relayd: logging of `trace chunk exists` command refers to the wrong command
[lttng-tools.git] / src / bin / lttng-relayd / main.c
index 44ea6cdeee8cd06baf8e0127032de7fc0b4aed03..a250100d12acc7e8ca87f6dc4108642f8c6b1a73 100644 (file)
@@ -1,21 +1,11 @@
 /*
- * Copyright (C) 2012 Julien Desfossez <jdesfossez@efficios.com>
- *                      David Goulet <dgoulet@efficios.com>
- *               2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
- *               2015 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2012 Julien Desfossez <jdesfossez@efficios.com>
+ * Copyright (C) 2012 David Goulet <dgoulet@efficios.com>
+ * Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ * Copyright (C) 2015 Mathieu Desnoyers <mathieu.desnoyers@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,
- * as published by the Free Software Foundation.
+ * SPDX-License-Identifier: GPL-2.0-only
  *
- * This program is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along
- * with this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #define _LGPL_SOURCE
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/resource.h>
 #include <inttypes.h>
 #include <urcu/futex.h>
 #include <urcu/uatomic.h>
+#include <urcu/rculist.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <strings.h>
+#include <ctype.h>
 
 #include <lttng/lttng.h>
 #include <common/common.h>
 #include <common/config/session-config.h>
 #include <common/dynamic-buffer.h>
 #include <common/buffer-view.h>
-#include <urcu/rculist.h>
+#include <common/string-utils/format.h>
+#include <common/fd-tracker/fd-tracker.h>
+#include <common/fd-tracker/utils.h>
 
+#include "backward-compatibility-group-by.h"
 #include "cmd.h"
+#include "connection.h"
 #include "ctf-trace.h"
+#include "health-relayd.h"
 #include "index.h"
-#include "utils.h"
-#include "lttng-relayd.h"
 #include "live.h"
-#include "health-relayd.h"
-#include "testpoint.h"
-#include "viewer-stream.h"
+#include "lttng-relayd.h"
 #include "session.h"
+#include "sessiond-trace-chunks.h"
 #include "stream.h"
-#include "connection.h"
-#include "tracefile-array.h"
 #include "tcp_keep_alive.h"
+#include "testpoint.h"
+#include "tracefile-array.h"
+#include "utils.h"
+#include "version.h"
+#include "viewer-stream.h"
 
 static const char *help_msg =
 #ifdef LTTNG_EMBED_HELP
@@ -83,9 +82,18 @@ NULL
 #endif
 ;
 
+enum relay_connection_status {
+       RELAY_CONNECTION_STATUS_OK,
+       /* An error occurred while processing an event on the connection. */
+       RELAY_CONNECTION_STATUS_ERROR,
+       /* Connection closed/shutdown cleanly. */
+       RELAY_CONNECTION_STATUS_CLOSED,
+};
+
 /* command line options */
-char *opt_output_path;
-static int opt_daemon, opt_background;
+char *opt_output_path, *opt_working_directory;
+static int opt_daemon, opt_background, opt_print_version, opt_allow_clear = 1;
+enum relay_group_output_by opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_UNKNOWN;
 
 /*
  * We need to wait for listener and live listener threads, as well as
@@ -96,7 +104,6 @@ static int lttng_relay_ready = NR_LTTNG_RELAY_READY;
 
 /* Size of receive buffer. */
 #define RECV_DATA_BUFFER_SIZE          65536
-#define FILE_COPY_BUFFER_SIZE          65536
 
 static int recv_child_signal;  /* Set to 1 when a SIGUSR1 signal is received. */
 static pid_t child_ppid;       /* Internal parent PID use with daemonize. */
@@ -147,6 +154,9 @@ static uint64_t last_relay_stream_id;
  */
 static struct relay_conn_queue relay_conn_queue;
 
+/* Cap of file desriptors to be in simultaneous use by the relay daemon. */
+static unsigned int lttng_opt_fd_pool_size = -1;
+
 /* Global relay stream hash table. */
 struct lttng_ht *relay_streams_ht;
 
@@ -159,6 +169,11 @@ struct lttng_ht *sessions_ht;
 /* Relayd health monitoring */
 struct health_app *health_relayd;
 
