[PATCH v6 0/2] virtio-blk: support polling I/O and mq_ops->queue_rqs()

Suwan Kim
2022-04-06T17:28:34Z

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

Changes

v5 -> v6
- patch1 : virtblk_poll
- Remove memset in init_vq()
- Fix space indent in init_vq()
- Replace if condition with positive check in virtblk_map_queues()
if (i == HCTX_TYPE_POLL)
blk_mq_map_queues(&set->map[i]);
else
blk_mq_virtio_map_queues(&set->map[i], vblk->vdev, 0);
- Add Reviewed-by tags

- patch2 : virtio_queue_rqs
- Add Reviewed-by tags

v4 -> v5
- patch1 : virtblk_poll
- Replace "req_done" with "found" in virtblk_poll()
- Split for loop into two distinct for loop in init_vq()
that sets callback function for each default/poll queues
- Replace "if (i == HCTX_TYPE_DEFAULT)" with "i != HCTX_TYPE_POLL"
in virtblk_map_queues()
- Replace "virtblk_unmap_data(req, vbr);" with
"virtblk_unmap_data(req, blk_mq_rq_to_pdu(req);"
in virtblk_complete_batch()

- patch2 : virtio_queue_rqs
- Instead of using vbr.sg_num field, use vbr->sg_table.nents.
So, remove sg_num field in struct virtblk_req
- Drop the unnecessary argument of virtblk_add_req() because it
doens't need "data_sg" and "have_data". It can be derived from "vbr"
argument.
- Add Reviewed-by tag from Stefan

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 | 220 +++++++++++++++++++++++++++++++++----
1 file changed, 201 insertions(+), 19 deletions(-)

--
2.26.3