Fix: acquire stream lock during kernel metadata snapshot
[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c
index e5c0c2e83a3930e1079ef96d056767b64893a7c7..3455f827b6b715c5415bcb3ee11c0d6147a46972 100644 (file)
@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License, version 2 only,
@@ -47,7 +48,6 @@
 
 extern struct lttng_consumer_global_data consumer_data;
 extern int consumer_poll_timeout;
-extern volatile int consumer_quit;
 
 /*
  * Take a snapshot for a specific fd
@@ -60,14 +60,30 @@ int lttng_kconsumer_take_snapshot(struct lttng_consumer_stream *stream)
        int infd = stream->wait_fd;
 
        ret = kernctl_snapshot(infd);
-       if (ret != 0) {
+       /*
+        * -EAGAIN is not an error, it just means that there is no data to
+        *  be read.
+        */
+       if (ret != 0 && ret != -EAGAIN) {
                PERROR("Getting sub-buffer snapshot.");
-               ret = -errno;
        }
 
        return ret;
 }
 
+/*
+ * Sample consumed and produced positions for a specific fd.
+ *
+ * Returns 0 on success, < 0 on error.
+ */
+int lttng_kconsumer_sample_snapshot_positions(
+               struct lttng_consumer_stream *stream)
+{
+       assert(stream);
+
+       return kernctl_snapshot_sample_positions(stream->wait_fd);
+}
+
 /*
  * Get the produced position
  *
@@ -82,7 +98,6 @@ int lttng_kconsumer_get_produced_snapshot(struct lttng_consumer_stream *stream,
        ret = kernctl_snapshot_get_produced(infd, pos);
        if (ret != 0) {
                PERROR("kernctl_snapshot_get_produced");
-               ret = -errno;
        }
 
        return ret;
@@ -102,7 +117,6 @@ int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
        ret = kernctl_snapshot_get_consumed(infd, pos);
        if (ret != 0) {
                PERROR("kernctl_snapshot_get_consumed");
-               ret = -errno;
        }
 
        return ret;
@@ -118,7 +132,6 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                struct lttng_consumer_local_data *ctx)
 {
        int ret;
-       unsigned long consumed_pos, produced_pos;
        struct lttng_consumer_channel *channel;
        struct lttng_consumer_stream *stream;
 
@@ -141,8 +154,7 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
        }
 
        cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
-               /* Are we at a position _before_ the first available packet ? */
-               bool before_first_packet = true;
+               unsigned long consumed_pos, produced_pos;
 
                health_code_update();
 
@@ -179,18 +191,21 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                        DBG("Kernel consumer snapshot stream %s/%s (%" PRIu64 ")",
                                        path, stream->name, stream->key);
                }
-               if (relayd_id != -1ULL) {
-                       ret = consumer_send_relayd_streams_sent(relayd_id);
+
+               ret = kernctl_buffer_flush_empty(stream->wait_fd);
+               if (ret < 0) {
+                       /*
+                        * Doing a buffer flush which does not take into
+                        * account empty packets. This is not perfect
+                        * for stream intersection, but required as a
+                        * fall-back when "flush_empty" is not
+                        * implemented by lttng-modules.
+                        */
+                       ret = kernctl_buffer_flush(stream->wait_fd);
                        if (ret < 0) {
-                               ERR("sending streams sent to relayd");
+                               ERR("Failed to flush kernel stream");
                                goto end_unlock;
                        }
-               }
-
-               ret = kernctl_buffer_flush(stream->wait_fd);
-               if (ret < 0) {
-                       ERR("Failed to flush kernel stream");
-                       ret = -errno;
                        goto end_unlock;
                }
 
@@ -217,7 +232,6 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                                        &stream->max_sb_size);
                        if (ret < 0) {
                                ERR("Getting kernel max_sb_size");
-                               ret = -errno;
                                goto end_unlock;
                        }
                }
@@ -229,7 +243,6 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                while (consumed_pos < produced_pos) {
                        ssize_t read_len;
                        unsigned long len, padded_len;
-                       int lost_packet = 0;
 
