Factor rebuildmappings.MapLogicalSums out of inspect_dbgsums

2 files changed, 95 insertions, 70 deletions

diff --git a/cmd/btrfs-rec/inspect_dbgsums.go b/cmd/btrfs-rec/inspect_dbgsums.go
index b46a305..b5abf8f 100644
--- a/cmd/btrfs-rec/inspect_dbgsums.go
+++ b/cmd/btrfs-rec/inspect_dbgsums.go
@@ -8,7 +8,6 @@ import (
 	"bufio"
 	"fmt"
 	"os"
-	"strings"
 
 	"git.lukeshu.com/go/lowmemjson"
 	"github.com/datawire/dlib/dlog"
@@ -16,9 +15,7 @@ import (
 	"github.com/spf13/cobra"
 
 	"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/maps"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsinspect/rebuildmappings"
 )
 
 func init() {
@@ -42,74 +39,10 @@ func init() {
 			}
 			dlog.Infof(ctx, "... done reading %q", args[0])
 
-			dlog.Info(ctx, "Mapping the logical address space...")
-			type record struct {
-				Gen btrfs.Generation
-				Sum btrfssum.ShortSum
-			}
-			addrspace := make(map[btrfsvol.LogicalAddr]record)
-			var sumSize int
-			for _, devResults := range scanResults {
-				sumSize = devResults.Checksums.ChecksumSize
-				for _, sumItem := range devResults.FoundExtentCSums {
-					_ = sumItem.Sums.Walk(ctx, func(pos btrfsvol.LogicalAddr, sum btrfssum.ShortSum) error {
-						new := record{
-							Gen: sumItem.Generation,
-							Sum: sum,
-						}
-						if old, ok := addrspace[pos]; ok {
-							switch {
-							case old.Gen > new.Gen:
-								// do nothing
-							case old.Gen < new.Gen:
-								addrspace[pos] = new
-							case old.Gen == new.Gen:
-								if old != new {
-									dlog.Errorf(ctx, "mismatch of laddr=%v sum: %v != %v", pos, old, new)
-								}
-							}
-						} else {
-							addrspace[pos] = new
-						}
-						return nil
-					})
-				}
-			}
-			if len(addrspace) == 0 {
+			flattened := rebuildmappings.MapLogicalSums(ctx, scanResults)
+			if len(flattened.Runs) == 0 {
 				return fmt.Errorf("no checksums were found in the scan")
 			}
-			dlog.Info(ctx, "... done mapping")
-
-			dlog.Info(ctx, "Flattening the map ...")
-			var flattened btrfssum.SumRunWithGaps[btrfsvol.LogicalAddr]
-			var curAddr btrfsvol.LogicalAddr
-			var curSums strings.Builder
-			for _, laddr := range maps.SortedKeys(addrspace) {
-				if laddr != curAddr+(btrfsvol.LogicalAddr(curSums.Len()/sumSize)*btrfssum.BlockSize) {
-					if curSums.Len() > 0 {
-						flattened.Runs = append(flattened.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
-							ChecksumSize: sumSize,
-							Addr:         curAddr,
-							Sums:         btrfssum.ShortSum(curSums.String()),
-						})
-					}
-					curAddr = laddr
-					curSums.Reset()
-				}
-				curSums.WriteString(string(addrspace[laddr].Sum))
-			}
-			if curSums.Len() > 0 {
-				flattened.Runs = append(flattened.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
-					ChecksumSize: sumSize,
-					Addr:         curAddr,
-					Sums:         btrfssum.ShortSum(curSums.String()),
-				})
-			}
-			flattened.Addr = flattened.Runs[0].Addr
-			last := flattened.Runs[len(flattened.Runs)-1]
-			end := last.Addr.Add(last.Size())
-			flattened.Size = end.Sub(flattened.Addr)
-			dlog.Info(ctx, "... done flattening")
 
 			dlog.Info(ctx, "Writing addrspace sums to stdout...")
 			buffer := bufio.NewWriter(os.Stdout)
diff --git a/lib/btrfsprogs/btrfsinspect/rebuildmappings/csumitems.go b/lib/btrfsprogs/btrfsinspect/rebuildmappings/csumitems.go
new file mode 100644
index 0000000..90a15b0
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/rebuildmappings/csumitems.go
@@ -0,0 +1,92 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package rebuildmappings
+
+import (
+	"context"
+	"strings"
+
+	"github.com/datawire/dlib/dlog"
+
+	"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/btrfsprogs/btrfsinspect"
+	"git.lukeshu.com/btrfs-progs-ng/lib/maps"
+)
+
+func MapLogicalSums(ctx context.Context, scanResults btrfsinspect.ScanDevicesResult) btrfssum.SumRunWithGaps[btrfsvol.LogicalAddr] {
+	dlog.Info(ctx, "Mapping the logical address space...")
+	type record struct {
+		Gen btrfs.Generation
+		Sum btrfssum.ShortSum
+	}
+	addrspace := make(map[btrfsvol.LogicalAddr]record)
+	var sumSize int
+	for _, devResults := range scanResults {
+		sumSize = devResults.Checksums.ChecksumSize
+		for _, sumItem := range devResults.FoundExtentCSums {
+			_ = sumItem.Sums.Walk(ctx, func(pos btrfsvol.LogicalAddr, sum btrfssum.ShortSum) error {
+				new := record{
+					Gen: sumItem.Generation,
+					Sum: sum,
+				}
+				if old, ok := addrspace[pos]; ok {
+					switch {
+					case old.Gen > new.Gen:
+						// do nothing
+					case old.Gen < new.Gen:
+						addrspace[pos] = new
+					case old.Gen == new.Gen:
+						if old != new {
+							dlog.Errorf(ctx, "mismatch of laddr=%v sum: %v != %v", pos, old, new)
+						}
+					}
+				} else {
+					addrspace[pos] = new
+				}
+				return nil
+			})
+		}
+	}
+	dlog.Info(ctx, "... done mapping")
+
+	var flattened btrfssum.SumRunWithGaps[btrfsvol.LogicalAddr]
+	if len(addrspace) == 0 {
+		return flattened
+	}
+
+	dlog.Info(ctx, "Flattening the map ...")
+	var curAddr btrfsvol.LogicalAddr
+	var curSums strings.Builder
+	for _, laddr := range maps.SortedKeys(addrspace) {
+		if laddr != curAddr+(btrfsvol.LogicalAddr(curSums.Len()/sumSize)*btrfssum.BlockSize) {
+			if curSums.Len() > 0 {
+				flattened.Runs = append(flattened.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
+					ChecksumSize: sumSize,
+					Addr:         curAddr,
+					Sums:         btrfssum.ShortSum(curSums.String()),
+				})
+			}
+			curAddr = laddr
+			curSums.Reset()
+		}
+		curSums.WriteString(string(addrspace[laddr].Sum))
+	}
+	if curSums.Len() > 0 {
+		flattened.Runs = append(flattened.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
+			ChecksumSize: sumSize,
+			Addr:         curAddr,
+			Sums:         btrfssum.ShortSum(curSums.String()),
+		})
+	}
+	flattened.Addr = flattened.Runs[0].Addr
+	last := flattened.Runs[len(flattened.Runs)-1]
+	end := last.Addr.Add(last.Size())
+	flattened.Size = end.Sub(flattened.Addr)
+	dlog.Info(ctx, "... done flattening")
+
+	return flattened
+}