Re: [Qemu-devel] [PATCH v7 01/10] aio: Add "is_external" flag for event handlers

[Stefan Hajnoczi <stefanha@redhat.com>]

On Fri, Oct 23, 2015 at 11:08:05AM +0800, Fam Zheng wrote:
> All callers pass in false, and the real external ones will switch to
> true in coming patches.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Reviewed-by: Jeff Cody <jcody@redhat.com>
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  aio-posix.c                     |  6 ++++-
>  aio-win32.c                     |  5 ++++
>  async.c                         |  3 ++-
>  block/curl.c                    | 14 +++++-----
>  block/iscsi.c                   |  9 +++----
>  block/linux-aio.c               |  5 ++--
>  block/nbd-client.c              | 10 ++++---
>  block/nfs.c                     | 17 +++++-------
>  block/sheepdog.c                | 38 ++++++++++++++++++---------
>  block/ssh.c                     |  5 ++--
>  block/win32-aio.c               |  5 ++--
>  hw/block/dataplane/virtio-blk.c |  6 +++--
>  hw/scsi/virtio-scsi-dataplane.c | 24 +++++++++++------
>  include/block/aio.h             |  2 ++
>  iohandler.c                     |  3 ++-
>  nbd.c                           |  4 ++-
>  tests/test-aio.c                | 58 +++++++++++++++++++++++------------------
>  17 files changed, 130 insertions(+), 84 deletions(-)
> 
> diff --git a/aio-posix.c b/aio-posix.c
> index d477033..f0f9122 100644
> --- a/aio-posix.c
> +++ b/aio-posix.c
> @@ -25,6 +25,7 @@ struct AioHandler
>      IOHandler *io_write;
>      int deleted;
>      void *opaque;
> +    bool is_external;

Please explain why is_external is needed so this patch makes sense by
itself.

A doc comment explaining the semantics of this new flag would be best.
That way people modifying the code will know how to use it correctly.