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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package rebuildnodes
import (
"context"
"fmt"
"strings"
"github.com/datawire/dlib/dlog"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
"git.lukeshu.com/btrfs-progs-ng/lib/containers"
"git.lukeshu.com/btrfs-progs-ng/lib/maps"
)
type uuidMap struct {
ObjID2UUID map[btrfsprim.ObjID]btrfsprim.UUID
UUID2ObjID map[btrfsprim.UUID]btrfsprim.ObjID
TreeParent map[btrfsprim.ObjID]btrfsprim.UUID
SeenTrees containers.Set[btrfsprim.ObjID]
}
func (m uuidMap) missingRootItems() containers.Set[btrfsprim.ObjID] {
missing := make(containers.Set[btrfsprim.ObjID])
for treeID := range m.SeenTrees {
if _, ok := m.ObjID2UUID[treeID]; !ok && treeID != btrfsprim.ROOT_TREE_OBJECTID {
missing.Insert(treeID)
continue
}
if _, ok := m.TreeParent[treeID]; !ok && treeID >= btrfsprim.FIRST_FREE_OBJECTID && treeID <= btrfsprim.LAST_FREE_OBJECTID {
missing.Insert(treeID)
}
}
return missing
}
// ParentTree implements btrfstree.NodeFile.
func (m uuidMap) ParentTree(tree btrfsprim.ObjID) (btrfsprim.ObjID, bool) {
if tree < btrfsprim.FIRST_FREE_OBJECTID || tree > btrfsprim.LAST_FREE_OBJECTID {
// no parent
return 0, true
}
parentUUID, ok := m.TreeParent[tree]
if !ok {
// could not look up parent info
return 0, false
}
if parentUUID == (btrfsprim.UUID{}) {
// no parent
return 0, true
}
parentObjID, ok := m.UUID2ObjID[parentUUID]
if !ok {
// could not look up parent info
return 0, false
}
return parentObjID, true
}
type fullAncestorLister struct {
uuidMap uuidMap
treeAncestors map[btrfsprim.ObjID]containers.Set[btrfsprim.ObjID]
memos map[btrfsprim.ObjID]containers.Set[btrfsprim.ObjID]
}
func newFullAncestorLister(uuidMap uuidMap, treeAncestors map[btrfsprim.ObjID]containers.Set[btrfsprim.ObjID]) fullAncestorLister {
return fullAncestorLister{
uuidMap: uuidMap,
treeAncestors: treeAncestors,
memos: make(map[btrfsprim.ObjID]containers.Set[btrfsprim.ObjID]),
}
}
type loopError []btrfsprim.ObjID
func (le loopError) Error() string {
var buf strings.Builder
buf.WriteString("loop: ")
for i, treeID := range le {
if i > 0 {
buf.WriteString("->")
}
fmt.Fprintf(&buf, "%d", treeID)
}
return buf.String()
}
func (fa fullAncestorLister) GetFullAncestors(child btrfsprim.ObjID) containers.Set[btrfsprim.ObjID] {
if memoized, ok := fa.memos[child]; ok {
if memoized == nil {
panic(loopError{child})
}
return memoized
}
fa.memos[child] = nil
defer func() {
if r := recover(); r != nil {
if le, ok := r.(loopError); ok {
r = append(loopError{child}, le...)
}
panic(r)
}
}()
ret := make(containers.Set[btrfsprim.ObjID])
defer func() {
fa.memos[child] = ret
}()
// Try to use '.uuidMap' instead of '.treeAncestors' if possible.
knownAncestors := make(containers.Set[btrfsprim.ObjID])
if parent, ok := fa.uuidMap.ParentTree(child); ok {
if parent == 0 {
return ret
}
knownAncestors.Insert(parent)
} else {
knownAncestors.InsertFrom(fa.treeAncestors[child])
}
for _, ancestor := range maps.SortedKeys(knownAncestors) {
ret.Insert(ancestor)
ret.InsertFrom(fa.GetFullAncestors(ancestor))
}
return ret
}
func (m uuidMap) considerAncestors(ctx context.Context, treeAncestors map[btrfsprim.ObjID]containers.Set[btrfsprim.ObjID]) {
if missing := m.missingRootItems(); len(missing) == 0 {
return
} else {
dlog.Infof(ctx, "Rebuilding %d root items...", len(missing))
}
fa := newFullAncestorLister(m, treeAncestors)
for _, missingRoot := range maps.SortedKeys(m.missingRootItems()) {
if _, ok := m.TreeParent[missingRoot]; ok {
// This one is incomplete because it doesn't have a UUID, not
// because it doesn't have a parent.
continue
}
potentialParents := make(containers.Set[btrfsprim.ObjID])
potentialParents.InsertFrom(fa.GetFullAncestors(missingRoot))
for _, ancestor := range maps.SortedKeys(fa.GetFullAncestors(missingRoot)) {
potentialParents.DeleteFrom(fa.GetFullAncestors(ancestor))
}
if len(potentialParents) == 1 {
parent := potentialParents.TakeOne()
dlog.Infof(ctx, "... the parent of %v is %v", missingRoot, parent)
parentUUID, ok := m.ObjID2UUID[parent]
if !ok {
dlog.Errorf(ctx, "... but can't synthesize a root item because UUID of %v is unknown", parent)
continue
}
m.TreeParent[missingRoot] = parentUUID
}
}
if missing := m.missingRootItems(); len(missing) > 0 {
dlog.Errorf(ctx, "... could not rebuild root items for %d trees: %v", len(missing), maps.SortedKeys(missing))
} else {
dlog.Info(ctx, "... rebuilt all root items")
}
}
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