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// Copyright (C) 2022 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package main
import (
"context"
"os"
"runtime"
"sort"
"sync"
"github.com/datawire/dlib/dgroup"
"github.com/datawire/dlib/dlog"
"github.com/datawire/ocibuild/pkg/cliutil"
"github.com/spf13/cobra"
"golang.org/x/exp/constraints"
"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/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfsprogs/btrfsutil"
)
const csumBlockSize = 4 * 1024
type shortSum string
func init() {
inspectors = append(inspectors, subcommand{
Command: cobra.Command{
Use: "scan-for-extents",
Args: cliutil.WrapPositionalArgs(cobra.NoArgs),
},
RunE: func(fs *btrfs.FS, cmd *cobra.Command, _ []string) error {
ctx := cmd.Context()
dlog.Info(ctx, "Reading checksum tree...")
sum2laddrs := listUnmappedCheckummedExtents(ctx, fs)
dlog.Info(ctx, "... done reading checksum tree")
dlog.Info(ctx, "Pruning duplicate sums...")
for sum, addrs := range sum2laddrs {
if len(addrs) != 1 {
delete(sum2laddrs, sum)
}
}
dlog.Info(ctx, "... done pruning")
devs := fs.LV.PhysicalVolumes()
gaps := listPhysicalGaps(fs)
var mu sync.Mutex
sum2paddrs := make(map[shortSum][]btrfsvol.QualifiedPhysicalAddr)
grp := dgroup.NewGroup(ctx, dgroup.GroupConfig{})
for devID := range gaps {
devGaps := gaps[devID]
dev := devs[devID]
grp.Go(dev.Name(), func(ctx context.Context) error {
devSum2paddrs, err := scanOneDev(ctx, dev, devGaps, sum2laddrs)
mu.Lock()
for sum, paddrs := range devSum2paddrs {
sum2paddrs[sum] = append(sum2paddrs[sum], paddrs...)
}
mu.Unlock()
return err
})
}
if err := grp.Wait(); err != nil {
return err
}
dlog.Info(ctx, "Rebuilding mappings from results...")
rebuildMappings(ctx, fs, devs, sum2laddrs, sum2paddrs)
dlog.Info(ctx, "... done rebuilding mappings")
dlog.Infof(ctx, "Writing reconstructed mappings to stdout...")
if err := writeMappingsJSON(os.Stdout, fs); err != nil {
return err
}
return nil
},
})
}
func listUnmappedCheckummedExtents(ctx context.Context, fs *btrfs.FS) map[shortSum][]btrfsvol.LogicalAddr {
sum2laddrs := make(map[shortSum][]btrfsvol.LogicalAddr)
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 paddrs, _ := fs.LV.Resolve(laddr); len(paddrs) > 0 {
continue
}
sum := shortSum(_sum[:body.ChecksumSize])
sum2laddrs[sum] = append(sum2laddrs[sum], laddr)
}
return nil
},
},
)
return sum2laddrs
}
type physicalGap struct {
Beg, End btrfsvol.PhysicalAddr
}
func listPhysicalGaps(fs *btrfs.FS) map[btrfsvol.DeviceID][]physicalGap {
gaps := make(map[btrfsvol.DeviceID][]physicalGap)
pos := make(map[btrfsvol.DeviceID]btrfsvol.PhysicalAddr)
mappings := fs.LV.Mappings()
sort.Slice(mappings, func(i, j int) bool {
return mappings[i].PAddr.Cmp(mappings[j].PAddr) < 0
})
for _, mapping := range mappings {
if pos[mapping.PAddr.Dev] < mapping.PAddr.Addr {
gaps[mapping.PAddr.Dev] = append(gaps[mapping.PAddr.Dev], physicalGap{
Beg: pos[mapping.PAddr.Dev],
