io_uring for stream_copy_to_stream

Description

Hello,

It would be really nice to implement io_uring like here https://lwn.net/Articles/879724/ (talked in hn on https://news.ycombinator.com/item?id=30144652) to get stream_copy_to_stream() really performant.
example code here : https://lwn.net/ml/linux-kernel/af0d6b3e-85d0-9b61-4acd-5eef1375f934@gmail.com/
It would help a lot of stream proxy in php to be handled directly in the kernel, and increase drastically the performance.

From many test, stream_copy_to_stream() is sadly "slow" because it didn't use any trick, like sendfile() or 0copy, but instead is just a warper for a classic read/write loop, no gain in performance.

请求提到了 stream_copy_to_stream()，但没有指出源文件或测试。阅读链接的 io_uring 文章和示例，然后定位 stream_copy_to_stream() 的 C 实现及相关测试。完成时应包括已达成一致的实现方案，以及对所请求性能行为能够正常工作的验证。