+struct sessiond_trace_chunk_registry *sessiond_trace_chunk_registry;
+
+/* Global fd tracker. */
+struct fd_tracker *the_fd_tracker;
+
 static struct option long_options[] = {
        { "control-port", 1, 0, 'C', },
        { "data-port", 1, 0, 'D', },
@@ -166,16 +181,38 @@ static struct option long_options[] = {
        { "daemonize", 0, 0, 'd', },
        { "background", 0, 0, 'b', },
        { "group", 1, 0, 'g', },
+       { "fd-pool-size", 1, 0, '\0', },
        { "help", 0, 0, 'h', },
        { "output", 1, 0, 'o', },
        { "verbose", 0, 0, 'v', },
        { "config", 1, 0, 'f' },
        { "version", 0, 0, 'V' },
+       { "working-directory", 1, 0, 'w', },
+       { "group-output-by-session", 0, 0, 's', },
+       { "group-output-by-host", 0, 0, 'p', },
+       { "disallow-clear", 0, 0, 'x' },
        { NULL, 0, 0, 0, },
 };
 
 static const char *config_ignore_options[] = { "help", "config", "version" };
 
+static void print_version(void) {
+       fprintf(stdout, "%s\n", VERSION);
+}
+
+static void relayd_config_log(void)
+{
+       DBG("LTTng-relayd " VERSION " - " VERSION_NAME "%s%s",
+                       GIT_VERSION[0] == '\0' ? "" : " - " GIT_VERSION,
+                       EXTRA_VERSION_NAME[0] == '\0' ? "" : " - " EXTRA_VERSION_NAME);
+       if (EXTRA_VERSION_DESCRIPTION[0] != '\0') {
+               DBG("LTTng-relayd extra version description:\n\t" EXTRA_VERSION_DESCRIPTION "\n");
+       }
+       if (EXTRA_VERSION_PATCHES[0] != '\0') {
+               DBG("LTTng-relayd extra patches:\n\t" EXTRA_VERSION_PATCHES "\n");
+       }
+}
+
 /*
  * Take an option from the getopt output and set it in the right variable to be
  * used later.
@@ -188,9 +225,27 @@ static int set_option(int opt, const char *arg, const char *optname)
 
        switch (opt) {
        case 0:
-               fprintf(stderr, "option %s", optname);
-               if (arg) {
-                       fprintf(stderr, " with arg %s\n", arg);
+               if (!strcmp(optname, "fd-pool-size")) {
+                       unsigned long v;
+
+                       errno = 0;
+                       v = strtoul(arg, NULL, 0);
+                       if (errno != 0 || !isdigit((unsigned char) arg[0])) {
+                               ERR("Wrong value in --fd-pool-size parameter: %s", arg);
+                               ret = -1;
+                               goto end;
+                       }
+                       if (v >= UINT_MAX) {
+                               ERR("File descriptor cap overflow in --fd-pool-size parameter: %s", arg);
+                               ret = -1;
+                               goto end;
+                       }
+                       lttng_opt_fd_pool_size = (unsigned int) v;
+               } else {
+                       fprintf(stderr, "unknown option %s", optname);
+                       if (arg) {
+                               fprintf(stderr, " with arg %s\n", arg);
+                       }
                }
                break;
        case 'C':
@@ -266,8 +321,8 @@ static int set_option(int opt, const char *arg, const char *optname)
                }
                exit(EXIT_FAILURE);
        case 'V':
-               fprintf(stdout, "%s\n", VERSION);
-               exit(EXIT_SUCCESS);
+               opt_print_version = 1;
+               break;
        case 'o':
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
@@ -281,6 +336,20 @@ static int set_option(int opt, const char *arg, const char *optname)
                        }
                }
                break;
+       case 'w':
+               if (lttng_is_setuid_setgid()) {
+                       WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
+                               "-w, --working-directory");
+               } else {
+                       ret = asprintf(&opt_working_directory, "%s", arg);
+                       if (ret < 0) {
+                               ret = -errno;
+                               PERROR("asprintf opt_working_directory");
+                               goto end;
+                       }
+               }
+               break;
+
        case 'v':
                /* Verbose level can increase using multiple -v */
                if (arg) {
@@ -292,6 +361,24 @@ static int set_option(int opt, const char *arg, const char *optname)
                        }
                }
                break;
+       case 's':
+               if (opt_group_output_by != RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+                       ERR("Cannot set --group-output-by-session, another --group-output-by argument is present");
+                       exit(EXIT_FAILURE);
+               }
+               opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_SESSION;
+               break;
+       case 'p':
+               if (opt_group_output_by != RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+                       ERR("Cannot set --group-output-by-host, another --group-output-by argument is present");
+                       exit(EXIT_FAILURE);
+               }
+               opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_HOST;
+               break;
+       case 'x':
+               /* Disallow clear */
+               opt_allow_clear = 0;
+               break;
        default:
                /* Unknown option or other error.
                 * Error is printed by getopt, just return */
@@ -361,6 +448,73 @@ end:
        return ret;
 }
 