End: mapping.PAddr.Addr,
})
}
if pos[mapping.PAddr.Dev] < mapping.PAddr.Addr.Add(mapping.Size) {
pos[mapping.PAddr.Dev] = mapping.PAddr.Addr.Add(mapping.Size)
}
}
for devID, dev := range fs.LV.PhysicalVolumes() {
devSize := dev.Size()
if pos[devID] < devSize {
gaps[devID] = append(gaps[devID], physicalGap{
Beg: pos[devID],
End: devSize,
})
}
}
return gaps
}
func roundUp[T constraints.Integer](x, multiple T) T {
return ((x + multiple - 1) / multiple) * multiple
}
func scanOneDev[T any](ctx context.Context, dev *btrfs.Device, gaps []physicalGap, sumsToScanFor map[shortSum]T) (map[shortSum][]btrfsvol.QualifiedPhysicalAddr, error) {
dlog.Infof(ctx, "... dev[%q] Scanning for extents...", dev.Name())
sb, err := dev.Superblock()
if err != nil {
return nil, err
}
var totalBlocks int64
for _, gap := range gaps {
for paddr := roundUp(gap.Beg, csumBlockSize); paddr+csumBlockSize <= gap.End; paddr += csumBlockSize {
totalBlocks++
}
}
lastProgress := -1
var curBlock int64
progress := func() {
pct := int(100 * float64(curBlock) / float64(totalBlocks))
if pct != lastProgress || curBlock == totalBlocks {
dlog.Infof(ctx, "... dev[%q] scanned %v%%",
dev.Name(), pct)
lastProgress = pct
if pct%5 == 0 {
runtime.GC()
}
}
}
sumSize := sb.ChecksumType.Size()
var buf [csumBlockSize]byte
devSum2paddrs := make(map[shortSum][]btrfsvol.QualifiedPhysicalAddr)
for _, gap := range gaps {
for paddr := roundUp(gap.Beg, csumBlockSize); paddr+csumBlockSize <= gap.End; paddr += csumBlockSize {
progress()
curBlock++
if err := ctx.Err(); err != nil {
return nil, err
}
_, err := dev.ReadAt(buf[:], paddr)
if err != nil {
dlog.Error(ctx, err)
continue
}
_sum, err := sb.ChecksumType.Sum(buf[:])
if err != nil {
dlog.Error(ctx, err)
continue
}
sum := shortSum(_sum[:sumSize])
if _, interesting := sumsToScanFor[sum]; !interesting {
continue
}
devSum2paddrs[sum] = append(devSum2paddrs[sum], btrfsvol.QualifiedPhysicalAddr{
Dev: sb.DevItem.DevID,
Addr: paddr,
})
}
}
progress()
return devSum2paddrs, nil
}
func rebuildMappings(ctx context.Context, fs *btrfs.FS,
devs map[btrfsvol.DeviceID]*btrfs.Device,
sum2laddrs map[shortSum][]btrfsvol.LogicalAddr,
sum2paddrs map[shortSum][]btrfsvol.QualifiedPhysicalAddr) {
totalPairs := len(sum2paddrs)
lastProgress := -1
var donePairs int
progress := func() {
pct := int(100 * float64(donePairs) / float64(totalPairs))
if pct != lastProgress || donePairs == totalPairs {
dlog.Infof(ctx, "... rebuilt %v%% (%v/%v)", pct, donePairs, totalPairs)
lastProgress = pct
if pct%5 == 0 {
runtime.GC()
}
}
}
for sum, paddrs := range sum2paddrs {
progress()
if len(paddrs) == 1 {
mapping := btrfsvol.Mapping{
LAddr: sum2laddrs[sum][0],
PAddr: paddrs[0],
Size: csumBlockSize,
}
if err := fs.LV.AddMapping(mapping); err != nil {
dlog.Errorf(ctx, "... dev[%q] error: adding chunk: %v",
devs[paddrs[0].Dev].Name(), err)
}
} else {
delete(sum2paddrs, sum)
delete(sum2laddrs, sum)
}
donePairs++
}
progress()
}
|
