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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package rebuildmappings
import (
"context"
"sort"
"strings"
"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/containers"
"git.lukeshu.com/btrfs-progs-ng/lib/slices"
)
func extractLogicalSums(ctx context.Context, scanResults ScanDevicesResult) sumRunWithGaps[btrfsvol.LogicalAddr] {
var records []FoundExtentCSum
for _, devResults := range scanResults {
records = append(records, devResults.FoundExtentCSums...)
}
// Sort lower-generation items earlier; then sort by addr.
sort.Slice(records, func(i, j int) bool {
a, b := records[i], records[j]
switch {
case a.Generation < b.Generation:
return true
case a.Generation > b.Generation:
return false
default:
return a.Sums.Addr < b.Sums.Addr
}
})
if len(records) == 0 {
return sumRunWithGaps[btrfsvol.LogicalAddr]{}
}
sumSize := records[0].Sums.ChecksumSize
// Now build them in to a coherent address space.
//
// We can't just reverse-sort by generation to avoid mutations, because given
//
// gen1 AAAAAAA
// gen2 BBBBBBBB
// gen3 CCCCCCC
//
// "AAAAAAA" shouldn't be present, and if we just discard "BBBBBBBB"
// because it conflicts with "CCCCCCC", then we would erroneously
// include "AAAAAAA".
addrspace := new(containers.RBTree[FoundExtentCSum])
for _, newRecord := range records {
for {
conflict := addrspace.Search(func(oldRecord FoundExtentCSum) int {
switch {
case newRecord.Sums.Addr.Add(newRecord.Sums.Size()) <= oldRecord.Sums.Addr:
// 'newRecord' is wholly to the left of 'oldRecord'.
return -1
case oldRecord.Sums.Addr.Add(oldRecord.Sums.Size()) <= newRecord.Sums.Addr:
// 'oldRecord' is wholly to the left of 'newRecord'.
return 1
default:
// There is some overlap.
return 0
}
})
if conflict == nil {
// We can insert it
addrspace.Insert(newRecord)
break
}
oldRecord := conflict.Value
if oldRecord == newRecord {
// Duplicates are to be expected.
break
}
if oldRecord.Generation < newRecord.Generation {
// Newer generation wins.
addrspace.Delete(conflict)
// loop around to check for more conflicts
continue
}
if oldRecord.Generation > newRecord.Generation {
// We sorted them! This shouldn't happen.
panic("should not happen")
}
// Since sums are stored multiple times (RAID?), but may
// be split between items differently between copies, we
// should take the union (after verifying that they
// agree on the overlapping part).
overlapBeg := slices.Max(
oldRecord.Sums.Addr,
newRecord.Sums.Addr)
overlapEnd := slices.Min(
oldRecord.Sums.Addr.Add(oldRecord.Sums.Size()),
newRecord.Sums.Addr.Add(newRecord.Sums.Size()))
oldOverlapBeg := int(overlapBeg.Sub(oldRecord.Sums.Addr)/btrfssum.BlockSize) * sumSize
oldOverlapEnd := int(overlapEnd.Sub(oldRecord.Sums.Addr)/btrfssum.BlockSize) * sumSize
oldOverlap := oldRecord.Sums.Sums[oldOverlapBeg:oldOverlapEnd]
newOverlapBeg := int(overlapBeg.Sub(newRecord.Sums.Addr)/btrfssum.BlockSize) * sumSize
newOverlapEnd := int(overlapEnd.Sub(newRecord.Sums.Addr)/btrfssum.BlockSize) * sumSize
newOverlap := newRecord.Sums.Sums[newOverlapBeg:newOverlapEnd]
if oldOverlap != newOverlap {
dlog.Errorf(ctx, "mismatch: {gen:%v, addr:%v, size:%v} conflicts with {gen:%v, addr:%v, size:%v}",
oldRecord.Generation, oldRecord.Sums.Addr, oldRecord.Sums.Size(),
newRecord.Generation, newRecord.Sums.Addr, newRecord.Sums.Size())
break
}
// OK, we match, so take the union.
