subvolumes working, kinda

7 files changed, 152 insertions, 55 deletions

diff --git a/cmd/btrfs-mount/main.go b/cmd/btrfs-mount/main.go
index 64cae30..4451e7a 100644
--- a/cmd/btrfs-mount/main.go
+++ b/cmd/btrfs-mount/main.go
@@ -68,7 +68,7 @@ func Main(ctx context.Context, mountpoint string, imgfilenames ...string) (err e
 		}
 		return fuse.Unmount(os.Args[1])
 	})
-	grp.Go("main", func(ctx context.Context) error {
+	grp.Go("mount", func(ctx context.Context) error {
 		defer atomic.StoreUint32(&mounted, 0)
 		rootSubvol := &Subvolume{
 			Subvolume: btrfs.Subvolume{
@@ -78,7 +78,7 @@ func Main(ctx context.Context, mountpoint string, imgfilenames ...string) (err e
 			DeviceName: tryAbs(imgfilenames[0]),
 			Mountpoint: mountpoint,
 		}
-		return rootSubvol.Run(ctx)
+		return rootSubvol.Run(ctx, false)
 	})
 	return grp.Wait()
 }
diff --git a/cmd/btrfs-mount/subvol_fuse.go b/cmd/btrfs-mount/subvol_fuse.go
index 3a22c9a..522da85 100644
--- a/cmd/btrfs-mount/subvol_fuse.go
+++ b/cmd/btrfs-mount/subvol_fuse.go
@@ -2,11 +2,16 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"io"
+	"path/filepath"
+	"sync"
 	"sync/atomic"
 	"syscall"
 
 	"github.com/datawire/dlib/dcontext"
+	"github.com/datawire/dlib/dgroup"
 	"github.com/datawire/dlib/dlog"
 	"github.com/jacobsa/fuse"
 	"github.com/jacobsa/fuse/fuseops"
@@ -14,6 +19,7 @@ import (
 
 	"lukeshu.com/btrfs-tools/pkg/btrfs"
 	"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
+	"lukeshu.com/btrfs-tools/pkg/linux"
 	"lukeshu.com/btrfs-tools/pkg/util"
 )
 
@@ -34,13 +40,16 @@ type Subvolume struct {
 	lastHandle  uint64
 	dirHandles  util.SyncMap[fuseops.HandleID, *dirState]
 	fileHandles util.SyncMap[fuseops.HandleID, *fileState]
+
+	subvolMu sync.Mutex
+	subvols  map[string]struct{}
+	grp      *dgroup.Group
 }
 
-func (sv *Subvolume) Run(ctx context.Context) error {
-	mount, err := fuse.Mount(
-		sv.Mountpoint,
-		fuseutil.NewFileSystemServer(sv),
-		&fuse.MountConfig{
+func (sv *Subvolume) Run(ctx context.Context, isSubvol bool) error {
+	sv.grp = dgroup.NewGroup(ctx, dgroup.GroupConfig{})
+	sv.grp.Go("self", func(ctx context.Context) error {
+		cfg := &fuse.MountConfig{
 			OpContext:   ctx,
 			ErrorLogger: dlog.StdLogger(ctx, dlog.LogLevelError),
 			DebugLogger: dlog.StdLogger(ctx, dlog.LogLevelDebug),
@@ -49,11 +58,24 @@ func (sv *Subvolume) Run(ctx context.Context) error {
 			Subtype: "btrfs",
 
 			ReadOnly: true,
-		})
-	if err != nil {
-		return err
-	}
-	return mount.Join(dcontext.HardContext(ctx))
+
+			Options: map[string]string{
+				"allow_other": "",
+			},
+		}
+		if isSubvol {
+			//cfg.Options["nonempty"] = ""
+		}
+		mount, err := fuse.Mount(
+			sv.Mountpoint,
+			fuseutil.NewFileSystemServer(sv),
+			cfg)
+		if err != nil {
+			return err
+		}
+		return mount.Join(dcontext.HardContext(ctx))
+	})
+	return sv.grp.Wait()
 }
 
 func (sv *Subvolume) newHandle() fuseops.HandleID {
@@ -75,6 +97,54 @@ func inodeItemToFUSE(itemBody btrfsitem.Inode) fuseops.InodeAttributes {
 	}
 }
 
