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package main
import (
"context"
"fmt"
"sync/atomic"
"syscall"
"github.com/jacobsa/fuse/fuseops"
"github.com/jacobsa/fuse/fuseutil"
"lukeshu.com/btrfs-tools/pkg/btrfs"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
"lukeshu.com/btrfs-tools/pkg/util"
)
type dirState struct {
Dir *dir
}
type subvolumeFUSE struct {
fuseutil.NotImplementedFileSystem
lastHandle uint64
dirHandles util.SyncMap[uint64, *dirState]
}
func (sv *subvolumeFUSE) init() {}
func inodeItemToFUSE(itemBody btrfsitem.Inode) fuseops.InodeAttributes {
return fuseops.InodeAttributes{
Size: uint64(itemBody.Size),
Nlink: uint32(itemBody.NLink),
Mode: uint32(itemBody.Mode),
//RDev: itemBody.Rdev, // jacobsa/fuse doesn't expose rdev
Atime: itemBody.ATime.ToStd(),
Mtime: itemBody.MTime.ToStd(),
Ctime: itemBody.CTime.ToStd(),
//Crtime: itemBody.OTime,
Uid: uint32(itemBody.UID),
Gid: uint32(itemBody.GID),
}
}
func (sv *Subvolume) StatFS(_ context.Context, op *fuseops.StatFSOp) error {
// See linux.git/fs/btrfs/super.c:btrfs_statfs()
sb, err := sv.FS.Superblock()
if err != nil {
return err
}
op.IoSize = sb.Data.SectorSize
op.BlockSize = sb.Data.SectorSize
op.Blocks = sb.Data.TotalBytes / uint64(sb.Data.SectorSize) // TODO: adjust for RAID type
//op.BlocksFree = TODO
// btrfs doesn't have a fixed number of inodes
op.Inodes = 0
op.InodesFree = 0
// jacobsa/fuse doesn't expose namelen, instead hard-coding it
// to 255. Which is fine by us, because that's what it is for
// btrfs.
return nil
}
func (sv *Subvolume) LookUpInode(_ context.Context, op *fuseops.LookUpInodeOp) error {
if op.Parent == fuseops.RootInodeID {
parent, err := sv.getRootInode()
if err != nil {
return err
}
op.Parent = fuseops.InodeID(parent)
}
dir, err := sv.loadDir(btrfs.ObjID(op.Parent))
if err != nil {
return err
}
entry, ok := dir.ChildrenByName[op.Name]
if !ok {
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)
}
inodeItem, err := sv.loadInode(entry.Location.ObjectID)
if err != nil {
return err
}
op.Entry = fuseops.ChildInodeEntry{
Child: fuseops.InodeID(entry.Location.ObjectID),
Generation: fuseops.GenerationNumber(inodeItem.Sequence),
Attributes: inodeItemToFUSE(inodeItem),
}
return nil
}
func (sv *Subvolume) GetInodeAttributes(_ context.Context, op *fuseops.GetInodeAttributesOp) error {
if op.Inode == fuseops.RootInodeID {
inode, err := sv.getRootInode()
if err != nil {
return err
}
op.Inode = fuseops.InodeID(inode)
}
inodeItem, err := sv.loadInode(btrfs.ObjID(op.Inode))
if err != nil {
return err
}
op.Attributes = inodeItemToFUSE(inodeItem)
return nil
}
func (sv *Subvolume) OpenDir(_ context.Context, op *fuseops.OpenDirOp) error {
if op.Inode == fuseops.RootInodeID {
inode, err := sv.getRootInode()
if err != nil {
return err
}
op.Inode = fuseops.InodeID(inode)
}
dir, err := sv.loadDir(btrfs.ObjID(op.Inode))
if err != nil {
return err
}
handle := atomic.AddUint64(&sv.lastHandle, 1)
sv.dirHandles.Store(handle, &dirState{
Dir: dir,
})
op.Handle = fuseops.HandleID(handle)
return nil
}
func (sv *Subvolume) ReadDir(_ context.Context, op *fuseops.ReadDirOp) error {
state, ok := sv.dirHandles.Load(uint64(op.Handle))
if !ok {
return syscall.EBADF
}
indexes := util.SortedMapKeys(state.Dir.ChildrenByIndex)
origOffset := op.Offset
for _, index := range indexes {
if index < uint64(origOffset) {
continue
}
entry := state.Dir.ChildrenByIndex[index]
n := fuseutil.WriteDirent(op.Dst[op.BytesRead:], fuseutil.Dirent{
Offset: fuseops.DirOffset(index + 1),
Inode: fuseops.InodeID(entry.Location.ObjectID),
Name: string(entry.Name),
Type: map[btrfsitem.FileType]fuseutil.DirentType{
btrfsitem.FT_UNKNOWN: fuseutil.DT_Unknown,
btrfsitem.FT_REG_FILE: fuseutil.DT_File,
btrfsitem.FT_DIR: fuseutil.DT_Directory,
btrfsitem.FT_CHRDEV: fuseutil.DT_Char,
btrfsitem.FT_BLKDEV: fuseutil.DT_Block,
btrfsitem.FT_FIFO: fuseutil.DT_FIFO,
btrfsitem.FT_SOCK: fuseutil.DT_Socket,
btrfsitem.FT_SYMLINK: fuseutil.DT_Link,
}[entry.Type],
})
if n == 0 {
break
}
op.BytesRead += n
}
return nil
}
func (sv *Subvolume) ReleaseDirHandle(_ context.Context, op *fuseops.ReleaseDirHandleOp) error {
_, ok := sv.dirHandles.LoadAndDelete(uint64(op.Handle))
if !ok {
return syscall.EBADF
}
return nil
}
func (sv *Subvolume) OpenFile(_ context.Context, op *fuseops.OpenFileOp) error { return syscall.ENOSYS }
func (sv *Subvolume) ReadFile(_ context.Context, op *fuseops.ReadFileOp) error { return syscall.ENOSYS }
func (sv *Subvolume) ReleaseFileHandle(_ context.Context, op *fuseops.ReleaseFileHandleOp) error {
return syscall.ENOSYS
}
func (sv *Subvolume) ReadSymlink(_ context.Context, op *fuseops.ReadSymlinkOp) error {
return syscall.ENOSYS
}
func (sv *Subvolume) GetXattr(_ context.Context, op *fuseops.GetXattrOp) error { return syscall.ENOSYS }
func (sv *Subvolume) ListXattr(_ context.Context, op *fuseops.ListXattrOp) error {
return syscall.ENOSYS
}
func (sv *Subvolume) Destroy() {}
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