Re: [Qemu-devel] [PATCH v3 01/17] block: stop relying on io_flush() in bdrv_drain_all()

[Stefan Hajnoczi]

On Mon, Jun 10, 2013 at 02:25:57PM +0200, Stefan Hajnoczi wrote:
> @@ -1427,26 +1456,18 @@ void bdrv_close_all(void)
>  void bdrv_drain_all(void)
>  {
>      BlockDriverState *bs;
> -    bool busy;
> -
> -    do {
> -        busy = qemu_aio_wait();
>  
> +    while (bdrv_requests_pending_all()) {
>          /* FIXME: We do not have timer support here, so this is effectively
>           * a busy wait.
>           */
>          QTAILQ_FOREACH(bs, &bdrv_states, list) {
>              if (!qemu_co_queue_empty(&bs->throttled_reqs)) {
>                  qemu_co_queue_restart_all(&bs->throttled_reqs);
> -                busy = true;
>              }
>          }
> -    } while (busy);
>  
> -    /* If requests are still pending there is a bug somewhere */
> -    QTAILQ_FOREACH(bs, &bdrv_states, list) {
> -        assert(QLIST_EMPTY(&bs->tracked_requests));
> -        assert(qemu_co_queue_empty(&bs->throttled_reqs));
> +        qemu_aio_wait();
>      }
>  }

tests/ide-test found an issue here: block.c invokes callbacks from a BH
so we may not yet have completed the request when this loop terminates.

Kevin: can you fold in this patch?

diff --git a/block.c b/block.c
index 31f7231..e176215 100644
--- a/block.c
+++ b/block.c
@@ -1469,6 +1469,9 @@ void bdrv_drain_all(void)
 
         qemu_aio_wait();
     }
+
+    /* Process pending completion BHs */
+    aio_poll(qemu_get_aio_context(), false);
 }
 
 /* make a BlockDriverState anonymous by removing from bdrv_state list.