                        health_code_update();
 
@@ -237,36 +250,25 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 
                        ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
                        if (ret < 0) {
-                               if (errno != EAGAIN) {
+                               if (ret != -EAGAIN) {
                                        PERROR("kernctl_get_subbuf snapshot");
-                                       ret = -errno;
                                        goto end_unlock;
                                }
                                DBG("Kernel consumer get subbuf failed. Skipping it.");
                                consumed_pos += stream->max_sb_size;
-
-                               /*
-                                * Start accounting lost packets only when we
-                                * already have extracted packets (to match the
-                                * content of the final snapshot).
-                                */
-                               if (!before_first_packet) {
-                                       lost_packet = 1;
-                               }
+                               stream->chan->lost_packets++;
                                continue;
                        }
 
                        ret = kernctl_get_subbuf_size(stream->wait_fd, &len);
                        if (ret < 0) {
                                ERR("Snapshot kernctl_get_subbuf_size");
-                               ret = -errno;
                                goto error_put_subbuf;
                        }
 
                        ret = kernctl_get_padded_subbuf_size(stream->wait_fd, &padded_len);
                        if (ret < 0) {
                                ERR("Snapshot kernctl_get_padded_subbuf_size");
-                               ret = -errno;
                                goto error_put_subbuf;
                        }
 
@@ -292,20 +294,9 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                        ret = kernctl_put_subbuf(stream->wait_fd);
                        if (ret < 0) {
                                ERR("Snapshot kernctl_put_subbuf");
-                               ret = -errno;
                                goto end_unlock;
                        }
                        consumed_pos += stream->max_sb_size;
-
-                       /*
-                        * Only account lost packets located between
-                        * succesfully extracted packets (do not account before
-                        * and after since they are not visible in the
-                        * resulting snapshot).
-                        */
-                       stream->chan->lost_packets += lost_packet;
-                       lost_packet = 0;
-                       before_first_packet = false;
                }
 
                if (relayd_id == (uint64_t) -1ULL) {
@@ -331,7 +322,6 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
 error_put_subbuf:
        ret = kernctl_put_subbuf(stream->wait_fd);
        if (ret < 0) {
-               ret = -errno;
                ERR("Snapshot kernctl_put_subbuf error path");
        }
 end_unlock:
@@ -346,7 +336,7 @@ end:
  *
  * Returns 0 on success, < 0 on error
  */
-int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
+static int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
                uint64_t relayd_id, struct lttng_consumer_local_data *ctx)
 {
        int ret, use_relayd = 0;
@@ -365,11 +355,12 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        if (!metadata_channel) {
                ERR("Kernel snapshot metadata not found for key %" PRIu64, key);
                ret = -1;
-               goto error;
+               goto error_no_channel;
        }
 
        metadata_stream = metadata_channel->metadata_stream;
        assert(metadata_stream);
+       pthread_mutex_lock(&metadata_stream->lock);
 
        /* Flag once that we have a valid relayd for the stream. */
        if (relayd_id != (uint64_t) -1ULL) {
@@ -379,7 +370,7 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        if (use_relayd) {
                ret = consumer_send_relayd_stream(metadata_stream, path);
                if (ret < 0) {
-                       goto error;
+                       goto error_snapshot;
                }
        } else {
                ret = utils_create_stream_file(path, metadata_stream->name,
@@ -387,7 +378,7 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
                                metadata_stream->tracefile_count_current,
                                metadata_stream->uid, metadata_stream->gid, NULL);
                if (ret < 0) {
-                       goto error;
+                       goto error_snapshot;
                }
                metadata_stream->out_fd = ret;
        }
@@ -395,12 +386,13 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        do {
                health_code_update();
 