+static int parse_env_options(void)
+{
+       int ret = 0;
+       char *value = NULL;
+
+       value = lttng_secure_getenv(DEFAULT_LTTNG_RELAYD_WORKING_DIRECTORY_ENV);
+       if (value) {
+               opt_working_directory = strdup(value);
+               if (!opt_working_directory) {
+                       ERR("Failed to allocate working directory string (\"%s\")",
+                                       value);
+                       ret = -1;
+               }
+       }
+       return ret;
+}
+
+static int set_fd_pool_size(void)
+{
+       int ret = 0;
+       struct rlimit rlimit;
+
+       ret = getrlimit(RLIMIT_NOFILE, &rlimit);
+       if (ret) {
+               PERROR("Failed to get file descriptor limit");
+               ret = -1;
+               goto end;
+       }
+
+       DBG("File descriptor count limits are %" PRIu64 " (soft) and %" PRIu64 " (hard)",
+                       (uint64_t) rlimit.rlim_cur,
+                       (uint64_t) rlimit.rlim_max);
+       if (lttng_opt_fd_pool_size == -1) {
+               /* Use default value (soft limit - reserve). */
+               if (rlimit.rlim_cur < DEFAULT_RELAYD_MIN_FD_POOL_SIZE) {
+                       ERR("The process' file number limit is too low (%" PRIu64 "). The process' file number limit must be set to at least %i.",
+                                       (uint64_t) rlimit.rlim_cur, DEFAULT_RELAYD_MIN_FD_POOL_SIZE);
+                       ret = -1;
+                       goto end;
+               }
+               lttng_opt_fd_pool_size = rlimit.rlim_cur -
+                               DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE;
+               goto end;
+       }
+
+       if (lttng_opt_fd_pool_size < DEFAULT_RELAYD_MIN_FD_POOL_SIZE) {
+               ERR("File descriptor pool size must be set to at least %d",
+                               DEFAULT_RELAYD_MIN_FD_POOL_SIZE);
+               ret = -1;
+               goto end;
+       }
+
+       if (lttng_opt_fd_pool_size > rlimit.rlim_cur) {
+               ERR("File descriptor pool size argument (%u) exceeds the process' soft limit (%" PRIu64 ").",
+                               lttng_opt_fd_pool_size, (uint64_t) rlimit.rlim_cur);
+               ret = -1;
+               goto end;
+       }
+
+       DBG("File descriptor pool size argument (%u) adjusted to %u to accommodates transient fd uses",
+                       lttng_opt_fd_pool_size,
+                       lttng_opt_fd_pool_size - DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE);
+       lttng_opt_fd_pool_size -= DEFAULT_RELAYD_FD_POOL_SIZE_RESERVE;
+end:
+       return ret;
+}
+
 static int set_options(int argc, char **argv)
 {
        int c, ret = 0, option_index = 0, retval = 0;
@@ -478,6 +632,28 @@ static int set_options(int argc, char **argv)
                        goto exit;
                }
        }
+       ret = set_fd_pool_size();
+       if (ret) {
+               retval = -1;
+               goto exit;
+       }
+
+       if (opt_group_output_by == RELAYD_GROUP_OUTPUT_BY_UNKNOWN) {
+               opt_group_output_by = RELAYD_GROUP_OUTPUT_BY_HOST;
+       }
+       if (opt_allow_clear) {
+               /* Check if env variable exists. */
+               const char *value = lttng_secure_getenv(DEFAULT_LTTNG_RELAYD_DISALLOW_CLEAR_ENV);
+               if (value) {
+                       ret = config_parse_value(value);
+                       if (ret < 0) {
+                               ERR("Invalid value for %s specified", DEFAULT_LTTNG_RELAYD_DISALLOW_CLEAR_ENV);
+                               retval = -1;
+                               goto exit;
+                       }
+                       opt_allow_clear = !ret;
+               }
+       }
 
 exit:
        free(optstring);
@@ -486,13 +662,26 @@ exit:
 
 static void print_global_objects(void)
 {
-       rcu_register_thread();
-
        print_viewer_streams();
        print_relay_streams();
        print_sessions();
+}
 
