19.02.2019 16:18, Vladimir Sementsov-Ogievskiy wrote:
> 12.02.2019 1:02, Eric Blake wrote:
>> On 2/11/19 6:56 AM, Vladimir Sementsov-Ogievskiy wrote:
>>> Now negotiation is done in coroutine, so to take benefit of it let's
>>> use non-blocking model.
>>>
>>> Note that QIOChannel handle synchronous io calls correctly anyway, so
>>
>> s/handle/handles/
>>
>>> it's not a problem to send final NBD_CMD_DISC to non-blocking channel
>>> but using sync qio interface, even not in coroutine.
>>
>> s/not in/when not in a/
>>
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
>>> ---
>>> block/nbd-client.c | 10 +++-------
>>> 1 file changed, 3 insertions(+), 7 deletions(-)
>>
>> This fixes qemu as NBD client for use in block devices, but what about
>> qemu as NBD client in qemu-nbd? Does that need any updates? Then
>> again, your observation about QIO doing the right thing for both
>> blocking (qemu-nbd) and non-blocking (block layer) channels seems to
>> cover that.
>
> In qemu-nbd client works in a separate thread, so, I think, we don't need
> nonblocking: we have a thread anyway.
>
> On the other hand, is my code in nbd_receive_common safe, keeping in mind
> that we call it from separate thread?
>
> Are qio_channel_attach_aio_context, qemu_aio_coroutine_enter, AIO_WAIT_WHILE
> thread-safe?
Could somebody shed a bit of light here, please?
>
>>
>>> @@ -1072,9 +1072,6 @@ static int nbd_client_connect(BlockDriverState *bs,
>>> object_ref(OBJECT(client->ioc));
>>> }
>>> - /* Now that we're connected, set the socket to be non-blocking and
>>> - * kick the reply mechanism. */
>>> - qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
>>> client->connection_co = qemu_coroutine_create(nbd_connection_entry,
>>> client);
>>> nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs));
>>> @@ -1083,9 +1080,8 @@ static int nbd_client_connect(BlockDriverState *bs,
>>> fail:
>>> /*
>>> - * We have connected, but must fail for other reasons. The
>>> - * connection is still blocking; send NBD_CMD_DISC as a courtesy
>>> - * to the server.
>>> + * We have connected, but must fail for other reasons.
>>> + * Send NBD_CMD_DISC as a courtesy to the server.
>>> */
>>> {
>>> NBDRequest request = { .type = NBD_CMD_DISC };
>>>
>>
>
>
--
Best regards,
Vladimir