-               ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx);
+               ret_read = lttng_kconsumer_read_subbuffer(metadata_stream, ctx, NULL);
                if (ret_read < 0) {
                        if (ret_read != -EAGAIN) {
                                ERR("Kernel snapshot reading metadata subbuffer (ret: %zd)",
                                                ret_read);
-                               goto error;
+                               ret = ret_read;
+                               goto error_snapshot;
                        }
                        /* ret_read is negative at this point so we will exit the loop. */
                        continue;
@@ -425,11 +417,12 @@ int lttng_kconsumer_snapshot_metadata(uint64_t key, char *path,
        }
 
        ret = 0;
-
+error_snapshot:
+       pthread_mutex_unlock(&metadata_stream->lock);
        cds_list_del(&metadata_stream->send_node);
        consumer_stream_destroy(metadata_stream, NULL);
        metadata_channel->metadata_stream = NULL;
-error:
+error_no_channel:
        rcu_read_unlock();
        return ret;
 }
@@ -471,10 +464,10 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
        {
                /* Session daemon status message are handled in the following call. */
-               ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
+               consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
                                msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
                                &msg.u.relayd_sock.sock, msg.u.relayd_sock.session_id,
-                                msg.u.relayd_sock.relayd_session_id);
+                               msg.u.relayd_sock.relayd_session_id);
                goto end_nosignal;
        }
        case LTTNG_CONSUMER_ADD_CHANNEL:
@@ -543,9 +536,20 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                } else {
                        ret = consumer_add_channel(new_channel, ctx);
                }
-               if (CONSUMER_CHANNEL_TYPE_DATA) {
+               if (msg.u.channel.type == CONSUMER_CHANNEL_TYPE_DATA && !ret) {
+                       int monitor_start_ret;
+
+                       DBG("Consumer starting monitor timer");
                        consumer_timer_live_start(new_channel,
                                        msg.u.channel.live_timer_interval);
+                       monitor_start_ret = consumer_timer_monitor_start(
+                                       new_channel,
+                                       msg.u.channel.monitor_timer_interval);
+                       if (monitor_start_ret < 0) {
+                               ERR("Starting channel monitoring timer failed");
+                               goto end_nosignal;
+                       }
+
                }
 
                health_code_update();
@@ -643,7 +647,8 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                msg.u.stream.cpu,
                                &alloc_ret,
                                channel->type,
-                               channel->monitor);
+                               channel->monitor,
+                               msg.u.stream.trace_archive_id);
                if (new_stream == NULL) {
                        switch (alloc_ret) {
                        case -ENOMEM:
@@ -657,6 +662,8 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
 
                new_stream->chan = channel;
                new_stream->wait_fd = fd;
+               consumer_stream_update_channel_attributes(new_stream,
+                               channel);
                switch (channel->output) {
                case CONSUMER_CHANNEL_SPLICE:
                        new_stream->output = LTTNG_EVENT_SPLICE;
@@ -726,30 +733,31 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                                consumer_stream_free(new_stream);
                                goto end_nosignal;
                        }
+
+                       /*
+                        * If adding an extra stream to an already
+                        * existing channel (e.g. cpu hotplug), we need
+                        * to send the "streams_sent" command to relayd.
+                        */
+                       if (channel->streams_sent_to_relayd) {
+                               ret = consumer_send_relayd_streams_sent(
+                                               new_stream->net_seq_idx);
+                               if (ret < 0) {
+                                       goto end_nosignal;
+                               }
+                       }
                }
 
                /* Get the right pipe where the stream will be sent. */
                if (new_stream->metadata_flag) {
-                       ret = consumer_add_metadata_stream(new_stream);
-                       if (ret) {
-                               ERR("Consumer add metadata stream %" PRIu64 " failed. Continuing",
-                                               new_stream->key);
-                               consumer_stream_free(new_stream);
-                               goto end_nosignal;
-                       }
+                       consumer_add_metadata_stream(new_stream);
                        stream_pipe = ctx->consumer_metadata_pipe;
                } else {
-                       ret = consumer_add_data_stream(new_stream);
-                       if (ret) {
-                               ERR("Consumer add stream %" PRIu64 " failed. Continuing",
-                                               new_stream->key);
-                               consumer_stream_free(new_stream);
-                               goto end_nosignal;
-                       }
+                       consumer_add_data_stream(new_stream);
                        stream_pipe = ctx->consumer_data_pipe;
                }
 