-       rcu_unregister_thread();
+static int noop_close(void *data, int *fds)
+{
+       return 0;
+}
+
+static void untrack_stdio(void)
+{
+       int fds[] = { fileno(stdout), fileno(stderr) };
+
+       /*
+        * noop_close is used since we don't really want to close
+        * the stdio output fds; we merely want to stop tracking them.
+        */
+       (void) fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+                       fds, 2, noop_close, NULL);
 }
 
 /*
@@ -511,11 +700,33 @@ static void relayd_cleanup(void)
        if (sessions_ht)
                lttng_ht_destroy(sessions_ht);
 
-       /* free the dynamically allocated opt_output_path */
        free(opt_output_path);
+       free(opt_working_directory);
 
+       if (health_relayd) {
+               health_app_destroy(health_relayd);
+       }
        /* Close thread quit pipes */
-       utils_close_pipe(thread_quit_pipe);
+       if (health_quit_pipe[0] != -1) {
+               (void) fd_tracker_util_pipe_close(
+                               the_fd_tracker, health_quit_pipe);
+       }
+       if (thread_quit_pipe[0] != -1) {
+               (void) fd_tracker_util_pipe_close(
+                               the_fd_tracker, thread_quit_pipe);
+       }
+       if (sessiond_trace_chunk_registry) {
+               sessiond_trace_chunk_registry_destroy(
+                               sessiond_trace_chunk_registry);
+       }
+       if (the_fd_tracker) {
+               untrack_stdio();
+               /*
+                * fd_tracker_destroy() will log the contents of the fd-tracker
+                * if a leak is detected.
+                */
+               fd_tracker_destroy(the_fd_tracker);
+       }
 
        uri_free(control_uri);
        uri_free(data_uri);
@@ -677,17 +888,26 @@ void lttng_relay_notify_ready(void)
  */
 static int init_thread_quit_pipe(void)
 {
-       int ret;
-
-       ret = utils_create_pipe_cloexec(thread_quit_pipe);
+       return fd_tracker_util_pipe_open_cloexec(
+                       the_fd_tracker, "Quit pipe", thread_quit_pipe);
+}
 
-       return ret;
+/*
+ * Init health quit pipe.
+ *
+ * Return -1 on error or 0 if all pipes are created.
+ */
+static int init_health_quit_pipe(void)
+{
+       return fd_tracker_util_pipe_open_cloexec(the_fd_tracker,
+                       "Health quit pipe", health_quit_pipe);
 }
 
 /*
  * Create a poll set with O_CLOEXEC and add the thread quit pipe to the set.
  */
-static int create_thread_poll_set(struct lttng_poll_event *events, int size)
+static int create_named_thread_poll_set(struct lttng_poll_event *events,
+               int size, const char *name)
 {
        int ret;
 
@@ -696,8 +916,10 @@ static int create_thread_poll_set(struct lttng_poll_event *events, int size)
                goto error;
        }
 
-       ret = lttng_poll_create(events, size, LTTNG_CLOEXEC);
-       if (ret < 0) {
+       ret = fd_tracker_util_poll_create(the_fd_tracker,
+                       name, events, 1, LTTNG_CLOEXEC);
+       if (ret) {
+               PERROR("Failed to create \"%s\" poll file descriptor", name);
                goto error;
        }
 
@@ -727,13 +949,55 @@ static int check_thread_quit_pipe(int fd, uint32_t events)
        return 0;
 }
 
+static int create_sock(void *data, int *out_fd)
+{
+       int ret;
+       struct lttcomm_sock *sock = data;
+
+       ret = lttcomm_create_sock(sock);
+       if (ret < 0) {
+               goto end;
+       }
+
+       *out_fd = sock->fd;
+end:
+       return ret;
+}
+
+static int close_sock(void *data, int *in_fd)
+{
+       struct lttcomm_sock *sock = data;
+
+       return sock->ops->close(sock);
+}
+
+static int accept_sock(void *data, int *out_fd)
+{
+       int ret = 0;
+       /* Socks is an array of in_sock, out_sock. */
+       struct lttcomm_sock **socks = data;
+       struct lttcomm_sock *in_sock = socks[0];
+
+       socks[1] = in_sock->ops->accept(in_sock);
+       if (!socks[1]) {
+               ret = -1;
+               goto end;
+       }
+       *out_fd = socks[1]->fd;
+end:
+       return ret;
+}
+
 /*
  * Create and init socket from uri.
  */
-static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri)
+static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri,
+               const char *name)
 {
-       int ret;
+       int ret, sock_fd;
        struct lttcomm_sock *sock = NULL;
+       char uri_str[PATH_MAX];
+       char *formated_name = NULL;
 
        sock = lttcomm_alloc_sock_from_uri(uri);
        if (sock == NULL) {
@@ -741,11 +1005,29 @@ static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri)
                goto error;
        }
 
