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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
// Package rebuildmappings is the guts of the `btrfs-rec inspect
// rebuild-mappings` command, which rebuilds broken
// chunk/dev-extent/blockgroup trees.
package rebuildmappings
import (
"context"
"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"
"git.lukeshu.com/btrfs-progs-ng/lib/textui"
)
func getNodeSize(fs *btrfs.FS) (btrfsvol.AddrDelta, error) {
sb, err := fs.Superblock()
if err != nil {
return 0, err
}
return btrfsvol.AddrDelta(sb.NodeSize), nil
}
func RebuildMappings(ctx context.Context, fs *btrfs.FS, scanResults ScanDevicesResult) error {
nodeSize, err := getNodeSize(fs)
if err != nil {
return err
}
var numChunks, numDevExts, numBlockGroups, numNodes int
devIDs := maps.SortedKeys(scanResults)
devices := fs.LV.PhysicalVolumes()
for _, devID := range devIDs {
if _, ok := devices[devID]; !ok {
return fmt.Errorf("device ID %v mentioned in scan results is not part of the filesystem", devID)
}
devResults := scanResults[devID]
numChunks += len(devResults.FoundChunks)
numDevExts += len(devResults.FoundDevExtents)
numBlockGroups += len(devResults.FoundBlockGroups)
for _, paddrs := range devResults.FoundNodes {
numNodes += len(paddrs)
}
}
dlog.Infof(ctx, "plan: 1/6 process %d chunks", numChunks)
dlog.Infof(ctx, "plan: 2/6 process %d device extents", numDevExts)
dlog.Infof(ctx, "plan: 3/6 process %d nodes", numNodes)
dlog.Infof(ctx, "plan: 4/6 process %d block groups", numBlockGroups)
dlog.Infof(ctx, "plan: 5/6 search for block groups in checksum map (exact)")
dlog.Infof(ctx, "plan: 6/6 search for block groups in checksum map (fuzzy)")
_ctx := ctx
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "1/6")
dlog.Infof(_ctx, "1/6: Processing %d chunks...", numChunks)
for _, devID := range devIDs {
devResults := scanResults[devID]
for _, chunk := range devResults.FoundChunks {
for _, mapping := range chunk.Chunk.Mappings(chunk.Key) {
if err := fs.LV.AddMapping(mapping); err != nil {
dlog.Errorf(ctx, "error: adding chunk: %v", err)
}
}
}
}
dlog.Info(_ctx, "... done processing chunks")
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "2/6")
dlog.Infof(_ctx, "2/6: Processing %d device extents...", numDevExts)
for _, devID := range devIDs {
devResults := scanResults[devID]
for _, ext := range devResults.FoundDevExtents {
if err := fs.LV.AddMapping(ext.DevExt.Mapping(ext.Key)); err != nil {
dlog.Errorf(ctx, "error: adding devext: %v", err)
}
}
}
dlog.Info(_ctx, "... done processing device extents")
// Do the nodes "last" to avoid bloating the mappings table
// too much. (Because nodes are numerous and small, while the
// others are few and large; so it is likely that many of the
// nodes will be subsumed by other things.)
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "3/6")
dlog.Infof(_ctx, "3/6: Processing %d nodes...", numNodes)
for _, devID := range devIDs {
devResults := scanResults[devID]
// Sort them so that progress numbers are predictable.
for _, laddr := range maps.SortedKeys(devResults.FoundNodes) {
for _, paddr := range devResults.FoundNodes[laddr] {
if err := fs.LV.AddMapping(btrfsvol.Mapping{
LAddr: laddr,
PAddr: btrfsvol.QualifiedPhysicalAddr{
Dev: devID,
Addr: paddr,
},
Size: nodeSize,
SizeLocked: false,
}); err != nil {
dlog.Errorf(ctx, "error: adding node ident: %v", err)
}
}
}
}
dlog.Info(_ctx, "... done processing nodes")
// Use block groups to add missing flags (and as a hint to
// combine node entries).
