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package btrfs
import (
"fmt"
"reflect"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsvol"
"lukeshu.com/btrfs-tools/pkg/util"
)
type FS struct {
lv btrfsvol.LogicalVolume[*Device]
cacheSuperblocks []*util.Ref[PhysicalAddr, Superblock]
cacheSuperblock *util.Ref[PhysicalAddr, Superblock]
}
var _ util.File[LogicalAddr] = (*FS)(nil)
func (fs *FS) AddDevice(dev *Device) error {
sb, err := dev.Superblock()
if err != nil {
return err
}
return fs.lv.AddPhysicalVolume(sb.Data.DevItem.DevUUID, dev)
}
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.Data.FSUUID)
fs.lv.SetName(name)
return name
}
func (fs *FS) Size() (LogicalAddr, error) {
return fs.lv.Size()
}
func (fs *FS) ReadAt(p []byte, off LogicalAddr) (int, error) {
return fs.lv.ReadAt(p, off)
}
func (fs *FS) WriteAt(p []byte, off LogicalAddr) (int, error) {
return fs.lv.WriteAt(p, off)
}
func (fs *FS) Resolve(laddr LogicalAddr) (paddrs map[QualifiedPhysicalAddr]struct{}, maxlen AddrDelta) {
return fs.lv.Resolve(laddr)
}
func (fs *FS) UnResolve(paddr QualifiedPhysicalAddr) LogicalAddr {
return fs.lv.UnResolve(paddr)
}
func (fs *FS) Devices() []*Device {
return fs.lv.PhysicalVolumes()
}
func (fs *FS) Superblocks() ([]*util.Ref[PhysicalAddr, Superblock], error) {
if fs.cacheSuperblocks != nil {
return fs.cacheSuperblocks, nil
}
var ret []*util.Ref[PhysicalAddr, Superblock]
for _, dev := range fs.lv.PhysicalVolumes() {
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() (*util.Ref[PhysicalAddr, Superblock], error) {
if fs.cacheSuperblock != nil {
return fs.cacheSuperblock, nil
}
sbs, err := fs.Superblocks()
if err != nil {
return nil, err
}
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 {
// 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]
return sbs[0], nil
}
func (fs *FS) Init() error {
fs.lv.ClearMappings()
for _, dev := range fs.lv.PhysicalVolumes() {
sbs, err := dev.Superblocks()
if err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
a := sbs[0].Data
a.Checksum = CSum{}
a.Self = 0
for i, sb := range sbs[1:] {
b := sb.Data
b.Checksum = CSum{}
b.Self = 0
if !reflect.DeepEqual(a, b) {
return fmt.Errorf("file %q: superblock %v disagrees with superblock 0",
dev.Name(), i+1)
}
}
sb := sbs[0]
syschunks, err := sb.Data.ParseSysChunkArray()
if err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
for _, chunk := range syschunks {
for _, stripe := range chunk.Chunk.Stripes {
if err := fs.lv.AddMapping(
LogicalAddr(chunk.Key.Offset),
QualifiedPhysicalAddr{
Dev: stripe.DeviceUUID,
Addr: stripe.Offset,
},
chunk.Chunk.Head.Size,
&chunk.Chunk.Head.Type,
); err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
}
}
if err := fs.WalkTree(sb.Data.ChunkTree, WalkTreeHandler{
Item: func(_ WalkTreePath, item Item) error {
if item.Head.Key.ItemType != btrfsitem.CHUNK_ITEM_KEY {
return nil
}
body := item.Body.(btrfsitem.Chunk)
for _, stripe := range body.Stripes {
if err := fs.lv.AddMapping(
LogicalAddr(item.Head.Key.Offset),
QualifiedPhysicalAddr{
Dev: stripe.DeviceUUID,
Addr: stripe.Offset,
},
body.Head.Size,
&body.Head.Type,
); err != nil {
return fmt.Errorf("file %q: %w", dev.Name(), err)
}
}
return nil
},
}); err != nil {
return err
}
}
return nil
}
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