-       ret = lttcomm_create_sock(sock);
-       if (ret < 0) {
+       /*
+        * Don't fail to create the socket if the name can't be built as it is
+        * only used for debugging purposes.
+        */
+       ret = uri_to_str_url(uri, uri_str, sizeof(uri_str));
+       uri_str[sizeof(uri_str) - 1] = '\0';
+       if (ret >= 0) {
+               ret = asprintf(&formated_name, "%s socket @ %s", name,
+                               uri_str);
+               if (ret < 0) {
+                       formated_name = NULL;
+               }
+       }
+
+       ret = fd_tracker_open_unsuspendable_fd(the_fd_tracker, &sock_fd,
+                       (const char **) (formated_name ? &formated_name : NULL),
+                       1, create_sock, sock);
+       if (ret) {
+               PERROR("Failed to open \"%s\" relay socket",
+                               formated_name ?: "Unknown");
                goto error;
        }
-       DBG("Listening on sock %d", sock->fd);
+       DBG("Listening on %s socket %d", name, sock->fd);
 
        ret = sock->ops->bind(sock);
        if (ret < 0) {
@@ -759,15 +1041,38 @@ static struct lttcomm_sock *relay_socket_create(struct lttng_uri *uri)
 
        }
 
+       free(formated_name);
        return sock;
 
 error:
        if (sock) {
                lttcomm_destroy_sock(sock);
        }
+       free(formated_name);
        return NULL;
 }
 
+static
+struct lttcomm_sock *accept_relayd_sock(struct lttcomm_sock *listening_sock,
+               const char *name)
+{
+       int out_fd, ret;
+       struct lttcomm_sock *socks[2] = { listening_sock, NULL };
+       struct lttcomm_sock *new_sock = NULL;
+
+       ret = fd_tracker_open_unsuspendable_fd(
+                       the_fd_tracker, &out_fd,
+                       (const char **) &name,
+                       1, accept_sock, &socks);
+       if (ret) {
+               goto end;
+       }
+       new_sock = socks[1];
+       DBG("%s accepted, socket %d", name, new_sock->fd);
+end:
+       return new_sock;
+}
+
 /*
  * This thread manages the listening for new connections on the network
  */
@@ -780,16 +1085,17 @@ static void *relay_thread_listener(void *data)
 
        DBG("[thread] Relay listener started");
 
+       rcu_register_thread();
        health_register(health_relayd, HEALTH_RELAYD_TYPE_LISTENER);
 
        health_code_update();
 
-       control_sock = relay_socket_create(control_uri);
+       control_sock = relay_socket_create(control_uri, "Control listener");
        if (!control_sock) {
                goto error_sock_control;
        }
 
-       data_sock = relay_socket_create(data_uri);
+       data_sock = relay_socket_create(data_uri, "Data listener");
        if (!data_sock) {
                goto error_sock_relay;
        }
@@ -798,7 +1104,7 @@ static void *relay_thread_listener(void *data)
         * Pass 3 as size here for the thread quit pipe, control and
         * data socket.
         */
-       ret = create_thread_poll_set(&events, 3);
+       ret = create_named_thread_poll_set(&events, 3, "Listener thread epoll");
        if (ret < 0) {
                goto error_create_poll;
        }
@@ -850,14 +1156,6 @@ restart:
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);
 
-                       if (!revents) {
-                               /*
-                                * No activity for this FD (poll
-                                * implementation).
-                                */
-                               continue;
-                       }
-
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -874,20 +1172,18 @@ restart:
                                 */
                                int val = 1;
                                struct relay_connection *new_conn;
-                               struct lttcomm_sock *newsock;
+                               struct lttcomm_sock *newsock = NULL;
                                enum connection_type type;
 
