1 files changed, 78 insertions, 0 deletions
diff --git a/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go
new file mode 100644
index 0000000..a3e724e
--- /dev/null
+++ b/cmd/btrfs-rec/inspect/rebuildmappings/process_matchsums_exact.go
@@ -0,0 +1,78 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package rebuildmappings
+
+import (
+	"context"
+
+	"github.com/datawire/dlib/dlog"
+	"golang.org/x/text/number"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfssum"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+	"git.lukeshu.com/btrfs-progs-ng/lib/containers"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+)
+
+func matchBlockGroupSums(ctx context.Context,
+	fs *btrfs.FS,
+	blockgroups map[btrfsvol.LogicalAddr]BlockGroup,
+	physicalSums map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr],
+	logicalSums SumRunWithGaps[btrfsvol.LogicalAddr],
+) error {
+	regions := ListUnmappedPhysicalRegions(fs)
+	numBlockgroups := len(blockgroups)
+	for i, bgLAddr := range maps.SortedKeys(blockgroups) {
+		blockgroup := blockgroups[bgLAddr]
+		bgRun := SumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
+		if len(bgRun.Runs) == 0 {
+			dlog.Errorf(ctx, "(%v/%v) blockgroup[laddr=%v] can't be matched because it has 0 runs",
+				i+1, numBlockgroups, bgLAddr)
+			continue
+		}
+
+		var matches []btrfsvol.QualifiedPhysicalAddr
+		if err := WalkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
+			rawMatches := indexAll[int, btrfssum.ShortSum](region, bgRun)
+			for _, match := range rawMatches {
+				matches = append(matches, btrfsvol.QualifiedPhysicalAddr{
+					Dev:  devID,
+					Addr: region.Addr + (btrfsvol.PhysicalAddr(match) * btrfssum.BlockSize),
+				})
+			}
+			return nil
+		}); err != nil {
+			return err
+		}
+
+		lvl := dlog.LogLevelError
+		if len(matches) == 1 {
+			lvl = dlog.LogLevelInfo
+		}
+		dlog.Logf(ctx, lvl, "(%v/%v) blockgroup[laddr=%v] has %v matches based on %v coverage from %v runs",
+			i+1, numBlockgroups, bgLAddr, len(matches), number.Percent(bgRun.PctFull()), len(bgRun.Runs))
+		if len(matches) != 1 {
+			continue
+		}
+
+		mapping := btrfsvol.Mapping{
+			LAddr:      blockgroup.LAddr,
+			PAddr:      matches[0],
+			Size:       blockgroup.Size,
+			SizeLocked: true,
+			Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
+				OK:  true,
+				Val: blockgroup.Flags,
+			},
+		}
+		if err := fs.LV.AddMapping(mapping); err != nil {
+			dlog.Errorf(ctx, "error: %v", err)
+			continue
+		}
+		delete(blockgroups, bgLAddr)
+	}
+	return nil
+}