Merge branch 'lukeshu/misc'

7 files changed, 104 insertions, 131 deletions

diff --git a/lib/btrfs/btrfstree/btree.go b/lib/btrfs/btrfstree/btree.go
index 25259c0..e7be281 100644
--- a/lib/btrfs/btrfstree/btree.go
+++ b/lib/btrfs/btrfstree/btree.go
@@ -21,6 +21,11 @@ type Forrest interface {
 }
 
 type Tree interface {
+	// TreeParentID returns the ID of this tree's parent and the
+	// generation that this tree was split from its parent.  If
+	// this tree has no parent, then (0, 0, nil) is returned.
+	TreeParentID(ctx context.Context) (btrfsprim.ObjID, btrfsprim.Generation, error)
+
 	// TreeLookup looks up the Item for a given key.
 	//
 	// If no such Item exists, but there is otherwise no error,
@@ -70,15 +75,6 @@ type Tree interface {
 		handleFn func(Item) bool,
 	) error
 
-	// CheckOwner returns whether it is permissible for a node
-	// with .Head.Owner=owner and .Head.Generation=gen to be in
-	// this tree.
-	//
-	// If there is an error determining this, then `failOpen`
-	// specifies whether it should return an error (false) or nil
-	// (true).
-	TreeCheckOwner(ctx context.Context, failOpen bool, owner btrfsprim.ObjID, gen btrfsprim.Generation) error
-
 	// TreeWalk is a lower-level call than TreeSubrange.  Use with
 	// hesitancy.
 	//
diff --git a/lib/btrfs/btrfstree/btree_tree.go b/lib/btrfs/btrfstree/btree_tree.go
index 7cfa257..6056ae8 100644
--- a/lib/btrfs/btrfstree/btree_tree.go
+++ b/lib/btrfs/btrfstree/btree_tree.go
@@ -38,7 +38,7 @@ func (tree *RawTree) TreeWalk(ctx context.Context, cbs TreeWalkHandler) {
 	}
 	path := Path{
 		PathRoot{
-			Tree:         tree,
+			Forrest:      tree.Forrest,
 			TreeID:       tree.ID,
 			ToAddr:       tree.RootNode,
 			ToGeneration: tree.Generation,
@@ -317,63 +317,27 @@ func (tree *RawTree) TreeSubrange(ctx context.Context, min int, searcher TreeSea
 	return nil
 }
 
-// TreeCheckOwner implements the 'Tree' interface.
-func (tree *RawTree) TreeCheckOwner(ctx context.Context, failOpen bool, owner btrfsprim.ObjID, gen btrfsprim.Generation) error {
-	var uuidTree *RawTree
-	for {
-		// Main.
-		if owner == tree.ID {
-			return nil
-		}
-		if tree.ParentUUID == (btrfsprim.UUID{}) {
-			return fmt.Errorf("owner=%v is not acceptable in this tree",
-				owner)
-		}
-		if gen > tree.ParentGen {
-			return fmt.Errorf("claimed owner=%v might be acceptable in this tree (if generation<=%v) but not with claimed generation=%v",
-				owner, tree.ParentGen, gen)
-		}
-
-		// Loop update.
-		if uuidTree == nil {
-			var err error
-			uuidTree, err = tree.Forrest.RawTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
-			if err != nil {
-				if failOpen {
-					return nil
-				}
-				return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-					owner, gen, err)
-			}
-		}
-		parentIDItem, err := uuidTree.TreeLookup(ctx, btrfsitem.UUIDToKey(tree.ParentUUID))
-		if err != nil {
-			if failOpen {
-				return nil
-			}
-			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-				owner, gen, err)
-		}
-		switch parentIDBody := parentIDItem.Body.(type) {
-		case *btrfsitem.UUIDMap:
-			tree, err = tree.Forrest.RawTree(ctx, parentIDBody.ObjID)
-			if err != nil {
-				if failOpen {
-					return nil
-				}
-				return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-					owner, gen, err)
-			}
-		case *btrfsitem.Error:
-			if failOpen {
-				return nil
-			}
-			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-				owner, gen, parentIDBody.Err)
-		default:
-			// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
-			// btrfsitem.UUIDMap or btrfsitem.Error without this code also being updated.
-			panic(fmt.Errorf("should not happen: UUID_SUBVOL item has unexpected type: %T", parentIDBody))
-		}
+// TreeParentID implements the 'Tree' interface.
+func (tree *RawTree) TreeParentID(ctx context.Context) (btrfsprim.ObjID, btrfsprim.Generation, error) {
+	if tree.ParentUUID == (btrfsprim.UUID{}) {
+		return 0, 0, nil
+	}
+	uuidTree, err := tree.Forrest.RawTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
+	if err != nil {
+		return 0, 0, err
+	}
+	parentIDItem, err := uuidTree.TreeLookup(ctx, btrfsitem.UUIDToKey(tree.ParentUUID))
+	if err != nil {
+		return 0, 0, err
+	}
+	switch parentIDBody := parentIDItem.Body.(type) {
+	case *btrfsitem.UUIDMap:
+		return parentIDBody.ObjID, tree.ParentGen, nil
+	case *btrfsitem.Error:
+		return 0, 0, parentIDBody.Err
+	default:
+		// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
+		// btrfsitem.UUIDMap or btrfsitem.Error without this code also being updated.
+		panic(fmt.Errorf("should not happen: UUID_SUBVOL item has unexpected type: %T", parentIDBody))
 	}
 }
diff --git a/lib/btrfs/btrfstree/path.go b/lib/btrfs/btrfstree/path.go
index 537df9a..57669ee 100644
--- a/lib/btrfs/btrfstree/path.go
+++ b/lib/btrfs/btrfstree/path.go
@@ -69,7 +69,7 @@ type PathElem interface {
 }
 