-               /* Vitible to other threads */
+               /* Visible to other threads */
                new_stream->globally_visible = 1;
 
                health_code_update();
@@ -767,8 +775,8 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        goto end_nosignal;
                }
 
-               DBG("Kernel consumer ADD_STREAM %s (fd: %d) with relayd id %" PRIu64,
-                               new_stream->name, fd, new_stream->relayd_stream_id);
+               DBG("Kernel consumer ADD_STREAM %s (fd: %d) %s with relayd id %" PRIu64,
+                               new_stream->name, fd, new_stream->chan->pathname, new_stream->relayd_stream_id);
                break;
        }
        case LTTNG_CONSUMER_STREAMS_SENT:
@@ -819,6 +827,7 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                        if (ret < 0) {
                                goto end_nosignal;
                        }
+                       channel->streams_sent_to_relayd = true;
                }
                break;
        }
@@ -964,27 +973,28 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        }
        case LTTNG_CONSUMER_DISCARDED_EVENTS:
        {
-               uint64_t ret;
+               ssize_t ret;
+               uint64_t count;
                struct lttng_consumer_channel *channel;
                uint64_t id = msg.u.discarded_events.session_id;
                uint64_t key = msg.u.discarded_events.channel_key;
 
+               DBG("Kernel consumer discarded events command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
                channel = consumer_find_channel(key);
                if (!channel) {
                        ERR("Kernel consumer discarded events channel %"
                                        PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+                       count = 0;
+               } else {
+                       count = channel->discarded_events;
                }
 
-               DBG("Kernel consumer discarded events command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               ret = channel->discarded_events;
-
                health_code_update();
 
                /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
                if (ret < 0) {
                        PERROR("send discarded events");
                        goto error_fatal;
@@ -994,32 +1004,250 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
        }
        case LTTNG_CONSUMER_LOST_PACKETS:
        {
-               uint64_t ret;
+               ssize_t ret;
+               uint64_t count;
                struct lttng_consumer_channel *channel;
                uint64_t id = msg.u.lost_packets.session_id;
                uint64_t key = msg.u.lost_packets.channel_key;
 
