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authorVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>2021-06-10 13:07:50 +0300
committerEric Blake <eblake@redhat.com>2021-06-18 10:59:53 -0500
commite0e67cbe58f42500e3451c46b3caba572f2a965f (patch)
treeadc32dfa370ad235d0318fad2571c8bc6829aa55 /nbd
parent130d49baa50655729f09efb72e77bebf09421dd7 (diff)
nbd/client-connection: implement connection retry
Add an option for a thread to retry connecting until it succeeds. We'll use nbd/client-connection both for reconnect and for initial connection in nbd_open(), so we need a possibility to use same NBDClientConnection instance to connect once in nbd_open() and then use retry semantics for reconnect. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20210610100802.5888-21-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> [eblake: grammar tweak] Signed-off-by: Eric Blake <eblake@redhat.com>
Diffstat (limited to 'nbd')
-rw-r--r--nbd/client-connection.c56
1 files changed, 43 insertions, 13 deletions
diff --git a/nbd/client-connection.c b/nbd/client-connection.c
index 4ed37cd73f..032b38ed3e 100644
--- a/nbd/client-connection.c
+++ b/nbd/client-connection.c
@@ -35,6 +35,7 @@ struct NBDClientConnection {
QCryptoTLSCreds *tlscreds;
NBDExportInfo initial_info;
bool do_negotiation;
+ bool do_retry;
QemuMutex mutex;
@@ -61,6 +62,15 @@ struct NBDClientConnection {
Coroutine *wait_co;
};
+/*
+ * The function isn't protected by any mutex, only call it when the client
+ * connection attempt has not yet started.
+ */
+void nbd_client_connection_enable_retry(NBDClientConnection *conn)
+{
+ conn->do_retry = true;
+}
+
NBDClientConnection *nbd_client_connection_new(const SocketAddress *saddr,
bool do_negotiation,
const char *export_name,
@@ -155,23 +165,43 @@ static void *connect_thread_func(void *opaque)
NBDClientConnection *conn = opaque;
int ret;
bool do_free;
+ uint64_t timeout = 1;
+ uint64_t max_timeout = 16;
- conn->sioc = qio_channel_socket_new();
+ while (true) {
+ conn->sioc = qio_channel_socket_new();
- error_free(conn->err);
- conn->err = NULL;
- conn->updated_info = conn->initial_info;
+ error_free(conn->err);
+ conn->err = NULL;
+ conn->updated_info = conn->initial_info;
- ret = nbd_connect(conn->sioc, conn->saddr,
- conn->do_negotiation ? &conn->updated_info : NULL,
- conn->tlscreds, &conn->ioc, &conn->err);
- if (ret < 0) {
- object_unref(OBJECT(conn->sioc));
- conn->sioc = NULL;
- }
+ ret = nbd_connect(conn->sioc, conn->saddr,
+ conn->do_negotiation ? &conn->updated_info : NULL,
+ conn->tlscreds, &conn->ioc, &conn->err);
+
+ /*
+ * conn->updated_info will finally be returned to the user. Clear the
+ * pointers to our internally allocated strings, which are IN parameters
+ * of nbd_receive_negotiate() and therefore nbd_connect(). Caller
+ * shoudn't be interested in these fields.
+ */
+ conn->updated_info.x_dirty_bitmap = NULL;
+ conn->updated_info.name = NULL;
+
+ if (ret < 0) {
+ object_unref(OBJECT(conn->sioc));
+ conn->sioc = NULL;
+ if (conn->do_retry) {
+ sleep(timeout);
+ if (timeout < max_timeout) {
+ timeout *= 2;
+ }
+ continue;
+ }
+ }
- conn->updated_info.x_dirty_bitmap = NULL;
- conn->updated_info.name = NULL;
+ break;
+ }
qemu_mutex_lock(&conn->mutex);