Method pwrite

fs/xfile.cpp:63–66

            return pio("pread", _and_pread(), buf, count, offset);
        }
        virtual ssize_t pwrite(const void *buf, size_t count, off_t offset) override
        {
            return pio("pwrite", _and_pwrite(), (void*)buf, count, offset);
        }
        virtual int fsync() override
        {
            for (auto x: m_files)