Method writev

fs/cache/cached_fs.cpp:268–274

    }

    ssize_t writev(const struct iovec *iov, int iovcnt) override {
        auto ret = pwritev(iov, iovcnt, writeOffset_);
        if (ret > 0) {
            writeOffset_ += ret;
        }
        return ret;
    }

    int query(off_t offset, size_t count) override {
        auto ret = cache_store_->queryRefillRange(offset, count);