[Qemu-devel] [PATCH 4/4] block/nbd-client: use non-blocking io channel for nbd negotiation

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

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
it's not a problem to send final NBD_CMD_DISC to non-blocking channel
but using sync qio interface, even not in coroutine.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/nbd-client.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/block/nbd-client.c b/block/nbd-client.c
index f0ad54ce21..79bc6b7e29 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -1029,7 +1029,7 @@ static int nbd_client_connect(BlockDriverState *bs,
 
     /* NBD handshake */
     logout("session init %s\n", export);
-    qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
+    qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL);
 
     client->info.request_sizes = true;
     client->info.structured_reply = true;
@@ -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 };
-- 
2.18.0