1 files changed, 267 insertions, 0 deletions
diff --git a/lib/btrfsprogs/btrfsinspect/scanforextents/csums.go b/lib/btrfsprogs/btrfsinspect/scanforextents/csums.go
new file mode 100644
index 0000000..6a42946
--- /dev/null
+++ b/lib/btrfsprogs/btrfsinspect/scanforextents/csums.go
@@ -0,0 +1,267 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package scanforextents
+
+import (
+	"context"
+	"encoding/gob"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"strings"
+	"sync"
+
+	"github.com/datawire/dlib/dgroup"
+	"github.com/datawire/dlib/dlog"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"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/btrfsutil"
+)
+
+const csumBlockSize = 4 * 1024
+
+type ShortSum string
+
+type LogicalSumRun struct {
+	Addr btrfsvol.LogicalAddr
+	Sums string
+}
+
+type AllSums struct {
+	ChecksumSize int
+	Logical      []LogicalSumRun
+	Physical     map[btrfsvol.DeviceID]string
+}
+
+func ReadAllSums(filename string) (AllSums, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return AllSums{}, err
+	}
+	defer fh.Close()
+	var val AllSums
+	if err := gob.NewDecoder(fh).Decode(&val); err != nil {
+		return AllSums{}, err
+	}
+	return val, nil
+}
+
+func WriteAllSums(w io.Writer, sums AllSums) error {
+	return gob.NewEncoder(w).Encode(sums)
+}
+
+func (as AllSums) SumForPAddr(paddr btrfsvol.QualifiedPhysicalAddr) (ShortSum, bool) {
+	run, ok := as.Physical[paddr.Dev]
+	if !ok {
+		return "", false
+	}
+	off := int(paddr.Addr/csumBlockSize) * as.ChecksumSize
+	if off+as.ChecksumSize > len(run) {
+		return "", false
+	}
+	return ShortSum(run[off : off+as.ChecksumSize]), true
+}
+
+func (as AllSums) SumForLAddr(laddr btrfsvol.LogicalAddr) (ShortSum, bool) {
+	for _, run := range as.Logical {
+		size := btrfsvol.AddrDelta(len(run.Sums)/as.ChecksumSize) * csumBlockSize
+		if run.Addr > laddr {
+			return "", false
+		}
+		if run.Addr.Add(size) <= laddr {
+			continue
+		}
+		off := int(laddr.Sub(run.Addr)/csumBlockSize) * as.ChecksumSize
+		return ShortSum(run.Sums[off : off+as.ChecksumSize]), true
+	}
+	return "", false
+}
+
+func (as AllSums) WalkLogical(fn func(btrfsvol.LogicalAddr, ShortSum) error) error {
+	for _, run := range as.Logical {
+		for laddr, off := run.Addr, 0; off < len(run.Sums); laddr, off = laddr+csumBlockSize, off+as.ChecksumSize {
+			if err := fn(laddr, ShortSum(run.Sums[off:off+as.ChecksumSize])); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func SumEverything(ctx context.Context, fs *btrfs.FS) (AllSums, error) {
+	var ret AllSums
+
+	// ChecksumSize
+	var alg btrfssum.CSumType
+	if err := func() error {
+		sb, err := fs.Superblock()
+		if err != nil {
+			return err
+		}
+		alg = sb.ChecksumType
+		ret.ChecksumSize = alg.Size()
+		return nil
+	}(); err != nil {
+		return ret, err
+	}
+
+	// Logical
+	dlog.Info(ctx, "Walking CSUM_TREE...")
+	func() {
+		var curAddr btrfsvol.LogicalAddr
+		var curSums strings.Builder
+		btrfsutil.NewBrokenTrees(ctx, fs).TreeWalk(ctx, btrfs.CSUM_TREE_OBJECTID,
+			func(err *btrfs.TreeError) {
+				dlog.Error(ctx, err)
+			},
+			btrfs.TreeWalkHandler{
+				Item: func(path btrfs.TreePath, item btrfs.Item) error {
+					if item.Key.ItemType != btrfsitem.EXTENT_CSUM_KEY {
+						return nil
+					}
+					body := item.Body.(btrfsitem.ExtentCSum)
+
+					for i, sum := range body.Sums {
+						laddr := btrfsvol.LogicalAddr(item.Key.Offset) + (btrfsvol.LogicalAddr(i) * csumBlockSize)
+						if laddr != curAddr {
+							if curSums.Len() > 0 {
+								ret.Logical = append(ret.Logical, LogicalSumRun{
+									Addr: curAddr,
+									Sums: curSums.String(),
+								})
+							}
+							curAddr = laddr
+							curSums.Reset()
+						}
+						curSums.Write(sum[:ret.ChecksumSize])
+					}
+					return nil
+				},
+			},
+		)
+		if curSums.Len() > 0 {
+			ret.Logical = append(ret.Logical, LogicalSumRun{
+				Addr: curAddr,
+				Sums: curSums.String(),
+			})
+		}
+	}()
+	if err := ctx.Err(); err != nil {
+		return ret, err
+	}
+	dlog.Info(ctx, "... done walking")
+	runtime.GC()
+	dlog.Info(ctx, "... GC'd")
+
+	// Physical
+	dlog.Info(ctx, "Summing devices...")
