,7 @@ func (fs TreeOperatorImpl) next(path TreePath, node *diskio.Ref[btrfsvol.Logical
 				FreeNodeRef(node)
 				return nil, nil, err
 			}
-			path.Node(-1).ToNodeAddr = node.Data.BodyInterior[path.Node(-1).FromItemIdx].BlockPtr
+			path.Node(-1).ToNodeAddr = node.Data.BodyInterior[path.Node(-1).FromItemSlot].BlockPtr
 		}
 	}
 	// go down
@@ -448,7 +448,7 @@ func (fs TreeOperatorImpl) next(path TreePath, node *diskio.Ref[btrfsvol.Logical
 			}
 			path = append(path, TreePathElem{
 				FromTree:         node.Data.Head.Owner,
-				FromItemIdx:      0,
+				FromItemSlot:     0,
 				ToNodeAddr:       node.Data.BodyInterior[0].BlockPtr,
 				ToNodeGeneration: node.Data.BodyInterior[0].Generation,
 				ToNodeLevel:      node.Data.Head.Level - 1,
@@ -457,10 +457,10 @@ func (fs TreeOperatorImpl) next(path TreePath, node *diskio.Ref[btrfsvol.Logical
 			})
 		} else {
 			path = append(path, TreePathElem{
-				FromTree:    node.Data.Head.Owner,
-				FromItemIdx: 0,
-				ToKey:       node.Data.BodyInterior[0].Key,
-				ToMaxKey:    node.Data.BodyInterior[0].Key,
+				FromTree:     node.Data.Head.Owner,
+				FromItemSlot: 0,
+				ToKey:        node.Data.BodyInterior[0].Key,
+				ToMaxKey:     node.Data.BodyInterior[0].Key,
 			})
 		}
 	}
@@ -490,7 +490,7 @@ func (fs TreeOperatorImpl) TreeSearch(treeID btrfsprim.ObjID, fn func(btrfsprim.
 	if err != nil {
 		return Item{}, err
 	}
-	item := node.Data.BodyLeaf[path.Node(-1).FromItemIdx]
+	item := node.Data.BodyLeaf[path.Node(-1).FromItemSlot]
 	item.Body = item.Body.CloneItem()
 	FreeNodeRef(node)
 	return item, nil
@@ -526,7 +526,7 @@ func (fs TreeOperatorImpl) TreeSearchAll(treeID btrfsprim.ObjID, fn func(btrfspr
 	if err != nil {
 		return nil, err
 	}
-	middleItem := middleNode.Data.BodyLeaf[middlePath.Node(-1).FromItemIdx]
+	middleItem := middleNode.Data.BodyLeaf[middlePath.Node(-1).FromItemSlot]
 
 	ret := []Item{middleItem}
 	var errs derror.MultiError
@@ -540,7 +540,7 @@ func (fs TreeOperatorImpl) TreeSearchAll(treeID btrfsprim.ObjID, fn func(btrfspr
 		if len(prevPath) == 0 {
 			break
 		}
-		prevItem := prevNode.Data.BodyLeaf[prevPath.Node(-1).FromItemIdx]
+		prevItem := prevNode.Data.BodyLeaf[prevPath.Node(-1).FromItemSlot]
 		if fn(prevItem.Key, prevItem.BodySize) != 0 {
 			break
 		}
@@ -567,7 +567,7 @@ func (fs TreeOperatorImpl) TreeSearchAll(treeID btrfsprim.ObjID, fn func(btrfspr
 		if len(nextPath) == 0 {
 			break
 		}
-		nextItem := nextNode.Data.BodyLeaf[nextPath.Node(-1).FromItemIdx]
+		nextItem := nextNode.Data.BodyLeaf[nextPath.Node(-1).FromItemSlot]
 		if fn(nextItem.Key, nextItem.BodySize) != 0 {
 			break
 		}
diff --git a/lib/btrfs/btrfstree/path.go b/lib/btrfs/btrfstree/path.go
index dd2cb74..9b1a5c7 100644
--- a/lib/btrfs/btrfstree/path.go
+++ b/lib/btrfs/btrfstree/path.go
@@ -1,4 +1,4 @@
-// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -17,7 +17,7 @@ import (
 // system) to the a node or item within one of the btrees in the
 // system.
 //
-//   - The first element will always have an ItemIdx of -1.
+//   - The first element will always have an ItemSlot of -1.
 //
 //   - For .Item() callbacks, the last element will always have a
 //     NodeAddr of 0.
