static void nbd_teardown_connection(NbdClientSession *client)
{
struct nbd_request request = {
.type = NBD_CMD_DISC,
.from = 0,
.len = 0
};
nbd_send_request(client->sock, &request);
/* finish any pending coroutines */
shutdown(client->sock, 2);
nbd_recv_coroutines_enter_all(client);
qemu_aio_set_fd_handler(client->sock, NULL, NULL, NULL);
closesocket(client->sock);
client->sock = -1;
}
void nbd_client_session_close(NbdClientSession *client)
{
if (!client->bs) {
return;
}
nbd_teardown_connection(client);
client->bs = NULL;
}
int nbd_client_session_init(NbdClientSession *client, BlockDriverState *bs,
int sock, const char *export)
{
int ret;
/* NBD handshake */
logout("session init %s\n", export);
qemu_set_block(sock);
ret = nbd_receive_negotiate(sock, export,
&client->nbdflags, &client->size,
&client->blocksize);
if (ret < 0) {
logout("Failed to negotiate with the NBD server\n");
closesocket(sock);
return ret;
}
qemu_co_mutex_init(&client->send_mutex);
qemu_co_mutex_init(&client->free_sema);
client->bs = bs;
client->sock = sock;
/* Now that we're connected, set the socket to be non-blocking and
* kick the reply mechanism. */
qemu_set_nonblock(sock);
qemu_aio_set_fd_handler(sock, nbd_reply_ready, NULL, client);
logout("Established connection with NBD server\n");
return 0;
}
static void nbd_teardown_connection(BlockDriverState *bs)
{
NbdClientSession *client = nbd_get_client_session(bs);
/* finish any pending coroutines */
shutdown(client->sock, 2);
nbd_recv_coroutines_enter_all(client);
nbd_client_detach_aio_context(bs);
closesocket(client->sock);
client->sock = -1;
}
static coroutine_fn void nbd_read_reply_entry(void *opaque)
{
NBDClientSession *s = opaque;
uint64_t i;
int ret;
Error *local_err = NULL;
for (;;) {
assert(s->reply.handle == 0);
ret = nbd_receive_reply(s->ioc, &s->reply, &local_err);
if (ret < 0) {
error_report_err(local_err);
}
if (ret <= 0) {
break;
}
/* There's no need for a mutex on the receive side, because the
* handler acts as a synchronization point and ensures that only
* one coroutine is called until the reply finishes.
*/
i = HANDLE_TO_INDEX(s, s->reply.handle);
if (i >= MAX_NBD_REQUESTS || !s->recv_coroutine[i]) {
break;
}
/* We're woken up by the recv_coroutine itself. Note that there
* is no race between yielding and reentering read_reply_co. This
* is because:
*
* - if recv_coroutine[i] runs on the same AioContext, it is only
* entered after we yield
*
* - if recv_coroutine[i] runs on a different AioContext, reentering
* read_reply_co happens through a bottom half, which can only
* run after we yield.
*/
aio_co_wake(s->recv_coroutine[i]);
qemu_coroutine_yield();
}
nbd_recv_coroutines_enter_all(s);
s->read_reply_co = NULL;
}
static void nbd_teardown_connection(BlockDriverState *bs)
{
NbdClientSession *client = nbd_get_client_session(bs);
if (!client->ioc) { /* Already closed */
return;
}
/* finish any pending coroutines */
qio_channel_shutdown(client->ioc,
QIO_CHANNEL_SHUTDOWN_BOTH,
NULL);
nbd_recv_coroutines_enter_all(client);
nbd_client_detach_aio_context(bs);
object_unref(OBJECT(client->sioc));
client->sioc = NULL;
object_unref(OBJECT(client->ioc));
client->ioc = NULL;
}
static void nbd_reply_ready(void *opaque)
{
NbdClientSession *s = opaque;
uint64_t i;
int ret;
if (s->reply.handle == 0) {
/* No reply already in flight. Fetch a header. It is possible
* that another thread has done the same thing in parallel, so
* the socket is not readable anymore.
*/
ret = nbd_receive_reply(s->sock, &s->reply);
if (ret == -EAGAIN) {
return;
}
if (ret < 0) {
s->reply.handle = 0;
goto fail;
}
}
/* There's no need for a mutex on the receive side, because the
* handler acts as a synchronization point and ensures that only
* one coroutine is called until the reply finishes. */
i = HANDLE_TO_INDEX(s, s->reply.handle);
if (i >= MAX_NBD_REQUESTS) {
goto fail;
}
if (s->recv_coroutine[i]) {
qemu_coroutine_enter(s->recv_coroutine[i], NULL);
return;
}
fail:
nbd_recv_coroutines_enter_all(s);
}