+               DBG("Kernel consumer lost packets command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
                channel = consumer_find_channel(key);
                if (!channel) {
                        ERR("Kernel consumer lost packets channel %"
                                        PRIu64 " not found", key);
+                       count = 0;
+               } else {
+                       count = channel->lost_packets;
+               }
+
+               health_code_update();
+
+               /* Send back returned value to session daemon */
+               ret = lttcomm_send_unix_sock(sock, &count, sizeof(count));
+               if (ret < 0) {
+                       PERROR("send lost packets");
+                       goto error_fatal;
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_SET_CHANNEL_MONITOR_PIPE:
+       {
+               int channel_monitor_pipe;
+
+               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               /* Successfully received the command's type. */
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       goto error_fatal;
+               }
+
+               ret = lttcomm_recv_fds_unix_sock(sock, &channel_monitor_pipe,
+                               1);
+               if (ret != sizeof(channel_monitor_pipe)) {
+                       ERR("Failed to receive channel monitor pipe");
+                       goto error_fatal;
+               }
+
+               DBG("Received channel monitor pipe (%d)", channel_monitor_pipe);
+               ret = consumer_timer_thread_set_channel_monitor_pipe(
+                               channel_monitor_pipe);
+               if (!ret) {
+                       int flags;
+
+                       ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+                       /* Set the pipe as non-blocking. */
+                       ret = fcntl(channel_monitor_pipe, F_GETFL, 0);
+                       if (ret == -1) {
+                               PERROR("fcntl get flags of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       flags = ret;
+
+                       ret = fcntl(channel_monitor_pipe, F_SETFL,
+                                       flags | O_NONBLOCK);
+                       if (ret == -1) {
+                               PERROR("fcntl set O_NONBLOCK flag of the channel monitoring pipe");
+                               goto error_fatal;
+                       }
+                       DBG("Channel monitor pipe set as non-blocking");
+               } else {
+                       ret_code = LTTCOMM_CONSUMERD_ALREADY_SET;
+               }
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       goto error_fatal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_SET_CHANNEL_ROTATE_PIPE:
+       {
+               int channel_rotate_pipe;
+               int flags;
+
+               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               /* Successfully received the command's type. */
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       goto error_fatal;
+               }
+
+               ret = lttcomm_recv_fds_unix_sock(sock, &channel_rotate_pipe, 1);
+               if (ret != (ssize_t) sizeof(channel_rotate_pipe)) {
+                       ERR("Failed to receive channel rotate pipe");
+                       goto error_fatal;
+               }
+
+               DBG("Received channel rotate pipe (%d)", channel_rotate_pipe);
+               ctx->channel_rotate_pipe = channel_rotate_pipe;
+               /* Set the pipe as non-blocking. */
+               ret = fcntl(channel_rotate_pipe, F_GETFL, 0);
+               if (ret == -1) {
+                       PERROR("fcntl get flags of the channel rotate pipe");
+                       goto error_fatal;
+               }
+               flags = ret;
+
+               ret = fcntl(channel_rotate_pipe, F_SETFL, flags | O_NONBLOCK);
+               if (ret == -1) {
+                       PERROR("fcntl set O_NONBLOCK flag of the channel rotate pipe");
+                       goto error_fatal;
+               }
+               DBG("Channel rotate pipe set as non-blocking");
+               ret_code = LTTCOMM_CONSUMERD_SUCCESS;
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       goto error_fatal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_ROTATE_CHANNEL:
+       {
+               DBG("Consumer rotate channel %" PRIu64, msg.u.rotate_channel.key);
+
+               /*
+                * Sample the rotate position of all the streams in this channel.
+                */
+               ret = lttng_consumer_rotate_channel(msg.u.rotate_channel.key,
+                               msg.u.rotate_channel.pathname,
+                               msg.u.rotate_channel.relayd_id,
+                               msg.u.rotate_channel.metadata,
+                               msg.u.rotate_channel.new_chunk_id,
+                               ctx);
+               if (ret < 0) {
+                       ERR("Rotate channel failed");
                        ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
                }
 
-               DBG("Kernel consumer lost packets command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
+               health_code_update();
+
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+
+               /* Rotate the streams that are ready right now. */
+               ret = lttng_consumer_rotate_ready_streams(
+                               msg.u.rotate_channel.key, ctx);
+               if (ret < 0) {
+                       ERR("Rotate ready streams failed");
+               }
+
+               break;
+       }
+       case LTTNG_CONSUMER_ROTATE_RENAME:
+       {
+               DBG("Consumer rename session %" PRIu64 " after rotation, old path = \"%s\", new path = \"%s\"",
+                               msg.u.rotate_rename.session_id,
+                               msg.u.rotate_rename.old_path,
+                               msg.u.rotate_rename.new_path);
+               ret = lttng_consumer_rotate_rename(msg.u.rotate_rename.old_path,
+                               msg.u.rotate_rename.new_path,
+                               msg.u.rotate_rename.uid,
+                               msg.u.rotate_rename.gid,
+                               msg.u.rotate_rename.relayd_id);
+               if (ret < 0) {
+                       ERR("Rotate rename failed");
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
 
-               ret = channel->lost_packets;
+               health_code_update();
+
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+               break;
+       }
+       case LTTNG_CONSUMER_ROTATE_PENDING_RELAY:
+       {
+               int pending;
+               uint32_t pending_reply;
+
+               DBG("Consumer rotate pending on relay for session %" PRIu64,
+                               msg.u.rotate_pending_relay.session_id);
+               pending = lttng_consumer_rotate_pending_relay(
+                               msg.u.rotate_pending_relay.session_id,
+                               msg.u.rotate_pending_relay.relayd_id,
+                               msg.u.rotate_pending_relay.chunk_id);
+               if (pending < 0) {
+                       ERR("Rotate pending relay failed");
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               } else {
+                       pending_reply = !!pending;
+               }
 
                health_code_update();
 
