1 files changed, 187 insertions, 0 deletions
diff --git a/pkg/btrfs/io2_lv.go b/pkg/btrfs/io2_lv.go
new file mode 100644
index 0000000..0564066
--- /dev/null
+++ b/pkg/btrfs/io2_lv.go
@@ -0,0 +1,187 @@
+package btrfs
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/datawire/dlib/derror"
+
+	"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
+	"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsvol"
+	"lukeshu.com/btrfs-tools/pkg/util"
+)
+
+type FS struct {
+	// You should probably not access .LV directly, except when
+	// implementing special things like fsck.
+	LV btrfsvol.LogicalVolume[*Device]
+
+	cacheSuperblocks []*util.Ref[btrfsvol.PhysicalAddr, Superblock]
+	cacheSuperblock  *util.Ref[btrfsvol.PhysicalAddr, Superblock]
+}
+
+var _ util.File[btrfsvol.LogicalAddr] = (*FS)(nil)
+
+func (fs *FS) AddDevice(dev *Device) error {
+	sb, err := dev.Superblock()
+	if err != nil {
+		return err
+	}
+	if err := fs.LV.AddPhysicalVolume(sb.Data.DevItem.DevID, dev); err != nil {
+		return err
+	}
+	fs.cacheSuperblocks = nil
+	fs.cacheSuperblock = nil
+	if err := fs.initDev(sb); err != nil {
+		return 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.Data.FSUUID)
+	fs.LV.SetName(name)
+	return name
+}
+
+func (fs *FS) Size() (btrfsvol.LogicalAddr, error) {
+	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) Resolve(laddr btrfsvol.LogicalAddr) (paddrs map[btrfsvol.QualifiedPhysicalAddr]struct{}, maxlen btrfsvol.AddrDelta) {
+	return fs.LV.Resolve(laddr)
+}
+
+func (fs *FS) Superblocks() ([]*util.Ref[btrfsvol.PhysicalAddr, Superblock], error) {
+	if fs.cacheSuperblocks != nil {
+		return fs.cacheSuperblocks, nil
+	}
+	var ret []*util.Ref[btrfsvol.PhysicalAddr, 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() (*util.Ref[btrfsvol.PhysicalAddr, 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]
+	return sbs[0], nil
+}
+
+func (fs *FS) ReInit() 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(sb); err != nil {
+			return fmt.Errorf("file %q: %w", dev.Name(), err)
+		}
+	}
+	return nil
+}
+
+func (fs *FS) initDev(sb *util.Ref[btrfsvol.PhysicalAddr, Superblock]) error {
+	syschunks, err := sb.Data.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
+			}
+		}
+	}
+	if err := fs.TreeWalk(sb.Data.ChunkTree, TreeWalkHandler{
+		Item: func(_ TreePath, item Item) error {
+			if item.Head.Key.ItemType != btrfsitem.CHUNK_ITEM_KEY {
+				return nil
+			}
+			for _, mapping := range item.Body.(btrfsitem.Chunk).Mappings(item.Head.Key) {
+				if err := fs.LV.AddMapping(mapping); err != nil {
+					return err
+				}
+			}
+			return nil
+		},
+	}); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (fs *FS) Close() error {
+	var errs derror.MultiError
+	for _, dev := range fs.LV.PhysicalVolumes() {
+		if err := dev.Close(); err != nil && err == nil {
+			errs = append(errs, err)
+		}
+	}
+	if errs != nil {
+		return errs
+	}
+	return nil
+}
+
+var _ io.Closer = (*FS)(nil)