+	if err := func() error {
+		devs := fs.LV.PhysicalVolumes()
+
+		var mu sync.Mutex
+		ret.Physical = make(map[btrfsvol.DeviceID]string, len(devs))
+
+		grp := dgroup.NewGroup(ctx, dgroup.GroupConfig{})
+		for devID, dev := range devs {
+			devID, dev := devID, dev
+			grp.Go(dev.Name(), func(ctx context.Context) error {
+				devSize := dev.Size()
+				numSums := int(devSize / csumBlockSize)
+				sums := make([]byte, numSums*ret.ChecksumSize)
+				lastPct := -1
+				progress := func(curSum int) {
+					pct := int(100 * float64(curSum) / float64(numSums))
+					if pct != lastPct || curSum == numSums {
+						dlog.Infof(ctx, "... dev[%q] summed %v%%",
+							dev.Name(), pct)
+						lastPct = pct
+					}
+				}
+				for i := 0; i < numSums; i++ {
+					if err := ctx.Err(); err != nil {
+						return err
+					}
+					progress(i)
+					sum, err := ChecksumPhysical(dev, alg, btrfsvol.PhysicalAddr(i*csumBlockSize))
+					if err != nil {
+						return err
+					}
+					copy(sums[i*ret.ChecksumSize:], sum[:ret.ChecksumSize])
+				}
+				progress(numSums)
+				sumsStr := string(sums)
+				mu.Lock()
+				ret.Physical[devID] = sumsStr
+				mu.Unlock()
+				return nil
+			})
+		}
+		return grp.Wait()
+	}(); err != nil {
+		return ret, err
+	}
+	dlog.Info(ctx, "... done summing devices")
+	runtime.GC()
+	dlog.Info(ctx, "... GC'd")
+
+	// Return
+	return ret, nil
+}
+
+func ChecksumLogical(fs btrfs.Trees, alg btrfssum.CSumType, laddr btrfsvol.LogicalAddr) (btrfssum.CSum, error) {
+	var dat [csumBlockSize]byte
+	if _, err := fs.ReadAt(dat[:], laddr); err != nil {
+		return btrfssum.CSum{}, err
+	}
+	return alg.Sum(dat[:])
+}
+
+func ChecksumPhysical(dev *btrfs.Device, alg btrfssum.CSumType, paddr btrfsvol.PhysicalAddr) (btrfssum.CSum, error) {
+	var dat [csumBlockSize]byte
+	if _, err := dev.ReadAt(dat[:], paddr); err != nil {
+		return btrfssum.CSum{}, err
+	}
+	return alg.Sum(dat[:])
+}
+
+func ChecksumQualifiedPhysical(fs *btrfs.FS, alg btrfssum.CSumType, paddr btrfsvol.QualifiedPhysicalAddr) (btrfssum.CSum, error) {
+	dev := fs.LV.PhysicalVolumes()[paddr.Dev]
+	if dev == nil {
+		return btrfssum.CSum{}, fmt.Errorf("no such device_id=%v", paddr.Dev)
+	}
+	return ChecksumPhysical(dev, alg, paddr.Addr)
+}
+
+func LookupCSum(fs btrfs.Trees, alg btrfssum.CSumType, laddr btrfsvol.LogicalAddr) (map[btrfsvol.LogicalAddr]btrfssum.CSum, error) {
+	item, err := fs.TreeSearch(btrfs.CSUM_TREE_OBJECTID, func(key btrfs.Key, size uint32) int {
+		itemBeg := btrfsvol.LogicalAddr(key.ObjectID)
+		numSums := int64(size) / int64(alg.Size())
+		itemEnd := itemBeg + btrfsvol.LogicalAddr(numSums*csumBlockSize)
+		switch {
+		case itemEnd <= laddr:
+			return 1
+		case laddr < itemBeg:
+			return -1
+		default:
+			return 0
+		}
+	})
+	if err != nil {
+		return nil, err
+	}
+	body, ok := item.Body.(btrfsitem.ExtentCSum)
+	if !ok {
+		return nil, fmt.Errorf("item body is %T not ExtentCSum", item.Body)
+	}
+	ret := make(map[btrfsvol.LogicalAddr]btrfssum.CSum, len(body.Sums))
+	for i, sum := range body.Sums {
+		ret[btrfsvol.LogicalAddr(item.Key.ObjectID)+(btrfsvol.LogicalAddr(i)*csumBlockSize)] = sum
+	}
+	return ret, nil
+}