rebuildnodes: Refactor the node-graph stuff in to a separate sub-package

2 files changed, 322 insertions, 0 deletions

diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/graph.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/graph.go
new file mode 100644
index 0000000..7ae3b89
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/graph.go
@@ -0,0 +1,157 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package graph
+
+import (
+	"fmt"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
+)
+
+type Node struct {
+	Level      uint8
+	Generation btrfsprim.Generation
+	Owner      btrfsprim.ObjID
+	NumItems   uint32
+	MinItem    btrfsprim.Key
+	MaxItem    btrfsprim.Key
+}
+
+type Edge struct {
+	FromTree btrfsprim.ObjID
+	FromNode btrfsvol.LogicalAddr
+	FromItem int
+
+	ToNode       btrfsvol.LogicalAddr
+	ToLevel      uint8
+	ToKey        btrfsprim.Key
+	ToGeneration btrfsprim.Generation
+}
+
+func (kp Edge) String() string {
+	return fmt.Sprintf(`{t:%v,n:%v}[%d]->{n:%v,l:%v,g:%v,k:(%d,%v,%d)}`,
+		kp.FromTree, kp.FromNode, kp.FromItem,
+		kp.ToNode, kp.ToLevel, kp.ToGeneration,
+		kp.ToKey.ObjectID,
+		kp.ToKey.ItemType,
+		kp.ToKey.Offset)
+}
+
+type Graph struct {
+	Nodes     map[btrfsvol.LogicalAddr]Node
+	BadNodes  map[btrfsvol.LogicalAddr]error
+	EdgesFrom map[btrfsvol.LogicalAddr][]*Edge
+	EdgesTo   map[btrfsvol.LogicalAddr][]*Edge
+}
+
+func (g Graph) insertEdge(kp Edge) {
+	ptr := &kp
+	if kp.ToNode == 0 {
+		panic("kp.ToNode should not be zero")
+	}
+	g.EdgesFrom[kp.FromNode] = append(g.EdgesFrom[kp.FromNode], ptr)
+	g.EdgesTo[kp.ToNode] = append(g.EdgesTo[kp.ToNode], ptr)
+}
+
+func (g Graph) insertTreeRoot(sb btrfstree.Superblock, treeID btrfsprim.ObjID) {
+	treeInfo, err := btrfstree.LookupTreeRoot(nil, sb, treeID)
+	if err != nil {
+		// This shouldn't ever happen for treeIDs that are
+		// mentioned directly in the superblock; which are the
+		// only trees for which we should call
+		// .insertTreeRoot().
+		panic(fmt.Errorf("LookupTreeRoot(%v): %w", treeID, err))
+	}
+	if treeInfo.RootNode == 0 {
+		return
+	}
+	g.insertEdge(Edge{
+		FromTree:     treeID,
+		ToNode:       treeInfo.RootNode,
+		ToLevel:      treeInfo.Level,
+		ToGeneration: treeInfo.Generation,
+	})
+}
+
+func New(sb btrfstree.Superblock) *Graph {
+	g := &Graph{
+		Nodes:     make(map[btrfsvol.LogicalAddr]Node),
+		BadNodes:  make(map[btrfsvol.LogicalAddr]error),
+		EdgesFrom: make(map[btrfsvol.LogicalAddr][]*Edge),
+		EdgesTo:   make(map[btrfsvol.LogicalAddr][]*Edge),
+	}
+
+	// These 4 trees are mentioned directly in the superblock, so
+	// they are always seen.
