+/*
+ * Check if we can regenerate the metadata for this session.
+ * Only kernel, UST per-uid and non-live sessions are supported.
+ *
+ * Return 0 if the metadata can be generated, a LTTNG_ERR code otherwise.
+ */
+static
+int check_metadata_regenerate_support(struct ltt_session *session)
+{
+ int ret;
+
+ assert(session);
+
+ if (session->live_timer != 0) {
+ ret = LTTNG_ERR_LIVE_SESSION;
+ goto end;
+ }
+ if (!session->active) {
+ ret = LTTNG_ERR_SESSION_NOT_STARTED;
+ goto end;
+ }
+ if (session->ust_session) {
+ switch (session->ust_session->buffer_type) {
+ case LTTNG_BUFFER_PER_UID:
+ break;
+ case LTTNG_BUFFER_PER_PID:
+ ret = LTTNG_ERR_PER_PID_SESSION;
+ goto end;
+ default:
+ assert(0);
+ ret = LTTNG_ERR_UNK;
+ goto end;
+ }
+ }
+ if (session->consumer->type == CONSUMER_DST_NET &&
+ session->consumer->relay_minor_version < 8) {
+ ret = LTTNG_ERR_RELAYD_VERSION_FAIL;
+ goto end;
+ }
+ ret = 0;
+
+end:
+ return ret;
+}
+
+static
+int ust_metadata_regenerate(struct ltt_ust_session *usess)
+{
+ int ret = 0;
+ struct buffer_reg_uid *uid_reg = NULL;
+ struct buffer_reg_session *session_reg = NULL;
+
+ rcu_read_lock();
+ cds_list_for_each_entry(uid_reg, &usess->buffer_reg_uid_list, lnode) {
+ struct ust_registry_session *registry;
+ struct ust_registry_channel *chan;
+ struct lttng_ht_iter iter_chan;
+
+ session_reg = uid_reg->registry;
+ registry = session_reg->reg.ust;
+
+ pthread_mutex_lock(®istry->lock);
+ registry->metadata_len_sent = 0;
+ memset(registry->metadata, 0, registry->metadata_alloc_len);
+ registry->metadata_len = 0;
+ registry->metadata_version++;
+ ret = ust_metadata_session_statedump(registry, NULL,
+ registry->major, registry->minor);
+ if (ret) {
+ pthread_mutex_unlock(®istry->lock);
+ ERR("Failed to generate session metadata (err = %d)",
+ ret);
+ goto end;
+ }
+ cds_lfht_for_each_entry(registry->channels->ht, &iter_chan.iter,
+ chan, node.node) {
+ struct ust_registry_event *event;
+ struct lttng_ht_iter iter_event;
+
+ ret = ust_metadata_channel_statedump(registry, chan);
+ if (ret) {
+ pthread_mutex_unlock(®istry->lock);
+ ERR("Failed to generate channel metadata "
+ "(err = %d)", ret);
+ goto end;
+ }
+ cds_lfht_for_each_entry(chan->ht->ht, &iter_event.iter,
+ event, node.node) {
+ ret = ust_metadata_event_statedump(registry,
+ chan, event);
+ if (ret) {
+ pthread_mutex_unlock(®istry->lock);
+ ERR("Failed to generate event metadata "
+ "(err = %d)", ret);
+ goto end;
+ }
+ }
+ }
+ pthread_mutex_unlock(®istry->lock);
+ }
+
+end:
+ rcu_read_unlock();
+ return ret;
+}
+
+/*
+ * Command LTTNG_METADATA_REGENERATE from the lttng-ctl library.
+ *
+ * Ask the consumer to truncate the existing metadata file(s) and
+ * then regenerate the metadata. Live and per-pid sessions are not
+ * supported and return an error.
+ *
+ * Return 0 on success or else a LTTNG_ERR code.
+ */
+int cmd_metadata_regenerate(struct ltt_session *session)
+{
+ int ret;
+
+ assert(session);
+
+ ret = check_metadata_regenerate_support(session);
+ if (ret) {
+ goto end;
+ }
+
+ if (session->kernel_session) {
+ ret = kernctl_session_metadata_regenerate(
+ session->kernel_session->fd);
+ if (ret < 0) {
+ ERR("Failed to regenerate the kernel metadata");
+ goto end;
+ }
+ }
+
+ if (session->ust_session) {
+ ret = ust_metadata_regenerate(session->ust_session);
+ if (ret < 0) {
+ ERR("Failed to regenerate the UST metadata");
+ goto end;
+ }
+ }
+ DBG("Cmd metadata regenerate for session %s", session->name);
+ ret = LTTNG_OK;
+
+end:
+ return ret;
+}
+
+