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package main
import (
"context"
"fmt"
"sync"
"github.com/datawire/dlib/dcontext"
"github.com/datawire/dlib/dlog"
"github.com/jacobsa/fuse"
"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/btrfs/btrfsvol"
)
type Subvolume struct {
FS *btrfs.FS
DeviceName string
Mountpoint string
TreeID btrfs.ObjID
fuseutil.NotImplementedFileSystem
rootOnce sync.Once
rootVal btrfsitem.Root
rootErr error
}
func (sv *Subvolume) Run(ctx context.Context) error {
mount, err := fuse.Mount(
sv.Mountpoint,
fuseutil.NewFileSystemServer(sv),
&fuse.MountConfig{
OpContext: ctx,
ErrorLogger: dlog.StdLogger(ctx, dlog.LogLevelError),
DebugLogger: dlog.StdLogger(ctx, dlog.LogLevelDebug),
FSName: sv.DeviceName,
Subtype: "btrfs",
ReadOnly: true,
})
if err != nil {
return err
}
return mount.Join(dcontext.HardContext(ctx))
}
func (sv *Subvolume) initRoot() {
sv.rootOnce.Do(func() {
sb, err := sv.FS.Superblock()
if err != nil {
sv.rootErr = err
return
}
root, err := sv.FS.TreeLookup(sb.Data.RootTree, btrfs.Key{
ObjectID: sv.TreeID,
ItemType: btrfsitem.ROOT_ITEM_KEY,
Offset: 0,
})
if err != nil {
sv.rootErr = err
return
}
rootBody, ok := root.Body.(btrfsitem.Root)
if !ok {
sv.rootErr = fmt.Errorf("FS_TREE_ ROOT_ITEM has malformed body")
return
}
sv.rootVal = rootBody
})
}
func (sv *Subvolume) getRootInode() (btrfs.ObjID, error) {
sv.initRoot()
return sv.rootVal.RootDirID, sv.rootErr
}
func (sv *Subvolume) getFSTree() (btrfsvol.LogicalAddr, error) {
sv.initRoot()
return sv.rootVal.ByteNr, sv.rootErr
}
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 {}
func (sv *Subvolume) GetInodeAttributes(ctx 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)
}
tree, err := sv.getFSTree()
if err != nil {
return err
}
item, err := sv.FS.TreeLookup(tree, btrfs.Key{
ObjectID: btrfs.ObjID(op.Inode),
ItemType: btrfsitem.INODE_ITEM_KEY,
Offset: 0,
})
if err != nil {
return err
}
itemBody, ok := item.Body.(btrfsitem.Inode)
if !ok {
return fmt.Errorf("malformed inode")
}
op.Attributes = 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),
}
return nil
}
// func (sv *Subvolume) ForgetInode(_ context.Context, op *fuseops.ForgetInodeOp) error {}
// func (sv *Subvolume) BatchForget(_ context.Context, op *fuseops.BatchForgetOp) error {}
// func (sv *Subvolume) OpenDir(_ context.Context, op *fuseops.OpenDirOp) error {}
// func (sv *Subvolume) ReadDir(_ context.Context, op *fuseops.ReadDirOp) error {}
// func (sv *Subvolume) ReleaseDirHandle(_ context.Context, op *fuseops.ReleaseDirHandleOp) error {}
// func (sv *Subvolume) OpenFile(_ context.Context, op *fuseops.OpenFileOp) error {}
// func (sv *Subvolume) ReadFile(_ context.Context, op *fuseops.ReadFileOp) error {}
// func (sv *Subvolume) ReleaseFileHandle(_ context.Context, op *fuseops.ReleaseFileHandleOp) error {}
// func (sv *Subvolume) ReadSymlink(_ context.Context, op *fuseops.ReadSymlinkOp) error {}
// func (sv *Subvolume) GetXattr(_ context.Context, op *fuseops.GetXattrOp) error {}
// func (sv *Subvolume) ListXattr(_ context.Context, op *fuseops.ListXattrOp) error {}
// func (sv *Subvolume) Destroy() {}
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