Re: [Qemu-devel] [PATCH v6 05/20] block: Introduce byte-based aio read/write

[Kevin Wolf <kwolf@redhat.com>]

Am 05.05.2016 um 01:55 hat Eric Blake geschrieben:
> blk_aio_readv() and blk_aio_writev() are annoying in that they
> can't access sub-sector granularity, and cannot pass flags.
> Also, they require the caller to pass redundant information
> about the size of the I/O.
> 
> Add new blk_aio_preadv() and blk_aio_pwritev() functions to fix
> the flaws. The next few patches will upgrade callers, then
> finally delete the old interfaces.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  include/sysemu/block-backend.h |  6 ++++++
>  block/block-backend.c          | 16 ++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
> index 851376b..8d7839c 100644
> --- a/include/sysemu/block-backend.h
> +++ b/include/sysemu/block-backend.h
> @@ -110,9 +110,15 @@ int64_t blk_nb_sectors(BlockBackend *blk);
>  BlockAIOCB *blk_aio_readv(BlockBackend *blk, int64_t sector_num,
>                            QEMUIOVector *iov, int nb_sectors,
>                            BlockCompletionFunc *cb, void *opaque);
> +BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
> +                           QEMUIOVector *iov, BdrvRequestFlags flags,

If you have to respin for some reason, I think QEMUIOVectors are
commonly called qiov, whereas iov is usually the name for struct iovec.

Kevin