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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package scanforextents
import (
"encoding/json"
"fmt"
"os"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect"
"git.lukeshu.com/btrfs-progs-ng/lib/containers"
)
type NodeScanResults = map[btrfsvol.DeviceID]btrfsinspect.ScanOneDevResult
func ReadNodeScanResults(fs *btrfs.FS, filename string) (*BlockGroupTree, error) {
scanResultsBytes, err := os.ReadFile(filename)
if err != nil {
return nil, err
}
var scanResults NodeScanResults
if err := json.Unmarshal(scanResultsBytes, &scanResults); err != nil {
return nil, err
}
bgTree, err := ReduceScanResults(fs, scanResults)
if err != nil {
return nil, err
}
return bgTree, nil
}
type BlockGroup struct {
LAddr btrfsvol.LogicalAddr
Size btrfsvol.AddrDelta
Flags btrfsvol.BlockGroupFlags
}
type BlockGroupTree = containers.RBTree[containers.NativeOrdered[btrfsvol.LogicalAddr], BlockGroup]
func LookupBlockGroup(tree *BlockGroupTree, laddr btrfsvol.LogicalAddr, size btrfsvol.AddrDelta) *BlockGroup {
a := struct {
LAddr btrfsvol.LogicalAddr
Size btrfsvol.AddrDelta
}{
LAddr: laddr,
Size: size,
}
node := tree.Search(func(b BlockGroup) int {
switch {
case a.LAddr.Add(a.Size) <= b.LAddr:
// 'a' is wholly to the left of 'b'.
return -1
case b.LAddr.Add(b.Size) <= a.LAddr:
// 'a' is wholly to the right of 'b'.
return 1
default:
// There is some overlap.
return 0
}
})
if node == nil {
return nil
}
bg := node.Value
return &bg
}
func ReduceScanResults(fs *btrfs.FS, scanResults NodeScanResults) (*BlockGroupTree, error) {
bgSet := make(map[BlockGroup]struct{})
for _, found := range scanResults {
for _, bg := range found.FoundBlockGroups {
bgSet[BlockGroup{
LAddr: btrfsvol.LogicalAddr(bg.Key.ObjectID),
Size: btrfsvol.AddrDelta(bg.Key.Offset),
Flags: bg.BG.Flags,
}] = struct{}{}
}
}
bgTree := &BlockGroupTree{
KeyFn: func(bg BlockGroup) containers.NativeOrdered[btrfsvol.LogicalAddr] {
return containers.NativeOrdered[btrfsvol.LogicalAddr]{Val: bg.LAddr}
},
}
for bg := range bgSet {
if laddr, _ := fs.LV.ResolveAny(bg.LAddr, bg.Size); laddr >= 0 {
continue
}
if LookupBlockGroup(bgTree, bg.LAddr, bg.Size) != nil {
return nil, fmt.Errorf("found block groups are inconsistent")
}
bgTree.Insert(bg)
}
return bgTree, nil
}
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