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
+
+               if (pending < 0) {
+                       /*
+                        * An error occured while running the command;
+                        * don't send the 'pending' flag as the sessiond
+                        * will not read it.
+                        */
+                       break;
+               }
+
                /* Send back returned value to session daemon */
-               ret = lttcomm_send_unix_sock(sock, &ret, sizeof(ret));
+               ret = lttcomm_send_unix_sock(sock, &pending_reply,
+                               sizeof(pending_reply));
                if (ret < 0) {
-                       PERROR("send lost packets");
+                       PERROR("send data pending ret code");
                        goto error_fatal;
                }
+               break;
+       }
+       case LTTNG_CONSUMER_MKDIR:
+       {
+               DBG("Consumer mkdir %s in session %" PRIu64,
+                               msg.u.mkdir.path,
+                               msg.u.mkdir.session_id);
+               ret = lttng_consumer_mkdir(msg.u.mkdir.path,
+                               msg.u.mkdir.uid,
+                               msg.u.mkdir.gid,
+                               msg.u.mkdir.relayd_id);
+               if (ret < 0) {
+                       ERR("consumer mkdir failed");
+                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+               }
 
+               health_code_update();
+
+               ret = consumer_send_status_msg(sock, ret_code);
+               if (ret < 0) {
+                       /* Somehow, the session daemon is not responding anymore. */
+                       goto end_nosignal;
+               }
                break;
        }
        default:
@@ -1095,15 +1323,26 @@ static int get_index_values(struct ctf_packet_index *index, int infd)
 
        ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
        if (ret < 0) {
-               PERROR("kernctl_get_instance_id");
-               goto error;
+               if (ret == -ENOTTY) {
+                       /* Command not implemented by lttng-modules. */
+                       index->stream_instance_id = -1ULL;
+               } else {
+                       PERROR("kernctl_get_instance_id");
+                       goto error;
+               }
        }
        index->stream_instance_id = htobe64(index->stream_instance_id);
 
        ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
        if (ret < 0) {
-               PERROR("kernctl_get_sequence_number");
-               goto error;
+               if (ret == -ENOTTY) {
+                       /* Command not implemented by lttng-modules. */
+                       index->packet_seq_num = -1ULL;
+                       ret = 0;
+               } else {
+                       PERROR("kernctl_get_sequence_number");
+                       goto error;
+               }
        }
        index->packet_seq_num = htobe64(index->packet_seq_num);
 
@@ -1133,7 +1372,7 @@ int lttng_kconsumer_sync_metadata(struct lttng_consumer_stream *metadata)
 
        ret = kernctl_snapshot(metadata->wait_fd);
        if (ret < 0) {
-               if (errno != EAGAIN) {
+               if (ret != -EAGAIN) {
                        ERR("Sync metadata, taking kernel snapshot failed.");
                        goto end;
                }
@@ -1155,8 +1394,13 @@ int update_stream_stats(struct lttng_consumer_stream *stream)
 
        ret = kernctl_get_sequence_number(stream->wait_fd, &seq);
        if (ret < 0) {
-               PERROR("kernctl_get_sequence_number");
-               goto end;
+               if (ret == -ENOTTY) {
+                       /* Command not implemented by lttng-modules. */
+                       seq = -1ULL;
+               } else {
+                       PERROR("kernctl_get_sequence_number");
+                       goto end;
+               }
        }
 
        /*
@@ -1186,8 +1430,8 @@ int update_stream_stats(struct lttng_consumer_stream *stream)
        }
        if (discarded < stream->last_discarded_events) {
                /*
-                * Overflow has occured. We assume only one wrap-around
-                * has occured.
+                * Overflow has occurred. We assume only one wrap-around
+                * has occurred.
                 */
                stream->chan->discarded_events += (1ULL << (CAA_BITS_PER_LONG - 1)) -
                        stream->last_discarded_events + discarded;
@@ -1202,20 +1446,73 @@ end:
        return ret;
 }
 
