Merge branch 'lukeshu/node-cache'

1 files changed, 7 insertions, 13 deletions

diff --git a/lib/btrfsutil/rebuilt_readitem.go b/lib/btrfsutil/rebuilt_readitem.go
index 03a7cdc..d3a2253 100644
--- a/lib/btrfsutil/rebuilt_readitem.go
+++ b/lib/btrfsutil/rebuilt_readitem.go
@@ -26,18 +26,14 @@ func (ptr ItemPtr) String() string {
 	return fmt.Sprintf("node@%v[%v]", ptr.Node, ptr.Slot)
 }
 
-func (ts *RebuiltForrest) readNode(ctx context.Context, laddr btrfsvol.LogicalAddr) *btrfstree.Node {
-	if cached, ok := ts.nodes.Load(laddr); ok {
-		dlog.Tracef(ctx, "cache-hit node@%v", laddr)
-		return cached
-	}
+func (ts *RebuiltForrest) readNode(ctx context.Context, laddr btrfsvol.LogicalAddr, out *btrfstree.Node) {
+	dlog.Debugf(ctx, "cache-miss node@%v, reading...", laddr)
 
 	graphInfo, ok := ts.graph.Nodes[laddr]
 	if !ok {
 		panic(fmt.Errorf("should not happen: node@%v is not mentioned in the in-memory graph", laddr))
 	}
 
-	dlog.Debugf(ctx, "cache-miss node@%v, reading...", laddr)
 	node, err := btrfstree.ReadNode[btrfsvol.LogicalAddr](ts.file, ts.sb, laddr, btrfstree.NodeExpectations{
 		LAddr:      containers.OptionalValue(laddr),
 		Level:      containers.OptionalValue(graphInfo.Level),
@@ -56,22 +52,20 @@ func (ts *RebuiltForrest) readNode(ctx context.Context, laddr btrfsvol.LogicalAd
 	if err != nil {
 		panic(fmt.Errorf("should not happen: i/o error: %w", err))
 	}
-
-	ts.nodes.Store(laddr, node)
-
-	return node
+	*out = *node
 }
 
 func (ts *RebuiltForrest) readItem(ctx context.Context, ptr ItemPtr) btrfsitem.Item {
-	ts.nodesMu.Lock()
-	defer ts.nodesMu.Unlock()
 	if ts.graph.Nodes[ptr.Node].Level != 0 {
 		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for non-leaf node@%v", ptr.Node))
 	}
 	if ptr.Slot < 0 {
 		panic(fmt.Errorf("should not happen: btrfsutil.RebuiltForrest.readItem called for negative item slot: %v", ptr.Slot))
 	}
-	items := ts.readNode(ctx, ptr.Node).BodyLeaf
+
+	items := ts.nodes.Acquire(ctx, ptr.Node).BodyLeaf
+	defer ts.nodes.Release(ptr.Node)
+
 	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)))