@@ -26,7 +26,7 @@ import (
 //
 //	[superblock: tree=B, lvl=3, gen=6]
 //	     |
-//	     | <------------------------------------------ pathElem={from_tree:B, from_idx=-1,
+//	     | <------------------------------------------ pathElem={from_tree:B, from_slot=-1,
 //	     |                                                       to_addr:0x01, to_gen=6, to_lvl=3}
 //	  +[0x01]-------------+
 //	  | lvl=3 gen=6 own=B |
@@ -34,7 +34,7 @@ import (
 //	  |0|1|2|3|4|5|6|7|8|9|
 //	  +-+-+-+-+-+-+-+-+-+-+
 //	                 |
-//	                 | <------------------------------ pathElem:{from_tree:B, from_idx:7,
+//	                 | <------------------------------ pathElem:{from_tree:B, from_slot:7,
 //	                 |                                           to_addr:0x02, to_gen:5, to_lvl:2}
 //	              +[0x02]--------------+
 //	              | lvl=2 gen=5 own=B  |
@@ -42,7 +42,7 @@ import (
 //	              |0|1|2|3|4|5|6|7|8|9|
 //	              +-+-+-+-+-+-+-+-+-+-+
 //	                           |
-//	                           | <-------------------- pathElem={from_tree:B, from_idx:6,
+//	                           | <-------------------- pathElem={from_tree:B, from_slot:6,
 //	                           |                                 to_addr:0x03, to_gen:5, to_lvl:1}
 //	                        +[0x03]-------------+
 //	                        | lvl=1 gen=5 own=A |
@@ -50,7 +50,7 @@ import (
 //	                        |0|1|2|3|4|5|6|7|8|9|
 //	                        +-+-+-+-+-+-+-+-+-+-+
 //	                               |
-//	                               | <---------------- pathElem={from_tree:A, from_idx:3,
+//	                               | <---------------- pathElem={from_tree:A, from_slot:3,
 //	                               |                             to_addr:0x04, to_gen:2, lvl:0}
 //	                             +[0x04]-------------+
 //	                             | lvl=0 gen=2 own=A |
@@ -58,7 +58,7 @@ import (
 //	                             |0|1|2|3|4|5|6|7|8|9|
 //	                             +-+-+-+-+-+-+-+-+-+-+
 //	                                |
-//	                                | <--------------- pathElem={from_tree:A, from_idx:1,
+//	                                | <--------------- pathElem={from_tree:A, from_slot:1,
 //	                                |                            to_addr:0, to_gen: 0, to_lvl:0}
 //	                              [item]
 type TreePath []TreePathElem
@@ -68,9 +68,9 @@ type TreePathElem struct {
 	// FromTree is the owning tree ID of the parent node; or the
 	// well-known tree ID if this is the root.
 	FromTree btrfsprim.ObjID
-	// FromItemIdx is the index of this KeyPointer in the parent
+	// FromItemSlot is the index of this KeyPointer in the parent
 	// Node; or -1 if this is the root and there is no KeyPointer.
-	FromItemIdx int
+	FromItemSlot int
 
 	// ToNodeAddr is the address of the node that the KeyPointer
 	// points at, or 0 if this is a leaf item and nothing is being
@@ -104,13 +104,13 @@ func (path TreePath) String() string {
 	} else {
 		var ret strings.Builder
 		fmt.Fprintf(&ret, "%s->", path[0].FromTree.Format(btrfsprim.ROOT_TREE_OBJECTID))
-		if len(path) == 1 && path[0] == (TreePathElem{FromTree: path[0].FromTree, FromItemIdx: -1}) {
+		if len(path) == 1 && path[0] == (TreePathElem{FromTree: path[0].FromTree, FromItemSlot: -1}) {
 			ret.WriteString("(empty-path)")
 		} else {
 			path[0].writeNodeTo(&ret)
 		}
 		for _, elem := range path[1:] {
-			fmt.Fprintf(&ret, "[%v]", elem.FromItemIdx)
+			fmt.Fprintf(&ret, "[%v]", elem.FromItemSlot)
 			if elem.ToNodeAddr != 0 {
 				ret.WriteString("->")
 				elem.writeNodeTo(&ret)
diff --git a/lib/btrfsutil/old_rebuilt_forrest.go b/lib/btrfsutil/old_rebuilt_forrest.go
index 2386803..6014793 100644
--- a/lib/btrfsutil/old_rebuilt_forrest.go
+++ b/lib/btrfsutil/old_rebuilt_forrest.go
@@ -237,7 +237,7 @@ 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 +275,7 @@ 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)
@@ -315,7 +315,7 @@ func (bt *OldRebuiltForrest) TreeWalk(ctx context.Context, treeID btrfsprim.ObjI
 					return true
 				}
 			}
-			item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemIdx]
+			item := node.Data.BodyLeaf[itemPath.Node(-1).FromItemSlot]
 			if err := cbs.Item(itemPath, item); err != nil {
 				errHandle(&btrfstree.TreeError{Path: itemPath, Err: err})
 			}
diff --git a/lib/btrfsutil/rebuilt_readitem.go b/lib/btrfsutil/rebuilt_readitem.go
index a508d99..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:
@@ -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..9e23074 100644
--- a/lib/btrfsutil/rebuilt_tree.go
+++ b/lib/btrfsutil/rebuilt_tree.go
@@ -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 da86273..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
@@ -60,7 +60,7 @@ 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.BodyInterior) {
+		if itemSlot >= len(node.Data.BodyInterior) {
 			panic("should not happen")
 		}
 		for i, item := range node.Data.BodyInterior {
@@ -70,7 +70,7 @@ func (a *SkinnyPathArena) getItem(parent btrfstree.TreePath, itemIdx int) (btrfs
 			}
 			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)
 		}