Implement reconnect. To achieve this:
1. Move from quit bool variable to state. 4 states are introduced:
connecting-wait: means, that reconnecting is in progress, and there
were small number of reconnect attempts, so all requests are
waiting for the connection.
connecting-nowait: reconnecting is in progress, there were a lot of
attempts of reconnect, all requests will return errors.
connected: normal state
quit: exiting after fatal error or on close
Possible transitions are:
* -> quit
connecting-* -> connected
connecting-wait -> connecting-nowait
connected -> connecting-wait
2. Implement reconnect in connection_co. So, in connecting-* mode,
connection_co, tries to reconnect every NBD_RECONNECT_NS.
Configuring of this parameter (as well as NBD_RECONNECT_ATTEMPTS,
which specifies bound of transition from connecting-wait to
connecting-nowait) may be done as a follow-up patch.
3. Retry nbd queries on channel error, if we are in connecting-wait
state.
4. In init, wait until for connection until transition to
connecting-nowait. So, NBD_RECONNECT_ATTEMPTS is a bound of fail
for initial connection too.
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
block/nbd-client.h | 2 +
block/nbd-client.c | 170 ++++++++++++++++++++++++++++++++++++++---------------
2 files changed, 123 insertions(+), 49 deletions(-)
diff --git a/block/nbd-client.h b/block/nbd-client.h
index 2561e1ea42..1249f2eb52 100644
--- a/block/nbd-client.h
+++ b/block/nbd-client.h
@@ -44,6 +44,8 @@ typedef struct NBDClientSession {
bool receiving;
int connect_status;
Error *connect_err;
+ int connect_attempts;
+ bool wait_in_flight;
NBDClientRequest requests[MAX_NBD_REQUESTS];
NBDReply reply;
diff --git a/block/nbd-client.c b/block/nbd-client.c
index f22ed7f404..49b1f67047 100644
--- a/block/nbd-client.c
+++ b/block/nbd-client.c
@@ -41,10 +41,16 @@ static int nbd_client_connect(BlockDriverState *bs,
const char *hostname,
Error **errp);
-/* @ret would be used for reconnect in future */
static void nbd_channel_error(NBDClientSession *s, int ret)
{
- s->state = NBD_CLIENT_QUIT;
+ if (ret == -EIO) {
+ if (s->state == NBD_CLIENT_CONNECTED) {
+ s->state = NBD_CLIENT_CONNECTING_WAIT;
+ s->connect_attempts = 0;
+ }
+ } else {
+ s->state = NBD_CLIENT_QUIT;
+ }
}
static void nbd_recv_coroutines_wake_all(NBDClientSession *s)
@@ -90,6 +96,19 @@ typedef struct NBDConnection {
uint64_t reconnect_timeout;
} NBDConnection;
+static bool nbd_client_connecting(NBDClientSession *client)
+{
+ return client->state == NBD_CLIENT_CONNECTING_WAIT ||
+ client->state == NBD_CLIENT_CONNECTING_NOWAIT ||
+ client->state == NBD_CLIENT_CONNECTING_INIT;
+}
+
+static bool nbd_client_connecting_wait(NBDClientSession *client)
+{
+ return client->state == NBD_CLIENT_CONNECTING_WAIT ||
+ client->state == NBD_CLIENT_CONNECTING_INIT;
+}
+
static coroutine_fn void nbd_connection_entry(void *opaque)
{
NBDConnection *con = opaque;
@@ -98,26 +117,55 @@ static coroutine_fn void nbd_connection_entry(void *opaque)
int ret = 0;
Error *local_err = NULL;
- if (con->reconnect_attempts != 0) {
- error_setg(&s->connect_err, "Reconnect is not supported yet");
- s->connect_status = -EINVAL;
- nbd_channel_error(s, s->connect_status);
- return;
- }
+ while (s->state != NBD_CLIENT_QUIT) {
+ assert(s->reply.handle == 0);
- s->connect_status = nbd_client_connect(con->bs, con->saddr,
- con->export, con->tlscreds,
- con->hostname, &s->connect_err);
- if (s->connect_status < 0) {
- nbd_channel_error(s, s->connect_status);
- return;
- }
+ if (nbd_client_connecting(s)) {
+ if (s->connect_attempts == con->reconnect_attempts) {
+ s->state = NBD_CLIENT_CONNECTING_NOWAIT;
+ qemu_co_queue_restart_all(&s->free_sema);
+ }
- /* successfully connected */
- s->state = NBD_CLIENT_CONNECTED;
+ qemu_co_mutex_lock(&s->send_mutex);
+
+ while (s->in_flight > 0) {
+ qemu_co_mutex_unlock(&s->send_mutex);
+ nbd_recv_coroutines_wake_all(s);
+ s->wait_in_flight = true;
+ qemu_coroutine_yield();
+ s->wait_in_flight = false;
+ qemu_co_mutex_lock(&s->send_mutex);
+ }
+
+ qemu_co_mutex_unlock(&s->send_mutex);
+
+ /* Now we are sure, that nobody accessing the channel now and
nobody
+ * will try to access the channel, until we set state to CONNECTED
+ */
+
+ s->connect_status = nbd_client_connect(con->bs, con->saddr,
+ con->export, con->tlscreds,
+ con->hostname, &local_err);
+ s->connect_attempts++;
+ error_free(s->connect_err);
+ s->connect_err = NULL;
+ error_propagate(&s->connect_err, local_err);
+ local_err = NULL;
+ if (s->connect_status == -EINVAL) {
+ /* Protocol error or something like this */
+ nbd_channel_error(s, s->connect_status);
+ continue;
+ }
+ if (s->connect_status < 0) {
+ qemu_co_sleep_ns(QEMU_CLOCK_REALTIME, con->reconnect_timeout);
+ continue;
+ }
+
+ /* successfully connected */
+ s->state = NBD_CLIENT_CONNECTED;
+ qemu_co_queue_restart_all(&s->free_sema);
+ }
- while (s->state != NBD_CLIENT_QUIT) {
- assert(s->reply.handle == 0);
s->receiving = true;
ret = nbd_receive_reply(s->ioc, &s->reply, &local_err);
s->receiving = false;
@@ -158,6 +206,7 @@ stat