+/*
+ * Check if the local version of the metadata stream matches with the version
+ * of the metadata stream in the kernel. If it was updated, set the reset flag
+ * on the stream.
+ */
+static
+int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
+{
+       int ret;
+       uint64_t cur_version;
+
+       ret = kernctl_get_metadata_version(infd, &cur_version);
+       if (ret < 0) {
+               if (ret == -ENOTTY) {
+                       /*
+                        * LTTng-modules does not implement this
+                        * command.
+                        */
+                       ret = 0;
+                       goto end;
+               }
+               ERR("Failed to get the metadata version");
+               goto end;
+       }
+
+       if (stream->metadata_version == cur_version) {
+               ret = 0;
+               goto end;
+       }
+
+       DBG("New metadata version detected");
+       stream->metadata_version = cur_version;
+       stream->reset_metadata_flag = 1;
+       ret = 0;
+
+end:
+       return ret;
+}
+
 /*
  * Consume data on a file descriptor and write it on a trace file.
  */
 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
-               struct lttng_consumer_local_data *ctx)
+               struct lttng_consumer_local_data *ctx, bool *rotated)
 {
        unsigned long len, subbuf_size, padding;
-       int err, write_index = 1;
+       int err, write_index = 1, rotation_ret;
        ssize_t ret = 0;
        int infd = stream->wait_fd;
        struct ctf_packet_index index;
 
        DBG("In read_subbuffer (infd : %d)", infd);
 
+       /*
+        * If the stream was flagged to be ready for rotation before we extract the
+        * next packet, rotate it now.
+        */
+       if (stream->rotate_ready) {
+               DBG("Rotate stream before extracting data");
+               rotation_ret = lttng_consumer_rotate_stream(ctx, stream, rotated);
+               if (rotation_ret < 0) {
+                       ERR("Stream rotation error");
+                       ret = -1;
+                       goto error;
+               }
+       }
+
        /* Get the next subbuffer */
        err = kernctl_get_next_subbuf(infd);
        if (err != 0) {
@@ -1227,8 +1524,8 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                 */
                DBG("Reserving sub buffer failed (everything is normal, "
                                "it is due to concurrency)");
-               ret = -errno;
-               goto end;
+               ret = err;
+               goto error;
        }
 
        /* Get the full subbuffer size including padding */
@@ -1237,17 +1534,17 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                PERROR("Getting sub-buffer len failed.");
                err = kernctl_put_subbuf(infd);
                if (err != 0) {
-                       if (errno == EFAULT) {
+                       if (err == -EFAULT) {
                                PERROR("Error in unreserving sub buffer\n");
-                       } else if (errno == EIO) {
+                       } else if (err == -EIO) {
                                /* Should never happen with newer LTTng versions */
                                PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
                        }
-                       ret = -errno;
-                       goto end;
+                       ret = err;
+                       goto error;
                }
-               ret = -errno;
-               goto end;
+               ret = err;
+               goto error;
        }
 
        if (!stream->metadata_flag) {
@@ -1255,23 +1552,49 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                if (ret < 0) {
                        err = kernctl_put_subbuf(infd);
                        if (err != 0) {
-                               if (errno == EFAULT) {
+                               if (err == -EFAULT) {
                                        PERROR("Error in unreserving sub buffer\n");
-                               } else if (errno == EIO) {
+                               } else if (err == -EIO) {
                                        /* Should never happen with newer LTTng versions */
                                        PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
                                }
-                               ret = -errno;
-                               goto end;
+                               ret = err;
+                               goto error;
                        }
-                       goto end;
+                       goto error;
                }
                ret = update_stream_stats(stream);
                if (ret < 0) {
-                       goto end;
+                       err = kernctl_put_subbuf(infd);
+                       if (err != 0) {
+                               if (err == -EFAULT) {
+                                       PERROR("Error in unreserving sub buffer\n");
+                               } else if (err == -EIO) {
+                                       /* Should never happen with newer LTTng versions */
+                                       PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
+                               }
+                               ret = err;
+                               goto error;
+                       }
+                       goto error;
                }
        } else {
                write_index = 0;
+               ret = metadata_stream_check_version(infd, stream);
+               if (ret < 0) {
+                       err = kernctl_put_subbuf(infd);
+                       if (err != 0) {
+                               if (err == -EFAULT) {
+                                       PERROR("Error in unreserving sub buffer\n");
+                               } else if (err == -EIO) {
+                                       /* Should never happen with newer LTTng versions */
+                                       PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
+                               }
+                               ret = err;
+                               goto error;
+                       }
+                       goto error;
+               }
        }
 
        switch (stream->chan->output) {
@@ -1308,17 +1631,17 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        PERROR("Getting sub-buffer len failed.");
                        err = kernctl_put_subbuf(infd);
                        if (err != 0) {
-                               if (errno == EFAULT) {
+                               if (err == -EFAULT) {
                                        PERROR("Error in unreserving sub buffer\n");
-                               } else if (errno == EIO) {
+                               } else if (err == -EIO) {
                                        /* Should never happen with newer LTTng versions */
                                        PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
                                }
-                               ret = -errno;
-                               goto end;
+                               ret = err;
+                               goto error;
                        }
-                       ret = -errno;
-                       goto end;
+                       ret = err;
+                       goto error;
                }
 
                /* Make sure the tracer is not gone mad on us! */
@@ -1354,19 +1677,19 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
 
        err = kernctl_put_next_subbuf(infd);
        if (err != 0) {
-               if (errno == EFAULT) {
+               if (err == -EFAULT) {
                        PERROR("Error in unreserving sub buffer\n");
-               } else if (errno == EIO) {
+               } else if (err == -EIO) {
                        /* Should never happen with newer LTTng versions */
                        PERROR("Reader has been pushed by the writer, last sub-buffer corrupted.");
                }
-               ret = -errno;
-               goto end;
+               ret = err;
+               goto error;
        }
 
        /* Write index if needed. */
        if (!write_index) {
-               goto end;
+               goto rotate;
        }
 
        if (stream->chan->live_timer_interval && !stream->metadata_flag) {
@@ -1390,16 +1713,35 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        pthread_mutex_unlock(&stream->metadata_timer_lock);
                }
                if (err < 0) {
-                       goto end;
+                       goto error;
                }
        }
 
        err = consumer_stream_write_index(stream, &index);
        if (err < 0) {
-               goto end;
+               goto error;
        }
 
-end:
+rotate:
+       /*
+        * After extracting the packet, we check if the stream is now ready to be
+        * rotated and perform the action immediately.
+        */
+       rotation_ret = lttng_consumer_stream_is_rotate_ready(stream);
+       if (rotation_ret == 1) {
+               rotation_ret = lttng_consumer_rotate_stream(ctx, stream, rotated);
+               if (rotation_ret < 0) {
+                       ERR("Stream rotation error");
+                       ret = -1;
+                       goto error;
+               }
+       } else if (rotation_ret < 0) {
+               ERR("Checking if stream is ready to rotate");
+               ret = -1;
+               goto error;
+       }
+
+error:
        return ret;
 }
 
@@ -1424,14 +1766,18 @@ int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
                stream->tracefile_size_current = 0;
 
                if (!stream->metadata_flag) {
-                       ret = index_create_file(stream->chan->pathname,
+                       struct lttng_index_file *index_file;
+
+                       index_file = lttng_index_file_create(stream->chan->pathname,
                                        stream->name, stream->uid, stream->gid,
                                        stream->chan->tracefile_size,
-                                       stream->tracefile_count_current);
-                       if (ret < 0) {
+                                       stream->tracefile_count_current,
+                                       CTF_INDEX_MAJOR, CTF_INDEX_MINOR);
+                       if (!index_file) {
                                goto error;
                        }
-                       stream->index_fd = ret;
+                       assert(!stream->index_file);
+                       stream->index_file = index_file;
                }
        }
 
@@ -1442,7 +1788,6 @@ int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
                ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
                if (ret != 0) {
                        PERROR("kernctl_get_mmap_len");
-                       ret = -errno;
                        goto error_close_fd;
                }
                stream->mmap_len = (size_t) mmap_len;
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