Re: [Qemu-devel] [PATCH v2 11/12] qed: Implement .bdrv_drain

[Kevin Wolf <kwolf@redhat.com>]

Am 12.10.2015 um 13:50 hat Fam Zheng geschrieben:
> The "need_check_timer" is used to clear the "NEED_CHECK" flag in the
> image header after a grace period once metadata update has finished. In
> compliance to the bdrv_drain semantics we should make sure it remains
> deleted once .bdrv_drain is called.
> 
> Call the qed_need_check_timer_cb manually to update the header
> immediately.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>

What happens if a new allocating write request is issued during the
drained section and the timer gets reenabled?

Kevin

>  block/qed.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/block/qed.c b/block/qed.c
> index a7ff1d9..23bd273 100644
> --- a/block/qed.c
> +++ b/block/qed.c
> @@ -381,6 +381,12 @@ static void bdrv_qed_attach_aio_context(BlockDriverState *bs,
>      }
>  }
>  
> +static void bdrv_qed_drain(BlockDriverState *bs)
> +{
> +    qed_cancel_need_check_timer(bs->opaque);
> +    qed_need_check_timer_cb(bs->opaque);
> +}
> +
>  static int bdrv_qed_open(BlockDriverState *bs, QDict *options, int flags,
>                           Error **errp)
>  {
> @@ -1683,6 +1689,7 @@ static BlockDriver bdrv_qed = {
>      .bdrv_check               = bdrv_qed_check,
>      .bdrv_detach_aio_context  = bdrv_qed_detach_aio_context,
>      .bdrv_attach_aio_context  = bdrv_qed_attach_aio_context,
> +    .bdrv_drain               = bdrv_qed_drain,
>  };
>  
>  static void bdrv_qed_init(void)
> -- 
> 2.6.1
>