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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package scanforextents
import (
"context"
"errors"
"fmt"
"github.com/datawire/dlib/dlog"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs"
"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 ScanForExtents(ctx context.Context, fs *btrfs.FS, blockgroups *BlockGroupTree, sums AllSums) error {
sb, err := fs.Superblock()
if err != nil {
return err
}
dlog.Info(ctx, "Reverse-indexing and validating logical sums...")
sum2laddrs := make(map[ShortSum][]btrfsvol.LogicalAddr)
if err := sums.WalkLogical(func(laddr btrfsvol.LogicalAddr, expShortSum ShortSum) error {
if err := ctx.Err(); err != nil {
return err
}
readSum, err := ChecksumLogical(fs, sb.ChecksumType, laddr)
if err != nil {
if errors.Is(err, btrfsvol.ErrCouldNotMap) {
sum2laddrs[expShortSum] = append(sum2laddrs[expShortSum], laddr)
return nil
}
return err
}
readShortSum := ShortSum(readSum[:sums.ChecksumSize])
if readShortSum != expShortSum {
return fmt.Errorf("checksum mismatch at laddr=%v: CSUM_TREE=%x != read=%x",
laddr, []byte(expShortSum), []byte(readShortSum))
}
return nil
}); err != nil {
return err
}
dlog.Info(ctx, "... done reverse-indexing and validating")
dlog.Info(ctx, "Cross-referencing sums (and blockgroups) to re-construct mappings...")
newMappings := &ExtentMappings{
InLV: &fs.LV,
InBlockGroups: blockgroups,
InSums: sums,
InReverseSums: sum2laddrs,
}
devs := fs.LV.PhysicalVolumes()
gaps := ListPhysicalGaps(fs)
for _, devID := range maps.SortedKeys(gaps) {
if err := newMappings.ScanOneDev(ctx,
devID, devs[devID].Name(),
gaps[devID],
); err != nil {
return err
}
}
dlog.Info(ctx, "... done cross-referencing")
dlog.Info(ctx, "Applying those mappings...")
for laddr, mappings := range newMappings.OutSum2mappings {
if len(mappings) > 1 {
dlog.Errorf(ctx, "multiple possibilities for laddr=%v :", laddr)
for _, mapping := range mappings {
dlog.Errorf(ctx, " - %#v", *mapping)
}
continue
}
if err := fs.LV.AddMapping(*mappings[0]); err != nil {
dlog.Error(ctx, err)
}
}
dlog.Info(ctx, "... done applying")
return nil
}
type ExtentMappings struct {
// input
InLV *btrfsvol.LogicalVolume[*btrfs.Device]
InBlockGroups *BlockGroupTree
InSums AllSums
InReverseSums map[ShortSum][]btrfsvol.LogicalAddr
// state
internedMappings map[btrfsvol.Mapping]*btrfsvol.Mapping
// output
OutSum2mappings map[ShortSum][]*btrfsvol.Mapping
}
func (em *ExtentMappings) considerMapping(ctx context.Context, laddr btrfsvol.LogicalAddr, paddr btrfsvol.QualifiedPhysicalAddr) (btrfsvol.Mapping, bool) {
blockgroup := LookupBlockGroup(em.InBlockGroups, laddr, csumBlockSize)
if blockgroup == nil {
return btrfsvol.Mapping{
LAddr: laddr,
PAddr: paddr,
Size: csumBlockSize,
}, true
}
mapping := btrfsvol.Mapping{
LAddr: blockgroup.LAddr,
PAddr: btrfsvol.QualifiedPhysicalAddr{
Dev: paddr.Dev,
Addr: paddr.Addr.Add(laddr.Sub(blockgroup.LAddr)),
},
Size: blockgroup.Size,
SizeLocked: true,
Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
OK: true,
Val: blockgroup.Flags,
},
}
if !em.InLV.CouldAddMapping(mapping) {
return btrfsvol.Mapping{}, false
}
for offset := btrfsvol.AddrDelta(0); offset <= mapping.Size; offset += csumBlockSize {
expCSum, ok := em.InSums.SumForLAddr(mapping.LAddr.Add(offset))
if !ok {
continue
}
actCSum, _ := em.InSums.SumForPAddr(mapping.PAddr.Add(offset))
if actCSum != expCSum {
return btrfsvol.Mapping{}, false
}
}
return mapping, true
}
func (em *ExtentMappings) addMapping(sum ShortSum, mapping btrfsvol.Mapping) {
interned := em.internedMappings[mapping]
if interned == nil {
interned = &mapping
em.internedMappings[mapping] = interned
}
em.OutSum2mappings[sum] = append(em.OutSum2mappings[sum], interned)
}
func (em *ExtentMappings) ScanOneDev(
ctx context.Context,
devID btrfsvol.DeviceID, devName string,
gaps []PhysicalGap,
) error {
if em.internedMappings == nil {
em.internedMappings = make(map[btrfsvol.Mapping]*btrfsvol.Mapping)
}
if em.OutSum2mappings == nil {
em.OutSum2mappings = make(map[ShortSum][]*btrfsvol.Mapping)
}
dlog.Infof(ctx, "... dev[%q] Scanning for extents...", devName)
lastProgress := -1
potentialMappings := 0
return WalkGaps(ctx, gaps, csumBlockSize,
func(curBlock, totalBlocks int64) {
pct := int(100 * float64(curBlock) / float64(totalBlocks))
if pct != lastProgress || curBlock == totalBlocks {
dlog.Infof(ctx, "... dev[%q] scanned %v%% (constructed %v potential mappings)",
devName, pct, potentialMappings)
lastProgress = pct
}
},
func(paddr btrfsvol.PhysicalAddr) error {
qpaddr := btrfsvol.QualifiedPhysicalAddr{
Dev: devID,
Addr: paddr,
}
sum, _ := em.InSums.SumForPAddr(qpaddr)
for _, laddr := range em.InReverseSums[sum] {
mapping, ok := em.considerMapping(ctx, laddr, qpaddr)
if !ok {
continue
}
em.addMapping(sum, mapping)
potentialMappings++
}
return nil
},
)
}
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