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "4/6")
dlog.Infof(_ctx, "4/6: Processing %d block groups...", numBlockGroups)
// First dedup them, because they change for allocations and
// CoW means that they'll bounce around a lot, so you likely
// have oodles of duplicates?
bgs, err := dedupedBlockGroups(scanResults)
if err != nil {
return err
}
dlog.Infof(ctx, "... de-duplicated to %d block groups", len(bgs))
for _, bgLAddr := range maps.SortedKeys(bgs) {
bg := bgs[bgLAddr]
otherLAddr, otherPAddr := fs.LV.ResolveAny(bg.LAddr, bg.Size)
if otherLAddr < 0 || otherPAddr.Addr < 0 {
dlog.Errorf(ctx, "error: could not pair blockgroup laddr=%v (size=%v flags=%v) with a mapping",
bg.LAddr, bg.Size, bg.Flags)
continue
}
offsetWithinChunk := otherLAddr.Sub(bg.LAddr)
mapping := btrfsvol.Mapping{
LAddr: bg.LAddr,
PAddr: otherPAddr.Add(-offsetWithinChunk),
Size: bg.Size,
SizeLocked: true,
Flags: containers.Optional[btrfsvol.BlockGroupFlags]{
OK: true,
Val: bg.Flags,
},
}
if err := fs.LV.AddMapping(mapping); err != nil {
dlog.Errorf(ctx, "error: adding flags from blockgroup: %v", err)
continue
}
delete(bgs, bgLAddr)
}
dlog.Info(_ctx, "... done processing block groups")
// More than once, I've been tempted to get rid of this exact-search step and just have the fuzzy-search step.
// After all, looking at the timestamps in the log, it's faster per blockgroup! For some background, the big-O
// for each (per blockgroup) looks like:
//
// - exact-search: O(bgSize+physicalBlocks)
// - fuzzy-search: O(bgSize*physicalBlocks) worst-case; O(bgSize*log(physicalBlocks)) expected
//
// The fuzzy-search is only fast because the exact-search is so good at getting `physicalBlocks` down.
// Empirically: if I remove the exact-search step, then the fuzzy-match step is more than an order of magnitude
// slower.
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "5/6")
dlog.Infof(_ctx, "5/6: Searching for %d block groups in checksum map (exact)...", len(bgs))
physicalSums := extractPhysicalSums(scanResults)
logicalSums := extractLogicalSums(ctx, scanResults)
if err := matchBlockGroupSumsExact(ctx, fs, bgs, physicalSums, logicalSums); err != nil {
return err
}
dlog.Info(ctx, "... done searching for exact block groups")
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "6/6")
dlog.Infof(_ctx, "6/6: Searching for %d block groups in checksum map (fuzzy)...", len(bgs))
if err := matchBlockGroupSumsFuzzy(ctx, fs, bgs, physicalSums, logicalSums); err != nil {
return err
}
dlog.Info(_ctx, "... done searching for fuzzy block groups")
ctx = dlog.WithField(_ctx, "btrfs.inspect.rebuild-mappings.process.step", "report")
dlog.Info(_ctx, "report:")
unmappedPhysicalRegions := listUnmappedPhysicalRegions(fs)
var unmappedPhysical btrfsvol.AddrDelta
var numUnmappedPhysical int
for _, devRegions := range unmappedPhysicalRegions {
numUnmappedPhysical += len(devRegions)
for _, region := range devRegions {
unmappedPhysical += region.End.Sub(region.Beg)
}
}
dlog.Infof(ctx, "... %d of unmapped physical space (across %d regions)", textui.IEC(unmappedPhysical, "B"), numUnmappedPhysical)
unmappedLogicalRegions := listUnmappedLogicalRegions(fs, logicalSums)
var unmappedLogical btrfsvol.AddrDelta
for _, region := range unmappedLogicalRegions {
unmappedLogical += region.Size()
}
dlog.Infof(ctx, "... %d of unmapped summed logical space (across %d regions)", textui.IEC(unmappedLogical, "B"), len(unmappedLogicalRegions))
var unmappedBlockGroups btrfsvol.AddrDelta
for _, bg := range bgs {
unmappedBlockGroups += bg.Size
}
dlog.Infof(ctx, "... %d of unmapped block groups (across %d groups)", textui.IEC(unmappedBlockGroups, "B"), len(bgs))
dlog.Info(_ctx, "detailed report:")
for _, devID := range maps.SortedKeys(unmappedPhysicalRegions) {
for _, region := range unmappedPhysicalRegions[devID] {
dlog.Infof(ctx, "... unmapped physical region: dev=%v beg=%v end=%v (size=%v)",
devID, region.Beg, region.End, region.End.Sub(region.Beg))
}
}
for _, region := range unmappedLogicalRegions {
dlog.Infof(ctx, "... umapped summed logical region: beg=%v end=%v (size=%v)",
region.Addr, region.Addr.Add(region.Size()), region.Size())
}
for _, laddr := range maps.SortedKeys(bgs) {
bg := bgs[laddr]
dlog.Infof(ctx, "... umapped block group: beg=%v end=%v (size=%v) flags=%v",
bg.LAddr, bg.LAddr.Add(bg.Size), bg.Size, bg.Flags)
}
return nil
}
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