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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"
"github.com/datawire/dlib/dlog"
"golang.org/x/text/number"
"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/containers"
"git.lukeshu.com/btrfs-progs-ng/lib/maps"
"git.lukeshu.com/btrfs-progs-ng/lib/textui"
)
var minFuzzyPct = textui.Tunable(0.5)
type fuzzyRecord struct {
PAddr btrfsvol.QualifiedPhysicalAddr
N int
}
func (a fuzzyRecord) Compare(b fuzzyRecord) int {
switch {
case a.N < b.N:
return -1
case a.N > b.N:
return 1
default:
return 0
}
}
func fuzzyMatchBlockGroupSums(ctx context.Context,
fs *btrfs.FS,
blockgroups map[btrfsvol.LogicalAddr]BlockGroup,
physicalSums map[btrfsvol.DeviceID]btrfssum.SumRun[btrfsvol.PhysicalAddr],
logicalSums SumRunWithGaps[btrfsvol.LogicalAddr],
) error {
_ctx := ctx
ctx = dlog.WithField(_ctx, "btrfsinspect.rebuild-mappings.substep", "indexing")
dlog.Info(ctx, "Indexing physical regions...") // O(m)
regions := ListUnmappedPhysicalRegions(fs)
physicalIndex := make(map[btrfssum.ShortSum][]btrfsvol.QualifiedPhysicalAddr)
if err := WalkUnmappedPhysicalRegions(ctx, physicalSums, regions, func(devID btrfsvol.DeviceID, region btrfssum.SumRun[btrfsvol.PhysicalAddr]) error {
return region.Walk(ctx, func(paddr btrfsvol.PhysicalAddr, sum btrfssum.ShortSum) error {
physicalIndex[sum] = append(physicalIndex[sum], btrfsvol.QualifiedPhysicalAddr{
Dev: devID,
Addr: paddr,
})
return nil
})
}); err != nil {
return err
}
dlog.Info(ctx, "... done indexing")
ctx = dlog.WithField(_ctx, "btrfsinspect.rebuild-mappings.substep", "searching")
dlog.Info(ctx, "Searching...")
numBlockgroups := len(blockgroups)
for i, bgLAddr := range maps.SortedKeys(blockgroups) {
blockgroup := blockgroups[bgLAddr]
bgRun := SumsForLogicalRegion(logicalSums, blockgroup.LAddr, blockgroup.Size)
d := bgRun.PatLen()
matches := make(map[btrfsvol.QualifiedPhysicalAddr]int)
if err := bgRun.Walk(ctx, func(laddr btrfsvol.LogicalAddr, sum btrfssum.ShortSum) error { // O(n*…
off := laddr.Sub(bgRun.Addr)
for _, paddr := range physicalIndex[sum] { // …log(m)) expected but …m) worst
key := btrfsvol.QualifiedPhysicalAddr{
Dev: paddr.Dev,
Addr: paddr.Addr.Add(-off),
}
matches[key]++
}
return nil
}); err != nil {
return err
}
best := lowestN[fuzzyRecord]{N: 2}
for paddr, n := range matches { // O(m)
best.Insert(fuzzyRecord{
PAddr: paddr,
N: d - n,
})
}
var apply bool
var matchesStr string
switch len(best.Dat) {
case 0: // can happen if there are no sums in the run
matchesStr = ""
case 1: // not sure how this can happen, but whatev
pct := float64(d-best.Dat[0].N) / float64(d)
matchesStr = textui.Sprintf("%v", number.Percent(pct))
apply = pct > minFuzzyPct
case 2:
pct := float64(d-best.Dat[0].N) / float64(d)
pct2 := float64(d-best.Dat[1].N) / float64(d)
matchesStr = textui.Sprintf("best=%v secondbest=%v", number.Percent(pct), number.Percent(pct2))
apply = pct > minFuzzyPct && pct2 < minFuzzyPct
}
lvl := dlog.LogLevelError
if apply {
lvl = dlog.LogLevelInfo
}
dlog.Logf(ctx, lvl, "(%v/%v) blockgroup[laddr=%v] matches=[%s]; bestpossible=%v (based on %v runs)",
i+1, numBlockgroups, bgLAddr, matchesStr, number.Percent(bgRun.PctFull()), len(bgRun.Runs))
if !apply {
continue
}
mapping := btrfsvol.Mapping{
LAddr: blockgroup.LAddr,
PAddr: best.Dat[0].PAddr,
Size: blockgroup.Size,
SizeLocked: true,
Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
OK: true,
Val: blockgroup.Flags,
},
}
if err := fs.LV.AddMapping(mapping); err != nil {
dlog.Errorf(ctx, "error: %v", err)
continue
}
delete(blockgroups, bgLAddr)
}
dlog.Info(ctx, "done searching")
return nil
}
type lowestN[T containers.Ordered[T]] struct {
N int
Dat []T
}
func (l *lowestN[T]) Insert(v T) {
switch {
case len(l.Dat) < l.N:
l.Dat = append(l.Dat, v)
case v.Compare(l.Dat[0]) < 0:
l.Dat[0] = v
default:
return
}
sort.Slice(l.Dat, func(i, j int) bool {
return l.Dat[i].Compare(l.Dat[j]) < 0
})
}
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