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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsutil
import (
"context"
"github.com/datawire/dlib/dlog"
"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/slices"
"git.lukeshu.com/btrfs-progs-ng/lib/textui"
)
type RebuiltForrestCallbacks interface {
AddedItem(ctx context.Context, tree btrfsprim.ObjID, key btrfsprim.Key)
AddedRoot(ctx context.Context, tree btrfsprim.ObjID, root btrfsvol.LogicalAddr)
LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool)
LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool)
}
// RebuiltForrest is an abstraction for rebuilding and accessing
// potentially broken btrees.
//
// It is conceptually a btrfstree.TreeOperator, and adds similar
// broken-tree handling to OldRebuiltForrest. However, the API is
// different than btrfstree.TreeOperator, and is much more efficient
// than OldRebuiltForrest.
//
// The efficiency improvements are possible because of the API
// differences, which are necessary for how it is used in
// rebuildtrees:
//
// - it consumes an already-read Graph instead of reading the graph
// itself
//
// - it does not use `btrfstree.TreePath`
//
// - it does not keep track of errors encountered in a tree
//
// Additionally, it provides some functionality that OldRebuiltForrest
// does not:
//
// - it provides a .LeafToRoots() method to advise on what
// additional roots should be added
//
// - it provides a .COWDistance() method to compare how related two
// trees are
//
// A zero RebuiltForrest is invalid; it must be initialized with
// NewRebuiltForrest().
type RebuiltForrest struct {
// static
sb btrfstree.Superblock
graph Graph
keyIO *KeyIO
cb RebuiltForrestCallbacks
// mutable
treesMu nestedMutex
trees map[btrfsprim.ObjID]*RebuiltTree // must hold .treesMu to access
leafs containers.ARCache[btrfsprim.ObjID, map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr]]
incItems containers.ARCache[btrfsprim.ObjID, *itemIndex]
excItems containers.ARCache[btrfsprim.ObjID, *itemIndex]
}
// NewRebuiltForrest returns a new RebuiltForrest instance. All of
// the callbacks must be non-nil.
func NewRebuiltForrest(sb btrfstree.Superblock, graph Graph, keyIO *KeyIO, cb RebuiltForrestCallbacks) *RebuiltForrest {
return &RebuiltForrest{
sb: sb,
graph: graph,
keyIO: keyIO,
cb: cb,
trees: make(map[btrfsprim.ObjID]*RebuiltTree),
leafs: containers.ARCache[btrfsprim.ObjID, map[btrfsvol.LogicalAddr]containers.Set[btrfsvol.LogicalAddr]]{
MaxLen: textui.Tunable(8),
},
incItems: containers.ARCache[btrfsprim.ObjID, *itemIndex]{
MaxLen: textui.Tunable(8),
},
excItems: containers.ARCache[btrfsprim.ObjID, *itemIndex]{
MaxLen: textui.Tunable(8),
},
}
}
// Tree returns a given tree, initializing it if nescessary. If it is
// unable to initialize the tree, then nil is returned, and nothing is
// done to the forrest.
//
// The tree is initialized with the normal root node of the tree.
func (ts *RebuiltForrest) Tree(ctx context.Context, treeID btrfsprim.ObjID) *RebuiltTree {
ctx = ts.treesMu.Lock(ctx)
defer ts.treesMu.Unlock()
if !ts.addTree(ctx, treeID, nil) {
return nil
}
return ts.trees[treeID]
}
func (ts *RebuiltForrest) addTree(ctx context.Context, treeID btrfsprim.ObjID, stack []btrfsprim.ObjID) (ok bool) {
if tree, ok := ts.trees[treeID]; ok {
return tree != nil
}
defer func() {
if !ok {
// Store a negative cache of this. tree.AddRoot() for the ROOT or UUID
// trees will call .flushNegativeCache().
ts.trees[treeID] = nil
}
}()
stack = append(stack, treeID)
ctx = dlog.WithField(ctx, "btrfs.util.rebuilt-forrest.add-tree", stack)
dlog.Info(ctx, "adding tree...")
if slices.Contains(treeID, stack[:len(stack)-1]) {
dlog.Errorf(ctx, "failed to add tree: loop detected: %v", stack)
return false
}
tree := &RebuiltTree{
ID: treeID,
Roots: make(containers.Set[btrfsvol.LogicalAddr]),
forrest: ts,
}
var root btrfsvol.LogicalAddr
switch treeID {
case btrfsprim.ROOT_TREE_OBJECTID:
root = ts.sb.RootTree
case btrfsprim.CHUNK_TREE_OBJECTID:
root = ts.sb.ChunkTree
case btrfsprim.TREE_LOG_OBJECTID:
root = ts.sb.LogTree
case btrfsprim.BLOCK_GROUP_TREE_OBJECTID:
root = ts.sb.BlockGroupRoot
default:
if !ts.addTree(ctx, btrfsprim.ROOT_TREE_OBJECTID, stack) {
dlog.Error(ctx, "failed to add tree: add ROOT_TREE")
return false
}
rootOff, rootItem, ok := ts.cb.LookupRoot(ctx, treeID)
if !ok {
dlog.Error(ctx, "failed to add tree: lookup ROOT_ITEM")
return false
}
root = rootItem.ByteNr
tree.UUID = rootItem.UUID
if rootItem.ParentUUID != (btrfsprim.UUID{}) {
tree.ParentGen = rootOff
if !ts.addTree(ctx, btrfsprim.UUID_TREE_OBJECTID, stack) {
return false
}
parentID, ok := ts.cb.LookupUUID(ctx, rootItem.ParentUUID)
if !ok {
dlog.Error(ctx, "failed to add tree: lookup UUID")
return false
}
if !ts.addTree(ctx, parentID, stack) {
dlog.Error(ctx, "failed to add tree: add parent tree")
return false
}
tree.Parent = ts.trees[parentID]
}
}
ts.trees[treeID] = tree
if root != 0 {
tree.AddRoot(ctx, root)
}
return true
}
func (ts *RebuiltForrest) flushNegativeCache(ctx context.Context) {
_ = ts.treesMu.Lock(ctx)
defer ts.treesMu.Unlock()
for treeID, tree := range ts.trees {
if tree == nil {
delete(ts.trees, treeID)
}
}
}
// ListRoots returns a listing of all initialized trees and their root
// nodes.
//
// Do not mutate the set of roots for a tree; it is a pointer to the
// RebuiltForrest's internal set!
func (ts *RebuiltForrest) ListRoots(ctx context.Context) map[btrfsprim.ObjID]containers.Set[btrfsvol.LogicalAddr] {
_ = ts.treesMu.Lock(ctx)
defer ts.treesMu.Unlock()
ret := make(map[btrfsprim.ObjID]containers.Set[btrfsvol.LogicalAddr])
for treeID, tree := range ts.trees {
if tree != nil {
ret[treeID] = tree.Roots
}
}
return ret
}
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