message: rafs/v6: implement get symlink for V6 inode
diff: @@ -498,7 +498,15 @@ impl RafsInode for OndiskInodeWrapper {
  /// # Safety
  /// It depends on Self::validate() to ensure valid memory layout.
  fn get_symlink(&self) -> Result<OsString> {
  - todo!()
  + // FIXME: assume that symlink can't be that long
  + let inode = self.disk_inode();
  + let data = self.data_block_mapping(0);
  + unsafe {
  + Ok(
  + bytes_to_os_str(std::slice::from_raw_parts(data, inode.i_size as usize))
  + .to_os_string(),
  + )
  + }
  }
  /// Get the child with the specified name.
  @@ -702,7 +710,8 @@ impl RafsInode for OndiskInodeWrapper {
  }
  fn get_symlink_size(&self) -> u16 {
  - todo!()
  + let inode = self.disk_inode();
  + inode.i_size as u16
  }
  fn collect_descendants_inodes(
  