btrfstree: Maximum node level is 8

2 files changed, 8 insertions, 1 deletions

diff --git a/lib/btrfs/btrfstree/node_exp.go b/lib/btrfs/btrfstree/node_exp.go
index 5311ea0..dec6dbb 100644
--- a/lib/btrfs/btrfstree/node_exp.go
+++ b/lib/btrfs/btrfstree/node_exp.go
@@ -35,6 +35,10 @@ func (exp NodeExpectations) Check(node *Node) error {
 		errs = append(errs, fmt.Errorf("expected level=%v but claims to be level=%v",
 			exp.Level.Val, node.Head.Level))
 	}
+	if node.Head.Level > MaxLevel {
+		errs = append(errs, fmt.Errorf("maximum level=%v but claims to be level=%v",
+			MaxLevel, node.Head.Level))
+	}
 	if exp.Generation.OK && node.Head.Generation != exp.Generation.Val {
 		errs = append(errs, fmt.Errorf("expected generation=%v but claims to be generation=%v",
 			exp.Generation.Val, node.Head.Generation))
diff --git a/lib/btrfs/btrfstree/types_node.go b/lib/btrfs/btrfstree/types_node.go
index ed9ba58..28b93cf 100644
--- a/lib/btrfs/btrfstree/types_node.go
+++ b/lib/btrfs/btrfstree/types_node.go
@@ -103,10 +103,13 @@ type NodeHeader struct {
 	Generation    btrfsprim.Generation `bin:"off=0x50, siz=0x8"`
 	Owner         btrfsprim.ObjID      `bin:"off=0x58, siz=0x8"` // The ID of the tree that contains this node
 	NumItems      uint32               `bin:"off=0x60, siz=0x4"` // [ignored-when-writing]
-	Level         uint8                `bin:"off=0x64, siz=0x1"` // 0 for leaf nodes, >=1 for interior nodes
+	Level         uint8                `bin:"off=0x64, siz=0x1"` // 0 for leaf nodes, >=1 for interior nodes (max 8)
 	binstruct.End `bin:"off=0x65"`
 }
 
+// MaxLevel is the maximum valid NodeHeader.Level.
+const MaxLevel = 8
+
 // MaxItems returns the maximum possible valid value of
 // .Head.NumItems.
 func (node Node) MaxItems() uint32 {