Re: [Qemu-devel] [PATCH v1 1/3] block: block: introduce bdrv_io_plug() and bdrv_io_unplug()

[Paolo Bonzini]

Il 30/06/2014 17:47, Ming Lei ha scritto:
> From: Ming Lei <address@hidden>
>
> This patch introduces these two APIs so that following
> patches can support queuing I/O requests and submitting them
> at batch for improving I/O performance.
>
> Signed-off-by: Ming Lei <address@hidden>
> ---
>  block.c                   |   22 ++++++++++++++++++++++
>  include/block/block.h     |    3 +++
>  include/block/block_int.h |    4 ++++
>  3 files changed, 29 insertions(+)
>
> diff --git a/block.c b/block.c
> index 217f523..2b4ec5b 100644
> --- a/block.c
> +++ b/block.c
> @@ -1910,6 +1910,7 @@ void bdrv_drain_all(void)
>              bool bs_busy;
>
>              aio_context_acquire(aio_context);
> +            bdrv_io_unplug(bs);
>              bdrv_start_throttled_reqs(bs);
>              bs_busy = bdrv_requests_pending(bs);
>              bs_busy |= aio_poll(aio_context, bs_busy);
> @@ -5774,3 +5775,24 @@ bool bdrv_is_first_non_filter(BlockDriverState 
> *candidate)
>
>      return false;
>  }
> +
> +void bdrv_io_plug(BlockDriverState *bs)
> +{
> +    BlockDriver *drv = bs->drv;
> +    if (drv && drv->bdrv_io_plug) {
> +        drv->bdrv_io_plug(bs);
> +    } else if (bs->file) {
> +        bdrv_io_plug(bs->file);
> +    }
> +}
> +
> +int bdrv_io_unplug(BlockDriverState *bs)
> +{
> +    BlockDriver *drv = bs->drv;
> +    if (drv && drv->bdrv_io_unplug) {
> +        return drv->bdrv_io_unplug(bs);
> +    } else if (bs->file) {
> +        return bdrv_io_unplug(bs->file);
> +    }
> +    return 0;

I think this should return void (and that's how you use it in patch 3 
indeed).  If you fix this you can add my Reviewed-by tag.

Paolo

> +}
> diff --git a/include/block/block.h b/include/block/block.h
> index d0baf4f..ccced61 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -578,4 +578,7 @@ AioContext *bdrv_get_aio_context(BlockDriverState *bs);
>   */
>  void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context);
>
> +void bdrv_io_plug(BlockDriverState *bs);
> +int bdrv_io_unplug(BlockDriverState *bs);
> +
>  #endif
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 715c761..b5412fa 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -257,6 +257,10 @@ struct BlockDriver {
>      void (*bdrv_attach_aio_context)(BlockDriverState *bs,
>                                      AioContext *new_context);
>
> +    /* io queue for linux-aio */
> +    void (*bdrv_io_plug)(BlockDriverState *bs);
> +    int (*bdrv_io_unplug)(BlockDriverState *bs);
> +
>      QLIST_ENTRY(BlockDriver) list;
>  };