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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfs
import (
"context"
"fmt"
"io"
"github.com/datawire/dlib/derror"
"github.com/datawire/dlib/dlog"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfstree"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
"git.lukeshu.com/btrfs-progs-ng/lib/diskio"
)
type FS struct {
// You should probably not access .LV directly, except when
// implementing special things like fsck.
LV btrfsvol.LogicalVolume[*Device]
cacheSuperblocks []*diskio.Ref[btrfsvol.PhysicalAddr, btrfstree.Superblock]
cacheSuperblock *btrfstree.Superblock
cacheObjID2UUID map[btrfsprim.ObjID]btrfsprim.UUID
cacheUUID2ObjID map[btrfsprim.UUID]btrfsprim.ObjID
cacheTreeParent map[btrfsprim.ObjID]btrfsprim.UUID
}
var _ diskio.File[btrfsvol.LogicalAddr] = (*FS)(nil)
func (fs *FS) AddDevice(ctx context.Context, dev *Device) error {
sb, err := dev.Superblock()
if err != nil {
return err
}
if err := fs.LV.AddPhysicalVolume(sb.DevItem.DevID, dev); err != nil {
return err
}
fs.cacheSuperblocks = nil
fs.cacheSuperblock = nil
if err := fs.initDev(ctx, *sb); err != nil {
dlog.Errorf(ctx, "error: AddDevice: %q: %v", dev.Name(), err)
}
return nil
}
func (fs *FS) Name() string {
if name := fs.LV.Name(); name != "" {
return name
}
sb, err := fs.Superblock()
if err != nil {
return fmt.Sprintf("fs_uuid=%v", "(unreadable)")
}
name := fmt.Sprintf("fs_uuid=%v", sb.FSUUID)
fs.LV.SetName(name)
return name
}
func (fs *FS) Size() btrfsvol.LogicalAddr {
return fs.LV.Size()
}
func (fs *FS) ReadAt(p []byte, off btrfsvol.LogicalAddr) (int, error) {
return fs.LV.ReadAt(p, off)
}
func (fs *FS) WriteAt(p []byte, off btrfsvol.LogicalAddr) (int, error) {
return fs.LV.WriteAt(p, off)
}
func (fs *FS) Superblocks() ([]*diskio.Ref[btrfsvol.PhysicalAddr, btrfstree.Superblock], error) {
if fs.cacheSuperblocks != nil {
return fs.cacheSuperblocks, nil
}
var ret []*diskio.Ref[btrfsvol.PhysicalAddr, btrfstree.Superblock]
devs := fs.LV.PhysicalVolumes()
if len(devs) == 0 {
return nil, fmt.Errorf("no devices")
}
for _, dev := range devs {
sbs, err := dev.Superblocks()
if err != nil {
return nil, fmt.Errorf("file %q: %w", dev.Name(), err)
}
ret = append(ret, sbs...)
}
fs.cacheSuperblocks = ret
return ret, nil
}
func (fs *FS) Superblock() (*btrfstree.Superblock, error) {
if fs.cacheSuperblock != nil {
return fs.cacheSuperblock, nil
}
sbs, err := fs.Superblocks()
if err != nil {
return nil, err
}
if len(sbs) == 0 {
return nil, fmt.Errorf("no superblocks")
}
fname := ""
sbi := 0
for i, sb := range sbs {
if sb.File.Name() != fname {
fname = sb.File.Name()
sbi = 0
} else {
sbi++
}
if err := sb.Data.ValidateChecksum(); err != nil {
return nil, fmt.Errorf("file %q superblock %v: %w", sb.File.Name(), sbi, err)
}
if i > 0 {
// FIXME(lukeshu): This is probably wrong, but
// lots of my multi-device code is probably
// wrong.
if !sb.Data.Equal(sbs[0].Data) {
return nil, fmt.Errorf("file %q superblock %v and file %q superblock %v disagree",
sbs[0].File.Name(), 0,
sb.File.Name(), sbi)
}
}
}
fs.cacheSuperblock = &sbs[0].Data
return &sbs[0].Data, nil
}
func (fs *FS) ReInit(ctx context.Context) error {
fs.LV.ClearMappings()
for _, dev := range fs.LV.PhysicalVolumes() {
sb, err := dev.Superblock()
if err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
if err := fs.initDev(ctx, *sb); err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
}
return nil
}
func (fs *FS) initDev(ctx context.Context, sb btrfstree.Superblock) error {
syschunks, err := sb.ParseSysChunkArray()
if err != nil {
return err
}
for _, chunk := range syschunks {
for _, mapping := range chunk.Chunk.Mappings(chunk.Key) {
if err := fs.LV.AddMapping(mapping); err != nil {
return err
}
}
}
var errs derror.MultiError
fs.TreeWalk(ctx, btrfsprim.CHUNK_TREE_OBJECTID,
func(err *btrfstree.TreeError) {
errs = append(errs, err)
},
btrfstree.TreeWalkHandler{
Item: func(_ btrfstree.TreePath, item btrfstree.Item) error {
if item.Key.ItemType != btrfsitem.CHUNK_ITEM_KEY {
return nil
}
switch itemBody := item.Body.(type) {
case *btrfsitem.Chunk:
for _, mapping := range itemBody.Mappings(item.Key) {
if err := fs.LV.AddMapping(mapping); err != nil {
return err
}
}
case *btrfsitem.Error:
// do nothing
default:
// This is a panic because the item decoder should not emit CHUNK_ITEM items as
// anything but btrfsitem.Chunk or btrfsitem.Error without this code also being
// updated.
panic(fmt.Errorf("should not happen: CHUNK_ITEM has unexpected item type: %T", itemBody))
}
return nil
},
},
)
if len(errs) > 0 {
return errs
}
return nil
}
func (fs *FS) Close() error {
return fs.LV.Close()
}
var _ io.Closer = (*FS)(nil)
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