+func (sv *Subvolume) LoadDir(inode btrfs.ObjID) (val *btrfs.Dir, err error) {
+	val, err = sv.Subvolume.LoadDir(inode)
+	if val != nil {
+		haveSubvolumes := false
+		for _, index := range util.SortedMapKeys(val.ChildrenByIndex) {
+			entry := val.ChildrenByIndex[index]
+			if entry.Location.ItemType == btrfsitem.ROOT_ITEM_KEY {
+				haveSubvolumes = true
+				break
+			}
+		}
+		if haveSubvolumes {
+			abspath, _err := val.AbsPath()
+			if _err != nil {
+				return
+			}
+			sv.subvolMu.Lock()
+			for _, index := range util.SortedMapKeys(val.ChildrenByIndex) {
+				entry := val.ChildrenByIndex[index]
+				if entry.Location.ItemType != btrfsitem.ROOT_ITEM_KEY {
+					continue
+				}
+				if sv.subvols == nil {
+					sv.subvols = make(map[string]struct{})
+				}
+				subMountpoint := filepath.Join(abspath, string(entry.Name))
+				if _, alreadyMounted := sv.subvols[subMountpoint]; !alreadyMounted {
+					sv.subvols[subMountpoint] = struct{}{}
+					workerName := fmt.Sprintf("%d-%s", val.Inode, filepath.Base(subMountpoint))
+					sv.grp.Go(workerName, func(ctx context.Context) error {
+						subSv := &Subvolume{
+							Subvolume: btrfs.Subvolume{
+								FS:     sv.FS,
+								TreeID: entry.Location.ObjectID,
+							},
+							DeviceName: sv.DeviceName,
+							Mountpoint: filepath.Join(sv.Mountpoint, subMountpoint[1:]),
+						}
+						return subSv.Run(ctx, true)
+					})
+				}
+			}
+			sv.subvolMu.Unlock()
+		}
+	}
+	return
+}
+
 func (sv *Subvolume) StatFS(_ context.Context, op *fuseops.StatFSOp) error {
 	// See linux.git/fs/btrfs/super.c:btrfs_statfs()
 	sb, err := sv.FS.Superblock()
@@ -116,7 +186,16 @@ func (sv *Subvolume) LookUpInode(_ context.Context, op *fuseops.LookUpInodeOp) e
 		return syscall.ENOENT
 	}
 	if entry.Location.ItemType != btrfsitem.INODE_ITEM_KEY {
-		return fmt.Errorf("child %q is not an inode: %w", op.Name, syscall.ENOSYS)
+		op.Entry = fuseops.ChildInodeEntry{
+			Child: 2, // an inode number that a real file will never have
+			Attributes: fuseops.InodeAttributes{
+				Nlink: 1,
+				Mode:  uint32(linux.ModeFmtDir | 0700),
+				//Uid:   1000, // TODO
+				//Gid:   1000, // TODO
+			},
+		}
+		return nil
 	}
 	bareInode, err := sv.LoadBareInode(entry.Location.ObjectID)
 	if err != nil {
@@ -240,6 +319,9 @@ func (sv *Subvolume) ReadFile(_ context.Context, op *fuseops.ReadFileOp) error {
 
 	var err error
 	op.BytesRead, err = state.File.ReadAt(dat, op.Offset)
+	if errors.Is(err, io.EOF) {
+		err = nil
+	}
 
 	return err
 }
diff --git a/pkg/btrfs/btrfsitem/item_inoderef.go b/pkg/btrfs/btrfsitem/item_inoderef.go
index 78dd677..2c26df6 100644
--- a/pkg/btrfs/btrfsitem/item_inoderef.go
+++ b/pkg/btrfs/btrfsitem/item_inoderef.go
@@ -4,36 +4,9 @@ import (
 	"lukeshu.com/btrfs-tools/pkg/binstruct"
 )
 
