Enable keepalive option to track server availability.

Requested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/nbd-client.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/nbd-client.c b/block/nbd-client.c
index 790ecc1ee1..b57cea8482 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -1137,6 +1137,7 @@ static int nbd_client_connect(BlockDriverState *bs,
 
     /* NBD handshake */
     logout("session init %s\n", export);
+    qio_channel_set_keepalive(QIO_CHANNEL(sioc), true, NULL);
     qio_channel_set_blocking(QIO_CHANNEL(sioc), true, NULL);
 
     client->info.request_sizes = true;
-- 
2.18.0