[Report] requests are submitted to hardware in reverse order from nvme/virtio-blk queue_rqs()

[Ming Lei]

Hello,

Requests are added to plug list in reverse order, and both virtio-blk
and nvme retrieves request from plug list in order, so finally requests
are submitted to hardware in reverse order via nvme_queue_rqs() or
virtio_queue_rqs, see:

        io_uring       submit_bio  vdb      6302096     4096
        io_uring       submit_bio  vdb     12235072     4096
        io_uring       submit_bio  vdb      7682280     4096
        io_uring       submit_bio  vdb     11912464     4096
        io_uring virtio_queue_rqs  vdb     11912464     4096
        io_uring virtio_queue_rqs  vdb      7682280     4096
        io_uring virtio_queue_rqs  vdb     12235072     4096
        io_uring virtio_queue_rqs  vdb      6302096     4096


May this reorder be one problem for virtio-blk and nvme-pci?


Thanks,
Ming