var prefix, suffix btrfssum.ShortSum
switch {
case oldRecord.Sums.Addr < overlapBeg:
prefix = oldRecord.Sums.Sums[:oldOverlapBeg]
case newRecord.Sums.Addr < overlapBeg:
prefix = newRecord.Sums.Sums[:newOverlapBeg]
}
switch {
case oldRecord.Sums.Addr.Add(oldRecord.Sums.Size()) > overlapEnd:
suffix = oldRecord.Sums.Sums[oldOverlapEnd:]
case newRecord.Sums.Addr.Add(newRecord.Sums.Size()) > overlapEnd:
suffix = newRecord.Sums.Sums[newOverlapEnd:]
}
unionRecord := FoundExtentCSum{
Generation: oldRecord.Generation,
Sums: btrfsitem.ExtentCSum{
SumRun: btrfssum.SumRun[btrfsvol.LogicalAddr]{
ChecksumSize: oldRecord.Sums.ChecksumSize,
Addr: slices.Min(oldRecord.Sums.Addr, newRecord.Sums.Addr),
Sums: prefix + oldOverlap + suffix,
},
},
}
addrspace.Delete(conflict)
newRecord = unionRecord
// loop around to check for more conflicts
}
}
// Now flatten that RBTree in to a sumRunWithGaps.
var flattened sumRunWithGaps[btrfsvol.LogicalAddr]
var curAddr btrfsvol.LogicalAddr
var curSums strings.Builder
addrspace.Range(func(node *containers.RBNode[FoundExtentCSum]) bool {
curEnd := curAddr + (btrfsvol.LogicalAddr(curSums.Len()/sumSize) * btrfssum.BlockSize)
if node.Value.Sums.Addr != curEnd {
if curSums.Len() > 0 {
flattened.Runs = append(flattened.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
ChecksumSize: sumSize,
Addr: curAddr,
Sums: btrfssum.ShortSum(curSums.String()),
})
}
curAddr = node.Value.Sums.Addr
curSums.Reset()
}
curSums.WriteString(string(node.Value.Sums.Sums))
return true
})
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)
return flattened
}
func listUnmappedLogicalRegions(fs *btrfs.FS, logicalSums sumRunWithGaps[btrfsvol.LogicalAddr]) []btrfssum.SumRun[btrfsvol.LogicalAddr] {
// There are a lot of ways this algorithm could be made
// faster.
var ret []btrfssum.SumRun[btrfsvol.LogicalAddr]
var cur struct {
Addr btrfsvol.LogicalAddr
Size btrfsvol.AddrDelta
}
for _, run := range logicalSums.Runs {
for addr := run.Addr; addr < run.Addr.Add(run.Size()); addr += btrfssum.BlockSize {
if _, maxlen := fs.LV.Resolve(addr); maxlen < btrfssum.BlockSize {
if cur.Size == 0 {
cur.Addr = addr
cur.Size = 0
}
cur.Size += btrfssum.BlockSize
} else if cur.Size > 0 {
begIdx := int(cur.Addr.Sub(run.Addr)/btrfssum.BlockSize) * run.ChecksumSize
lenIdx := (int(cur.Size) / btrfssum.BlockSize) * run.ChecksumSize
endIdx := begIdx + lenIdx
ret = append(ret, btrfssum.SumRun[btrfsvol.LogicalAddr]{
ChecksumSize: run.ChecksumSize,
Addr: cur.Addr,
Sums: run.Sums[begIdx:endIdx],
})
cur.Size = 0
}
}
if cur.Size > 0 {
begIdx := int(cur.Addr.Sub(run.Addr)/btrfssum.BlockSize) * run.ChecksumSize
lenIdx := (int(cur.Size) / btrfssum.BlockSize) * run.ChecksumSize
endIdx := begIdx + lenIdx
ret = append(ret, btrfssum.SumRun[btrfsvol.LogicalAddr]{
ChecksumSize: run.ChecksumSize,
Addr: cur.Addr,
Sums: run.Sums[begIdx:endIdx],
})
cur.Size = 0
}
}
return ret
}
func sumsForLogicalRegion(sums sumRunWithGaps[btrfsvol.LogicalAddr], beg btrfsvol.LogicalAddr, size btrfsvol.AddrDelta) sumRunWithGaps[btrfsvol.LogicalAddr] {
runs := sumRunWithGaps[btrfsvol.LogicalAddr]{
Addr: beg,
Size: size,
}
for laddr := beg; laddr < beg.Add(size); {
run, next, ok := sums.RunForAddr(laddr)
if !ok {
laddr = next
continue
}
off := int((laddr-run.Addr)/btrfssum.BlockSize) * run.ChecksumSize
deltaAddr := slices.Min[btrfsvol.AddrDelta](
size-laddr.Sub(beg),
btrfsvol.AddrDelta((len(run.Sums)-off)/run.ChecksumSize)*btrfssum.BlockSize)
deltaOff := int(deltaAddr/btrfssum.BlockSize) * run.ChecksumSize
runs.Runs = append(runs.Runs, btrfssum.SumRun[btrfsvol.LogicalAddr]{
ChecksumSize: run.ChecksumSize,
Addr: laddr,
Sums: run.Sums[off : off+deltaOff],
})
laddr = laddr.Add(deltaAddr)
}
return runs
}
|
