Method fsync

fs/extfs/extfs.cpp:1192–1203

        DO_EXT2FS(do_ext2fs_file_close(file))
    }
    virtual int fsync() override {
        if ((flags & (O_WRONLY | O_RDWR)) == 0) {
            errno = EBADF;
            return -1;
        }
        errcode_t ret = ext2fs_file_flush(file);
        if (ret) {
            errno = -parse_extfs_error(fs, ino, ret);
            return -1;
        }
        return flush_buffer();
    }
    virtual int fdatasync() override {
        return this->fsync();
    }