1 files changed, 78 insertions, 0 deletions
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildmappings/blockgroups.go b/lib/btrfsprogs/btrfsinspect/rebuildmappings/blockgroups.go
new file mode 100644
index 0000000..15df6da
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildmappings/blockgroups.go
@@ -0,0 +1,78 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package rebuildmappings
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+
+	"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/maps"
+)
+
+type NodeScanResults = map[btrfsvol.DeviceID]btrfsinspect.ScanOneDeviceResult
+
+type BlockGroup struct {
+	LAddr btrfsvol.LogicalAddr
+	Size  btrfsvol.AddrDelta
+	Flags btrfsvol.BlockGroupFlags
+}
+
+func ReadNodeScanResults(fs *btrfs.FS, filename string) (map[btrfsvol.LogicalAddr]BlockGroup, 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
+}
+
+func ReduceScanResults(fs *btrfs.FS, scanResults NodeScanResults) (map[btrfsvol.LogicalAddr]BlockGroup, error) {
+	// Reduce
+	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{}{}
+		}
+	}
+
+	// Sanity check
+	bgList := maps.Keys(bgSet)
+	sort.Slice(bgList, func(i, j int) bool {
+		return bgList[i].LAddr < bgList[j].LAddr
+	})
+	var pos btrfsvol.LogicalAddr
+	for _, bg := range bgList {
+		if bg.LAddr < pos || bg.Size < 0 {
+			return nil, fmt.Errorf("found block groups are inconsistent")
+		}
+		pos = bg.LAddr.Add(bg.Size)
+	}
+
+	// Return
+	bgMap := make(map[btrfsvol.LogicalAddr]BlockGroup, len(bgSet))
+	for bg := range bgSet {
+		bgMap[bg.LAddr] = bg
+	}
+	return bgMap, nil
+}