-type InodeRefList []InodeRef // INODE_REF=12
-
-func (o *InodeRefList) UnmarshalBinary(dat []byte) (int, error) {
-	*o = nil
-	n := 0
-	for n < len(dat) {
-		var ref InodeRef
-		_n, err := binstruct.Unmarshal(dat, &ref)
-		n += _n
-		if err != nil {
-			return n, err
-		}
-		*o = append(*o, ref)
-	}
-	return n, nil
-}
-
-func (o InodeRefList) MarshalBinary() ([]byte, error) {
-	var ret []byte
-	for _, ref := range o {
-		bs, err := binstruct.Marshal(ref)
-		ret = append(ret, bs...)
-		if err != nil {
-			return ret, err
-		}
-	}
-	return ret, nil
-}
-
-type InodeRef struct {
+// key.objectid = inode number of the file
+// key.offset = inode number of the parent file
+type InodeRef struct { // INODE_REF=12
 	Index         int64  `bin:"off=0x0, siz=0x8"`
 	NameLen       uint16 `bin:"off=0x8, siz=0x2"` // [ignored-when-writing]
 	binstruct.End `bin:"off=0xa"`
diff --git a/pkg/btrfs/btrfsitem/items.txt b/pkg/btrfs/btrfsitem/items.txt
index 2820788..7898775 100644
--- a/pkg/btrfs/btrfsitem/items.txt
+++ b/pkg/btrfs/btrfsitem/items.txt
@@ -12,7 +12,7 @@ FREE_SPACE_BITMAP=200 FreeSpaceBitmap
 FREE_SPACE_EXTENT=199 Empty
 FREE_SPACE_INFO=198 FreeSpaceInfo
 INODE_ITEM=1 Inode
-INODE_REF=12 InodeRefList
+INODE_REF=12 InodeRef
 METADATA_ITEM=169 Metadata
 ORPHAN_ITEM=48 Empty
 PERSISTENT_ITEM=249 DevStats
diff --git a/pkg/btrfs/btrfsitem/items_gen.go b/pkg/btrfs/btrfsitem/items_gen.go
index 030202b..b5b64bd 100644
--- a/pkg/btrfs/btrfsitem/items_gen.go
+++ b/pkg/btrfs/btrfsitem/items_gen.go
@@ -55,7 +55,7 @@ var keytype2gotype = map[Type]reflect.Type{
 	FREE_SPACE_EXTENT_KEY:    reflect.TypeOf(Empty{}),
 	FREE_SPACE_INFO_KEY:      reflect.TypeOf(FreeSpaceInfo{}),
 	INODE_ITEM_KEY:           reflect.TypeOf(Inode{}),
-	INODE_REF_KEY:            reflect.TypeOf(InodeRefList{}),
+	INODE_REF_KEY:            reflect.TypeOf(InodeRef{}),
 	METADATA_ITEM_KEY:        reflect.TypeOf(Metadata{}),
 	ORPHAN_ITEM_KEY:          reflect.TypeOf(Empty{}),
 	PERSISTENT_ITEM_KEY:      reflect.TypeOf(DevStats{}),
@@ -89,7 +89,7 @@ func (FreeSpaceBitmap) isItem() {}
 func (FreeSpaceHeader) isItem() {}
 func (FreeSpaceInfo) isItem()   {}
 func (Inode) isItem()           {}
-func (InodeRefList) isItem()    {}
+func (InodeRef) isItem()        {}
 func (Metadata) isItem()        {}
 func (Root) isItem()            {}
 func (RootRef) isItem()         {}
diff --git a/pkg/btrfs/io3_fs.go b/pkg/btrfs/io3_fs.go
index a418b05..75b973b 100644
--- a/pkg/btrfs/io3_fs.go
+++ b/pkg/btrfs/io3_fs.go
@@ -3,6 +3,7 @@ package btrfs
 import (
 	"fmt"
 	"io"
+	"path/filepath"
 	"reflect"
 	"sort"
 	"sync"
@@ -25,10 +26,17 @@ type FullInode struct {
 	OtherItems []Item
 }
 
+type InodeRef struct {
+	Inode ObjID
+	btrfsitem.InodeRef
+}
+
 type Dir struct {
 	FullInode
+	DotDot          *InodeRef
 	ChildrenByName  map[string]btrfsitem.DirEntry
 	ChildrenByIndex map[uint64]btrfsitem.DirEntry
+	SV              *Subvolume
 }
 
 type FileExtent struct {
@@ -39,7 +47,7 @@ type FileExtent struct {
 type File struct {
 	FullInode
 	Extents []FileExtent
-	FS      *FS
+	SV      *Subvolume
 }
 