 type PathRoot struct {
-	Tree Tree
+	Forrest Forrest
 	// It should be no surprise that these 4 members mimic the 4
 	// members of a 'RawTree'.
 	TreeID       btrfsprim.ObjID
@@ -133,6 +133,45 @@ func (path Path) String() string {
 	return ret.String()
 }
 
+func checkOwner(
+	ctx context.Context, forrest Forrest, treeID btrfsprim.ObjID, failOpen bool,
+	ownerToCheck btrfsprim.ObjID, genToCheck btrfsprim.Generation,
+) error {
+	for {
+		if ownerToCheck == treeID {
+			return nil
+		}
+
+		tree, err := forrest.ForrestLookup(ctx, treeID)
+		if err != nil {
+			if failOpen {
+				return nil
+			}
+			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
+				ownerToCheck, genToCheck, err)
+		}
+
+		parentID, parentGen, err := tree.TreeParentID(ctx)
+		if err != nil {
+			if failOpen {
+				return nil
+			}
+			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
+				ownerToCheck, genToCheck, err)
+		}
+
+		if parentID == 0 && parentGen == 0 {
+			return fmt.Errorf("owner=%v is not acceptable in this tree",
+				ownerToCheck)
+		}
+		if genToCheck > parentGen {
+			return fmt.Errorf("claimed owner=%v might be acceptable in this tree (if generation<=%v) but not with claimed generation=%v",
+				ownerToCheck, parentGen, genToCheck)
+		}
+		treeID = parentID
+	}
+}
+
 // NodeExpectations returns the address to read and the expectations
 // to have when reading the node pointed to by this Path.
 //
@@ -153,7 +192,8 @@ func (path Path) NodeExpectations(ctx context.Context, failOpen bool) (_ btrfsvo
 			Level:      containers.OptionalValue(lastElem.ToLevel),
 			Generation: containers.OptionalValue(lastElem.ToGeneration),
 			Owner: func(owner btrfsprim.ObjID, gen btrfsprim.Generation) error {
-				return firstElem.Tree.TreeCheckOwner(ctx, failOpen, owner, gen)
+				return checkOwner(ctx, firstElem.Forrest, lastElem.TreeID, failOpen,
+					owner, gen)
 			},
 			MinItem: containers.OptionalValue(btrfsprim.Key{}),
 			MaxItem: containers.OptionalValue(btrfsprim.MaxKey),
@@ -164,7 +204,8 @@ func (path Path) NodeExpectations(ctx context.Context, failOpen bool) (_ btrfsvo
 			Level:      containers.OptionalValue(lastElem.ToLevel),
 			Generation: containers.OptionalValue(lastElem.ToGeneration),
 			Owner: func(owner btrfsprim.ObjID, gen btrfsprim.Generation) error {
-				return firstElem.Tree.TreeCheckOwner(ctx, failOpen, owner, gen)
+				return checkOwner(ctx, firstElem.Forrest, lastElem.FromTree, failOpen,
+					owner, gen)
 			},
 			MinItem: containers.OptionalValue(lastElem.ToMinKey),
 			MaxItem: containers.OptionalValue(lastElem.ToMaxKey),
diff --git a/lib/btrfs/io3_btree.go b/lib/btrfs/io3_btree.go
index 50736cf..c9e1d79 100644
--- a/lib/btrfs/io3_btree.go
+++ b/lib/btrfs/io3_btree.go
@@ -44,7 +44,7 @@ func (fs *FS) AcquireNode(ctx context.Context, addr btrfsvol.LogicalAddr, exp bt
 	if nodeEntry.node != nil {
 		if err := exp.Check(nodeEntry.node); err != nil {
 			fs.cacheNodes.Release(addr)
-			return nil, fmt.Errorf("btrfstree.ReadNode: node@%v: %w", addr, err) // fmt.Errorf("btrfs.FS.AcquireNode: node@%v: %w", addr, err)
+			return nil, fmt.Errorf("btrfs.FS.AcquireNode: node@%v: %w", addr, err)
 		}
 	}
 
