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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"
"sync"
"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/diskio"
"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.Forrest, and adds similar
// broken-tree handling to OldRebuiltForrest. However, it 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.Path`
//
// - it does not keep track of errors encountered in a tree
//
// Additionally, it provides some functionality that OldRebuiltForrest
// does not:
//
// - it provides a RebuiltForrest.RebuiltListRoots() method for
// listing how trees have been repaired.
//
// - it provides a RebuiltTree.RebuiltAddRoot() method for repairing a
// tree.
//
// - it provides several RebuiltTree methods that provide advice on
// what roots should be added to a tree in order to repair it:
//
// .RebuiltItems() and RebuiltPotentialItems() to compare what's
// in the tree and what could be in the tree.
//
// .RebuiltLeafToRoots() to map potential items to things that can
// be passed to .RebuiltAddRoot().
//
// .RebuiltCOWDistance() and .RebuiltShouldReplace() to provide
// information on deciding on an option from
// .RebuiltLeafToRoots().
//
// A zero RebuiltForrest is invalid; it must be initialized with
// NewRebuiltForrest().
type RebuiltForrest struct {
// static
file diskio.File[btrfsvol.LogicalAddr]
sb btrfstree.Superblock
graph Graph
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]
nodesMu sync.Mutex
nodes containers.ARCache[btrfsvol.LogicalAddr, *btrfstree.Node]
}
// NewRebuiltForrest returns a new RebuiltForrest instance. All of
// the callbacks must be non-nil.
func NewRebuiltForrest(file diskio.File[btrfsvol.LogicalAddr], sb btrfstree.Superblock, graph Graph, cb RebuiltForrestCallbacks) *RebuiltForrest {
return &RebuiltForrest{
file: file,
sb: sb,
graph: graph,
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),
},
nodes: containers.ARCache[btrfsvol.LogicalAddr, *btrfstree.Node]{
MaxLen: textui.Tunable(8),
OnRemove: func(_ btrfsvol.LogicalAddr, node *btrfstree.Node) {
node.Free()
},
},
}
}
// RebuiltTree 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.
//
// This is identical to .ForrestLookup(), but returns a concrete type
// rather than an interface.
func (ts *RebuiltForrest) RebuiltTree(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.RebuiltAddRoot() 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.RebuiltAddRoot(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)
}
}
}
// RebuiltListRoots 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) RebuiltListRoots(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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