+	g.insertTreeRoot(sb, btrfsprim.ROOT_TREE_OBJECTID)
+	g.insertTreeRoot(sb, btrfsprim.CHUNK_TREE_OBJECTID)
+	g.insertTreeRoot(sb, btrfsprim.TREE_LOG_OBJECTID)
+	g.insertTreeRoot(sb, btrfsprim.BLOCK_GROUP_TREE_OBJECTID)
+
+	return g
+}
+
+func (g *Graph) InsertNode(nodeRef *diskio.Ref[btrfsvol.LogicalAddr, btrfstree.Node]) {
+	for _, item := range nodeRef.Data.BodyLeaf {
+		switch itemBody := item.Body.(type) {
+		case btrfsitem.Root:
+			g.insertEdge(Edge{
+				FromTree:     item.Key.ObjectID,
+				ToNode:       itemBody.ByteNr,
+				ToLevel:      itemBody.Level,
+				ToGeneration: itemBody.Generation,
+			})
+		}
+	}
+
+	g.Nodes[nodeRef.Addr] = Node{
+		Level:      nodeRef.Data.Head.Level,
+		Generation: nodeRef.Data.Head.Generation,
+		Owner:      nodeRef.Data.Head.Owner,
+		NumItems:   nodeRef.Data.Head.NumItems,
+		MinItem:    discardOK(nodeRef.Data.MinItem()),
+		MaxItem:    discardOK(nodeRef.Data.MaxItem()),
+	}
+	for i, kp := range nodeRef.Data.BodyInternal {
+		g.insertEdge(Edge{
+			FromTree:     nodeRef.Data.Head.Owner,
+			FromNode:     nodeRef.Addr,
+			FromItem:     i,
+			ToNode:       kp.BlockPtr,
+			ToLevel:      nodeRef.Data.Head.Level - 1,
+			ToKey:        kp.Key,
+			ToGeneration: kp.Generation,
+		})
+	}
+}
+
+func (g *Graph) FinalCheck(fs diskio.File[btrfsvol.LogicalAddr], sb btrfstree.Superblock, progress func(n, d int)) error {
+	total := len(g.EdgesTo)
+	done := 0
+	progress(done, total)
+	for laddr := range g.EdgesTo {
+		if _, ok := g.Nodes[laddr]; !ok {
+			_, err := btrfstree.ReadNode[btrfsvol.LogicalAddr](fs, sb, laddr, btrfstree.NodeExpectations{
+				LAddr: containers.Optional[btrfsvol.LogicalAddr]{OK: true, Val: laddr},
+			})
+			if err == nil {
+				return fmt.Errorf("node@%v exists but was not in node scan results", laddr)
+			}
+			g.BadNodes[laddr] = err
+		}
+		done++
+		progress(done, total)
+	}
+	return nil
+}
+
+func discardOK[T any](val T, _ bool) T {
+	return val
+}
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go
new file mode 100644
index 0000000..e76985c
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildnodes/graph/loops.go
@@ -0,0 +1,165 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package graph
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/datawire/dlib/derror"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+	"git.lukeshu.com/btrfs-progs-ng/lib/slices"
+)
+
+func (g Graph) ShowLoops(out io.Writer) {
+	orphans := make(containers.Set[btrfsvol.LogicalAddr])
+	for node := range g.Nodes {
+		if len(g.EdgesTo[node]) == 0 {
+			orphans.Insert(node)
+		}
+	}
+
+	loopWalk(out, g, 0)
+	for _, orphan := range maps.SortedKeys(orphans) {
+		loopWalk(out, g, orphan)
+	}
+}
+
+func loopWalk(out io.Writer, scanData Graph, stack ...btrfsvol.LogicalAddr) {
+	for _, kp := range scanData.EdgesFrom[stack[len(stack)-1]] {
+		childStack := append(stack, kp.ToNode)
+		if slices.Contains(kp.ToNode, stack) {
+			loopRender(out, scanData, childStack...)
+		} else {
+			loopWalk(out, scanData, childStack...)
