diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/nbd-client.c | 22 | ||||
| -rw-r--r-- | block/nbd-client.h | 1 |
2 files changed, 23 insertions, 0 deletions
diff --git a/block/nbd-client.c b/block/nbd-client.c index f0ad54ce21..5ce4aa9520 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -76,8 +76,24 @@ static coroutine_fn void nbd_connection_entry(void *opaque) Error *local_err = NULL; while (!s->quit) { + /* + * The NBD client can only really be considered idle when it has + * yielded from qio_channel_readv_all_eof(), waiting for data. This is + * the point where the additional scheduled coroutine entry happens + * after nbd_client_attach_aio_context(). + * + * Therefore we keep an additional in_flight reference all the time and + * only drop it temporarily here. + * + * FIXME This is not safe because the QIOChannel could wake up the + * coroutine for a second time; it is not prepared for coroutine + * resumption from external code. + */ + bdrv_dec_in_flight(s->bs); assert(s->reply.handle == 0); ret = nbd_receive_reply(s->ioc, &s->reply, &local_err); + bdrv_inc_in_flight(s->bs); + if (local_err) { trace_nbd_read_reply_entry_fail(ret, error_get_pretty(local_err)); error_free(local_err); @@ -116,6 +132,8 @@ static coroutine_fn void nbd_connection_entry(void *opaque) s->quit = true; nbd_recv_coroutines_wake_all(s); + bdrv_dec_in_flight(s->bs); + s->connection_co = NULL; aio_wait_kick(); } @@ -970,6 +988,8 @@ void nbd_client_attach_aio_context(BlockDriverState *bs, { NBDClientSession *client = nbd_get_client_session(bs); qio_channel_attach_aio_context(QIO_CHANNEL(client->ioc), new_context); + + /* FIXME Really need a bdrv_inc_in_flight() here */ aio_co_schedule(new_context, client->connection_co); } @@ -1076,6 +1096,7 @@ static int nbd_client_connect(BlockDriverState *bs, * kick the reply mechanism. */ qio_channel_set_blocking(QIO_CHANNEL(sioc), false, NULL); client->connection_co = qemu_coroutine_create(nbd_connection_entry, client); + bdrv_inc_in_flight(bs); nbd_client_attach_aio_context(bs, bdrv_get_aio_context(bs)); logout("Established connection with NBD server\n"); @@ -1108,6 +1129,7 @@ int nbd_client_init(BlockDriverState *bs, { NBDClientSession *client = nbd_get_client_session(bs); + client->bs = bs; qemu_co_mutex_init(&client->send_mutex); qemu_co_queue_init(&client->free_sema); diff --git a/block/nbd-client.h b/block/nbd-client.h index d990207a5c..09e03013d2 100644 --- a/block/nbd-client.h +++ b/block/nbd-client.h @@ -35,6 +35,7 @@ typedef struct NBDClientSession { NBDClientRequest requests[MAX_NBD_REQUESTS]; NBDReply reply; + BlockDriverState *bs; bool quit; } NBDClientSession; |