Re: [PATCH 1/6] block/io.c: fix bdrv_child_cb_drained_begin invocations from a coroutine

[Stefan Hajnoczi]

On Tue, Feb 08, 2022 at 10:36:50AM -0500, Emanuele Giuseppe Esposito wrote:
> Using bdrv_do_drained_begin_quiesce() in bdrv_child_cb_drained_begin()
> is not a good idea: the callback might be called when running
> a drain in a coroutine, and bdrv_drained_begin_poll() does not
> handle that case, resulting in assertion failure.
> 
> Instead, bdrv_do_drained_begin with no recursion and poll
> will accomplish the same thing (invoking bdrv_do_drained_begin_quiesce)
> but will firstly check if we are already in a coroutine, and exit
> from that via bdrv_co_yield_to_drain().
> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> ---
>  block.c                  | 2 +-
>  block/io.c               | 7 ++++++-
>  include/block/block-io.h | 8 +++++---
>  3 files changed, 12 insertions(+), 5 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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