+		}
+	}
+}
+
+func nodeRender(scanData Graph, node btrfsvol.LogicalAddr) []string {
+	if node == 0 {
+		return []string{"root"}
+	} else if nodeData, ok := scanData.Nodes[node]; ok {
+		return []string{
+			fmt.Sprintf("{addr:      %v,", node),
+			fmt.Sprintf(" level:     %v,", nodeData.Level),
+			fmt.Sprintf(" gen:       %v,", nodeData.Generation),
+			fmt.Sprintf(" num_items: %v,", nodeData.NumItems),
+			fmt.Sprintf(" min_item:  {%d,%v,%d},",
+				nodeData.MinItem.ObjectID,
+				nodeData.MinItem.ItemType,
+				nodeData.MinItem.Offset),
+			fmt.Sprintf(" max_item:  {%d,%v,%d}}",
+				nodeData.MaxItem.ObjectID,
+				nodeData.MaxItem.ItemType,
+				nodeData.MaxItem.Offset),
+		}
+	} else if nodeErr, ok := scanData.BadNodes[node]; ok {
+		return []string{
+			fmt.Sprintf("{addr:%v,", node),
+			fmt.Sprintf(" err:%q}", nodeErr.Error()),
+		}
+	} else {
+		panic("should not happen")
+	}
+}
+
+func edgeRender(scanData Graph, kp Edge) []string {
+	a := fmt.Sprintf("[%d]={", kp.FromItem)
+	b := strings.Repeat(" ", len(a))
+	ret := []string{
+		a + fmt.Sprintf("ToNode:  %v,", kp.ToNode),
+		b + fmt.Sprintf("ToLevel: %v,", kp.ToLevel),
+		b + fmt.Sprintf("ToGen:   %v,", kp.ToGeneration),
+		b + fmt.Sprintf("ToKey:   {%d,%v,%d}}",
+			kp.ToKey.ObjectID,
+			kp.ToKey.ItemType,
+			kp.ToKey.Offset),
+	}
+
+	var err error
+	if toNode, ok := scanData.Nodes[kp.ToNode]; !ok {
+		err = scanData.BadNodes[kp.ToNode]
+	} else {
+		err = checkNodeExpectations(kp, toNode)
+	}
+	if err != nil {
+		c := strings.Repeat(" ", len(a)-1)
+		ret = append(ret,
+			c+"^",
+			c+"`-err="+strings.ReplaceAll(err.Error(), "\n", "\n"+c+"      "),
+		)
+	}
+	return ret
+}
+
+func loopRender(out io.Writer, scanData Graph, stack ...btrfsvol.LogicalAddr) {
+	var lines []string
+	add := func(suffixes []string) {
+		curLen := 0
+		for _, line := range lines {
+			if len(line) > curLen {
+				curLen = len(line)
+			}
+		}
+		for i, suffix := range suffixes {
+			if len(lines) <= i {
+				lines = append(lines, "")
+			}
+			if len(lines[i]) < curLen {
+				if i == 0 {
+					lines[i] += strings.Repeat("-", curLen-len(lines[i])-1) + ">"
+				} else {
+					lines[i] += strings.Repeat(" ", curLen-len(lines[i]))
+				}
+			}
+			lines[i] += suffix
+		}
+	}
+
+	for i, node := range stack {
+		if i > 0 {
+			for _, kp := range scanData.EdgesTo[node] {
+				if kp.FromNode == stack[i-1] {
+					add(edgeRender(scanData, *kp))
+					break
+				}
+			}
+		}
+		add(nodeRender(scanData, node))
+	}
+
+	fmt.Fprintln(out, "loop:")
+	for _, line := range lines {
+		fmt.Fprintln(out, "    "+line)
+	}
+}
+
+func checkNodeExpectations(kp Edge, toNode Node) error {
+	var errs derror.MultiError
+	if toNode.Level != kp.ToLevel {
+		errs = append(errs, fmt.Errorf("kp.level=%v != node.level=%v",
+			kp.ToLevel, toNode.Level))
+	}
+	if toNode.Generation != kp.ToGeneration {
+		errs = append(errs, fmt.Errorf("kp.generation=%v != node.generation=%v",
+			kp.ToGeneration, toNode.Generation))
+	}
+	if toNode.NumItems == 0 {
+		errs = append(errs, fmt.Errorf("node.num_items=0"))
+	} else if kp.ToKey != (btrfsprim.Key{}) && toNode.MinItem != kp.ToKey {
+		errs = append(errs, fmt.Errorf("kp.key=%v != node.items[0].key=%v",
+			kp.ToKey, toNode.MinItem))
+	}
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}