On Fri, Feb 05, 2021 at 06:13:09PM +0800, Jiahui Cen wrote:
> Add retry_request_cb in BlockDevOps to do device specific retry action.
> Backend's timer would be registered only when the backend is set 'retry'
> on errors and the device supports retry action.
> 
> Signed-off-by: Jiahui Cen <cenjiahui@huawei.com>
> Signed-off-by: Ying Fang <fangying1@huawei.com>
> ---
>  block/block-backend.c          | 8 ++++++++
>  include/sysemu/block-backend.h | 4 ++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/block/block-backend.c b/block/block-backend.c
> index 3a9d55cbe3..a8bfaf6e4a 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -995,6 +995,14 @@ void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
>      blk->dev_ops = ops;
>      blk->dev_opaque = opaque;
>  
> +    if ((blk->on_read_error == BLOCKDEV_ON_ERROR_RETRY ||
> +         blk->on_write_error == BLOCKDEV_ON_ERROR_RETRY) &&
> +        ops->retry_request_cb) {
> +        blk->retry_timer = aio_timer_new(blk->ctx, QEMU_CLOCK_REALTIME,
> +                                         SCALE_MS, ops->retry_request_cb,
> +                                         opaque);
> +    }

I didn't see anything that handles AioContext changes. If the
BlockBackend is detached from the current AioContext and attached to a
different one, then it is necessary to delete the old timer and create
a new one.

Stefan