btrfstree: Change the NodeSource API so that it can do caching

3 files changed, 7 insertions, 4 deletions

diff --git a/lib/btrfs/btrfstree/btree.go b/lib/btrfs/btrfstree/btree.go
index dde485a..4f5d21b 100644
--- a/lib/btrfs/btrfstree/btree.go
+++ b/lib/btrfs/btrfstree/btree.go
@@ -97,5 +97,6 @@ func (e *TreeError) Error() string {
 
 type NodeSource interface {
 	Superblock() (*Superblock, error)
-	ReadNode(ctx context.Context, addr btrfsvol.LogicalAddr, exp NodeExpectations) (*Node, error)
+	AcquireNode(ctx context.Context, addr btrfsvol.LogicalAddr, exp NodeExpectations) (*Node, error)
+	ReleaseNode(*Node)
 }
diff --git a/lib/btrfs/btrfstree/btree_tree.go b/lib/btrfs/btrfstree/btree_tree.go
index a6311f9..86eab11 100644
--- a/lib/btrfs/btrfstree/btree_tree.go
+++ b/lib/btrfs/btrfstree/btree_tree.go
@@ -46,8 +46,8 @@ func (tree *RawTree) walk(ctx context.Context, path Path, cbs TreeWalkHandler) {
 	if !ok {
 		return
 	}
-	node, err := tree.Forrest.NodeSource.ReadNode(ctx, nodeAddr, nodeExp)
-	defer node.Free()
+	node, err := tree.Forrest.NodeSource.AcquireNode(ctx, nodeAddr, nodeExp)
+	defer tree.Forrest.NodeSource.ReleaseNode(node)
 	if ctx.Err() != nil {
 		return
 	}
diff --git a/lib/btrfs/btrfstree/types_node.go b/lib/btrfs/btrfstree/types_node.go
index 082be2c..e29431f 100644
--- a/lib/btrfs/btrfstree/types_node.go
+++ b/lib/btrfs/btrfstree/types_node.go
@@ -308,7 +308,9 @@ type ItemHeader struct {
 
 var itemPool containers.SlicePool[Item]
 
-func (node *Node) Free() {
+// RawFree is for low-level use by caches; don't use .RawFree, use
+// ReleaseNode.
+func (node *Node) RawFree() {
 	if node == nil {
 		return
 	}