diff --git a/lib/btrfsutil/old_rebuilt_forrest.go b/lib/btrfsutil/old_rebuilt_forrest.go
index 0a3106d..b03ddc2 100644
--- a/lib/btrfsutil/old_rebuilt_forrest.go
+++ b/lib/btrfsutil/old_rebuilt_forrest.go
@@ -367,7 +367,7 @@ func (tree oldRebuiltTree) TreeWalk(ctx context.Context, cbs btrfstree.TreeWalkH
 			if cbs.Node != nil && !visitedNodes.Has(indexItem.Value.Node.LAddr) {
 				nodePath := btrfstree.Path{
 					btrfstree.PathRoot{
-						Tree:         tree,
+						Forrest:      tree.forrest,
 						TreeID:       tree.ID,
 						ToAddr:       indexItem.Value.Node.LAddr,
 						ToGeneration: indexItem.Value.Node.Generation,
@@ -386,7 +386,7 @@ func (tree oldRebuiltTree) TreeWalk(ctx context.Context, cbs btrfstree.TreeWalkH
 			item := node.BodyLeaf[indexItem.Value.Slot]
 			itemPath := btrfstree.Path{
 				btrfstree.PathRoot{
-					Tree:         tree,
+					Forrest:      tree.forrest,
 					TreeID:       tree.ID,
 					ToAddr:       indexItem.Value.Node.LAddr,
 					ToGeneration: indexItem.Value.Node.Generation,
@@ -418,59 +418,28 @@ func (tree oldRebuiltTree) TreeWalk(ctx context.Context, cbs btrfstree.TreeWalkH
 	tree.forrest.ReleaseNode(node)
 }
 
