Re: [Qemu-devel] [PATCH 03/10] block: Add bdrv_co_readv/writev emulation

[Kevin Wolf <kwolf@redhat.com>]

Am 26.07.2011 13:49, schrieb Kevin Wolf:
> In order to be able to call bdrv_co_readv/writev for drivers that don't
> implement the functions natively, add an emulation that uses the AIO functions
> to implement them.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c      |   84 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  trace-events |    1 +
>  2 files changed, 77 insertions(+), 8 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 48413ae..2f589ac 100644
> --- a/block.c
> +++ b/block.c
> @@ -64,6 +64,12 @@ static BlockDriverAIOCB *bdrv_co_aio_readv_em(BlockDriverState *bs,
>  static BlockDriverAIOCB *bdrv_co_aio_writev_em(BlockDriverState *bs,
>          int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
>          BlockDriverCompletionFunc *cb, void *opaque);
> +static int coroutine_fn bdrv_co_readv_em(BlockDriverState *bs,
> +                                         int64_t sector_num, int nb_sectors,
> +                                         QEMUIOVector *iov);
> +static int coroutine_fn bdrv_co_writev_em(BlockDriverState *bs,
> +                                         int64_t sector_num, int nb_sectors,
> +                                         QEMUIOVector *iov);
>  
>  static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
>      QTAILQ_HEAD_INITIALIZER(bdrv_states);
> @@ -182,14 +188,19 @@ void bdrv_register(BlockDriver *bdrv)
>          bdrv->bdrv_aio_writev = bdrv_co_aio_writev_em;
>          bdrv->bdrv_read = bdrv_read_em;
>          bdrv->bdrv_write = bdrv_write_em;
> -     } else if (!bdrv->bdrv_aio_readv) {
> -        /* add AIO emulation layer */
> -        bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
> -        bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
> -    } else if (!bdrv->bdrv_read) {
> -        /* add synchronous IO emulation layer */
> -        bdrv->bdrv_read = bdrv_read_em;
> -        bdrv->bdrv_write = bdrv_write_em;
> +     } else {
> +        bdrv->bdrv_co_readv = bdrv_co_readv_em;
> +        bdrv->bdrv_co_writev = bdrv_co_writev_em;
> +
> +        if (!bdrv->bdrv_aio_readv) {
> +            /* add AIO emulation layer */
> +            bdrv->bdrv_aio_readv = bdrv_aio_readv_em;
> +            bdrv->bdrv_aio_writev = bdrv_aio_writev_em;
> +        } else if (!bdrv->bdrv_read) {
> +            /* add synchronous IO emulation layer */
> +            bdrv->bdrv_read = bdrv_read_em;
> +            bdrv->bdrv_write = bdrv_write_em;
> +        }
>      }
>  
>      if (!bdrv->bdrv_aio_flush)
> @@ -2868,6 +2879,63 @@ void qemu_aio_release(void *p)
>  }
>  
>  /**************************************************************/
> +/* Coroutine block device emulation */
> +
> +typedef struct CoroutineIOCompletion {
> +    Coroutine *coroutine;
> +    int ret;
> +} CoroutineIOCompletion;
> +
> +static void bdrv_co_io_em_complete(void *opaque, int ret)
> +{
> +    CoroutineIOCompletion *co = opaque;
> +
> +    co->ret = ret;
> +    qemu_coroutine_enter(co->coroutine, NULL);
> +}
> +
> +static int coroutine_fn bdrv_co_io_em(BlockDriverState *bs, int64_t sector_num,
> +                                      int nb_sectors, QEMUIOVector *iov,
> +                                      bool is_write)
> +{
> +    CoroutineIOCompletion co = {
> +        .coroutine = qemu_coroutine_self(),
> +        .ret = -EINPROGRESS,

This line doesn't compile with mingw32. Additionally, we never use this
value, so I just dropped it from the patch in the block queue.

Unless someone insists on it, I won't resend the series for this one-liner.

Kevin