Re: [PATCH v5 12/21] xen-block: implement BlockDevOps->drained_begin()

[Anthony PERARD]

On Thu, May 04, 2023 at 03:53:18PM -0400, Stefan Hajnoczi wrote:
> Detach event channels during drained sections to stop I/O submission
> from the ring. xen-block is no longer reliant on aio_disable_external()
> after this patch. This will allow us to remove the
> aio_disable_external() API once all other code that relies on it is
> converted.
> 
> Extend xen_device_set_event_channel_context() to allow ctx=NULL. The
> event channel still exists but the event loop does not monitor the file
> descriptor. Event channel processing can resume by calling
> xen_device_set_event_channel_context() with a non-NULL ctx.
> 
> Factor out xen_device_set_event_channel_context() calls in
> hw/block/dataplane/xen-block.c into attach/detach helper functions.
> Incidentally, these don't require the AioContext lock because
> aio_set_fd_handler() is thread-safe.
> 
> It's safer to register BlockDevOps after the dataplane instance has been
> created. The BlockDevOps .drained_begin/end() callbacks depend on the
> dataplane instance, so move the blk_set_dev_ops() call after
> xen_block_dataplane_create().
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>

Thanks,

-- 
Anthony PERARD