-// TreeCheckOwner implements btrfstree.Tree.
-func (tree oldRebuiltTree) TreeCheckOwner(ctx context.Context, failOpen bool, owner btrfsprim.ObjID, gen btrfsprim.Generation) error {
-	var uuidTree oldRebuiltTree
-	for {
-		// Main.
-		if owner == tree.ID {
-			return nil
-		}
-		if tree.ParentUUID == (btrfsprim.UUID{}) {
-			return fmt.Errorf("owner=%v is not acceptable in this tree",
-				owner)
-		}
-		if gen > tree.ParentGen {
-			return fmt.Errorf("claimed owner=%v might be acceptable in this tree (if generation<=%v) but not with claimed generation=%v",
-				owner, tree.ParentGen, gen)
-		}
-
-		// Loop update.
-		if uuidTree.forrest == nil {
-			uuidTree = tree.forrest.RebuiltTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
-			if uuidTree.RootErr != nil {
-				return nil //nolint:nilerr // fail open
-			}
-		}
-		parentIDItem, err := uuidTree.TreeLookup(ctx, btrfsitem.UUIDToKey(tree.ParentUUID))
-		if err != nil {
-			if failOpen {
-				return nil
-			}
-			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-				owner, gen, err)
-		}
-		switch parentIDBody := parentIDItem.Body.(type) {
-		case *btrfsitem.UUIDMap:
-			tree = tree.forrest.RebuiltTree(ctx, parentIDBody.ObjID)
-			if tree.RootErr != nil {
-				if failOpen {
-					return nil
-				}
-				return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-					owner, gen, tree.RootErr)
-			}
-		case *btrfsitem.Error:
-			if failOpen {
-				return nil
-			}
-			return fmt.Errorf("unable to determine whether owner=%v generation=%v is acceptable: %w",
-				owner, gen, parentIDBody.Err)
-		default:
-			// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
-			// btrfsitem.UUIDMap or btrfsitem.Error without this code also being updated.
-			panic(fmt.Errorf("should not happen: UUID_SUBVOL item has unexpected type: %T", parentIDBody))
-		}
+// TreeParentID implements btrfstree.Tree.
+func (tree oldRebuiltTree) TreeParentID(ctx context.Context) (btrfsprim.ObjID, btrfsprim.Generation, error) {
+	if tree.ParentUUID == (btrfsprim.UUID{}) {
+		return 0, 0, nil
+	}
+	uuidTree := tree.forrest.RebuiltTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
+	if uuidTree.RootErr != nil {
+		return 0, 0, uuidTree.RootErr
+	}
+	parentIDItem, err := uuidTree.TreeLookup(ctx, btrfsitem.UUIDToKey(tree.ParentUUID))
+	if err != nil {
+		return 0, 0, err
+	}
+	switch parentIDBody := parentIDItem.Body.(type) {
+	case *btrfsitem.UUIDMap:
+		return parentIDBody.ObjID, tree.ParentGen, nil
+	case *btrfsitem.Error:
+		return 0, 0, parentIDBody.Err
+	default:
+		// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
+		// btrfsitem.UUIDMap or btrfsitem.Error without this code also being updated.
+		panic(fmt.Errorf("should not happen: UUID_SUBVOL item has unexpected type: %T", parentIDBody))
 	}
 }
 
diff --git a/lib/btrfsutil/rebuilt_forrest.go b/lib/btrfsutil/rebuilt_forrest.go
index ba88bbc..6231563 100644
--- a/lib/btrfsutil/rebuilt_forrest.go
+++ b/lib/btrfsutil/rebuilt_forrest.go
@@ -278,7 +278,7 @@ func (ts *RebuiltForrest) RebuiltListRoots(ctx context.Context) map[btrfsprim.Ob
 	defer ts.treesMu.Unlock()
 	ret := make(map[btrfsprim.ObjID]containers.Set[btrfsvol.LogicalAddr])
 	for treeID, tree := range ts.trees {
-		if tree != nil {
+		if tree != nil && len(tree.Roots) > 0 {
 			ret[treeID] = tree.Roots
 		}
 	}
diff --git a/lib/containers/arcache.go b/lib/containers/arcache.go
index 29ec030..deb80f0 100644
--- a/lib/containers/arcache.go
+++ b/lib/containers/arcache.go
@@ -504,9 +504,12 @@ func (c *arCache[K, V]) Acquire(ctx context.Context, k K) *V {
 	switch {
 	case c.liveByName[k] != nil: // cache-hit
 		entry = c.liveByName[k]
-		if entry.List != &c.frequentPinned {
-			// Move to frequentPinned (unless it's already
-			// there; in which case, don't bother).
+		// Move to frequentPinned, unless:
+		//
+		//  - it's already there; in which case, don't bother
+		//  - it's in recentPinned; don't count "nested" uses
+		//    as "frequent" uses.
+		if entry.List != &c.frequentPinned && entry.List != &c.recentPinned {
 			entry.List.Delete(entry)
 			c.frequentPinned.Store(entry)
 		}