 type Subvolume struct {
@@ -182,6 +190,7 @@ func (sv *Subvolume) LoadDir(inode ObjID) (*Dir, error) {
 			return
 		}
 		val.FullInode = *fullInode
+		val.SV = sv
 		val.populate()
 		return
 	})
@@ -197,7 +206,17 @@ func (ret *Dir) populate() {
 	for _, item := range ret.OtherItems {
 		switch item.Head.Key.ItemType {
 		case btrfsitem.INODE_REF_KEY:
-			// TODO
+			ref := InodeRef{
+				Inode:    ObjID(item.Head.Key.Offset),
+				InodeRef: item.Body.(btrfsitem.InodeRef),
+			}
+			if ret.DotDot != nil {
+				if !reflect.DeepEqual(ref, *ret.DotDot) {
+					ret.Errs = append(ret.Errs, fmt.Errorf("multiple INODE_REF items on a directory"))
+				}
+				continue
+			}
+			ret.DotDot = &ref
 		case btrfsitem.DIR_ITEM_KEY:
 			body := item.Body.(btrfsitem.DirEntries)
 			if len(body) != 1 {
@@ -265,6 +284,28 @@ func (ret *Dir) populate() {
 	return
 }
 
+func (dir *Dir) AbsPath() (string, error) {
+	rootInode, err := dir.SV.GetRootInode()
+	if err != nil {
+		return "", err
+	}
+	if rootInode == dir.Inode {
+		return "/", nil
+	}
+	if dir.DotDot == nil {
+		return "", fmt.Errorf("missing .. entry in dir inode %v", dir.Inode)
+	}
+	parent, err := dir.SV.LoadDir(dir.DotDot.Inode)
+	if err != nil {
+		return "", err
+	}
+	parentName, err := parent.AbsPath()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(parentName, string(dir.DotDot.Name)), nil
+}
+
 func (sv *Subvolume) LoadFile(inode ObjID) (*File, error) {
 	val := sv.fileCache.GetOrElse(inode, func() (val *File) {
 		val = new(File)
@@ -274,7 +315,7 @@ func (sv *Subvolume) LoadFile(inode ObjID) (*File, error) {
 			return
 		}
 		val.FullInode = *fullInode
-		val.FS = sv.FS
+		val.SV = sv
 		val.populate()
 		return
 	})
@@ -370,12 +411,15 @@ func (file *File) maybeShortReadAt(dat []byte, off int64) (int, error) {
 		case btrfsitem.FILE_EXTENT_INLINE:
 			return copy(dat, extent.BodyInline[offsetWithinExt:offsetWithinExt+readSize]), nil
 		case btrfsitem.FILE_EXTENT_REG, btrfsitem.FILE_EXTENT_PREALLOC:
-			return file.FS.ReadAt(dat[:readSize],
+			return file.SV.FS.ReadAt(dat[:readSize],
 				extent.BodyExtent.DiskByteNr.
 					Add(extent.BodyExtent.Offset).
 					Add(btrfsvol.AddrDelta(offsetWithinExt)))
 		}
 	}
+	if file.InodeItem != nil && off >= file.InodeItem.Size {
+		return 0, io.EOF
+	}
 	return 0, fmt.Errorf("read: could not map position %v", off)
 }
 
diff --git a/pkg/btrfsmisc/print_tree.go b/pkg/btrfsmisc/print_tree.go
index 61c5423..c03cb4a 100644
--- a/pkg/btrfsmisc/print_tree.go
+++ b/pkg/btrfsmisc/print_tree.go
@@ -57,11 +57,9 @@ func PrintTree(fs *btrfs.FS, root btrfsvol.LogicalAddr) error {
 				fmt.Printf("\t\tctime %v\n", fmtTime(body.CTime))
 				fmt.Printf("\t\tmtime %v\n", fmtTime(body.MTime))
 				fmt.Printf("\t\totime %v\n", fmtTime(body.OTime))
-			case btrfsitem.InodeRefList:
-				for _, ref := range body {
-					fmt.Printf("\t\tindex %v namelen %v name: %s\n",
-						ref.Index, ref.NameLen, ref.Name)
-				}
+			case btrfsitem.InodeRef:
+				fmt.Printf("\t\tindex %v namelen %v name: %s\n",
+					body.Index, body.NameLen, body.Name)
 			//case btrfsitem.INODE_EXTREF_KEY:
 			//	// TODO
 			case btrfsitem.DirEntries: