[PATCH v4 0/2] virtio-blk: support polling I/O and mq_ops->queue_rqs()

[Suwan Kim <suwan.kim027@gmail.com>]

This patch serise adds support for polling I/O and mq_ops->queue_rqs()
to virtio-blk driver.

Changes

v3 -> v4
    - patch1 : virtblk_poll
        - Add print the number of default/read/poll queues in init_vq()
        - Add blk_mq_start_stopped_hw_queues() to virtblk_poll()
              virtblk_poll()
                  ...
                  if (req_done)
		                   blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
                  ...

    - patch2 : virtio_queue_rqs
        - Modify virtio_queue_rqs() to hold lock only once when it adds
          requests to virtqueue just before virtqueue notify.
	  It will guarantee that virtio_queue_rqs() will not use
	  previous req again.

v2 -> v3
        - Fix warning by kernel test robot
          
            static int virtblk_poll()
                ...
                if (!blk_mq_add_to_batch(req, iob, virtblk_result(vbr),
                                                   -> vbr->status,

v1 -> v2
        - To receive the number of poll queues from user,
          use module parameter instead of QEMU uapi change.

        - Add the comment about virtblk_map_queues().

        - Add support for mq_ops->queue_rqs() to implement submit side
          batch.

Suwan Kim (2):
  virtio-blk: support polling I/O
  virtio-blk: support mq_ops->queue_rqs()

 drivers/block/virtio_blk.c | 222 ++++++++++++++++++++++++++++++++++---
 1 file changed, 207 insertions(+), 15 deletions(-)

-- 
2.26.3