                                if (pollfd == data_sock->fd) {
                                        type = RELAY_DATA;
-                                       newsock = data_sock->ops->accept(data_sock);
-                                       DBG("Relay data connection accepted, socket %d",
-                                                       newsock->fd);
+                                       newsock = accept_relayd_sock(data_sock,
+                                                       "Data socket to relayd");
                                } else {
                                        assert(pollfd == control_sock->fd);
                                        type = RELAY_CONTROL;
-                                       newsock = control_sock->ops->accept(control_sock);
-                                       DBG("Relay control connection accepted, socket %d",
-                                                       newsock->fd);
+                                       newsock = accept_relayd_sock(control_sock,
+                                                       "Control socket to relayd");
                                }
                                if (!newsock) {
                                        PERROR("accepting sock");
@@ -940,21 +1236,31 @@ exit:
 error:
 error_poll_add:
 error_testpoint:
-       lttng_poll_clean(&events);
+       (void) fd_tracker_util_poll_clean(the_fd_tracker, &events);
 error_create_poll:
        if (data_sock->fd >= 0) {
-               ret = data_sock->ops->close(data_sock);
+               int data_sock_fd = data_sock->fd;
+
+               ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+                               &data_sock_fd, 1, close_sock,
+                               data_sock);
                if (ret) {
-                       PERROR("close");
+                       PERROR("Failed to close the data listener socket file descriptor");
                }
+               data_sock->fd = -1;
        }
        lttcomm_destroy_sock(data_sock);
 error_sock_relay:
        if (control_sock->fd >= 0) {
-               ret = control_sock->ops->close(control_sock);
+               int control_sock_fd = control_sock->fd;
+
+               ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker,
+                               &control_sock_fd, 1, close_sock,
+                               control_sock);
                if (ret) {
-                       PERROR("close");
+                       PERROR("Failed to close the control listener socket file descriptor");
                }
+               control_sock->fd = -1;
        }
        lttcomm_destroy_sock(control_sock);
 error_sock_control:
@@ -963,6 +1269,7 @@ error_sock_control:
                ERR("Health error occurred in %s", __func__);
        }
        health_unregister(health_relayd);
+       rcu_unregister_thread();
        DBG("Relay listener thread cleanup complete");
        lttng_relay_stop_threads();
        return NULL;
@@ -1048,31 +1355,9 @@ error_testpoint:
        return NULL;
 }
 
-/*
- * Set index data from the control port to a given index object.
- */
-static int set_index_control_data(struct relay_index *index,
-               struct lttcomm_relayd_index *data,
-               struct relay_connection *conn)
+static bool session_streams_have_index(const struct relay_session *session)
 {
-       struct ctf_packet_index index_data;
-
-       /*
-        * The index on disk is encoded in big endian.
-        */
-       index_data.packet_size = htobe64(data->packet_size);
-       index_data.content_size = htobe64(data->content_size);
-       index_data.timestamp_begin = htobe64(data->timestamp_begin);
-       index_data.timestamp_end = htobe64(data->timestamp_end);
-       index_data.events_discarded = htobe64(data->events_discarded);
-       index_data.stream_id = htobe64(data->stream_id);
-
-       if (conn->minor >= 8) {
-               index->index_data.stream_instance_id = htobe64(data->stream_instance_id);
-               index->index_data.packet_seq_num = htobe64(data->packet_seq_num);
-       }
-
-       return relay_index_set_data(index, &index_data);
+       return session->minor >= 4 && !session->snapshot;
 }
 
 /*
@@ -1086,34 +1371,67 @@ static int relay_create_session(const struct lttcomm_relayd_hdr *recv_hdr,
 {
        int ret = 0;
        ssize_t send_ret;
-       struct relay_session *session;
-       struct lttcomm_relayd_status_session reply;
-       char session_name[LTTNG_NAME_MAX];
-       char hostname[LTTNG_HOST_NAME_MAX];
+       struct relay_session *session = NULL;
+       struct lttcomm_relayd_create_session_reply_2_11 reply = {};
+       char session_name[LTTNG_NAME_MAX] = {};
+       char hostname[LTTNG_HOST_NAME_MAX] = {};
        uint32_t live_timer = 0;
        bool snapshot = false;
-
-       memset(session_name, 0, LTTNG_NAME_MAX);
-       memset(hostname, 0, LTTNG_HOST_NAME_MAX);
-
-       memset(&reply, 0, sizeof(reply));
-
-       switch (conn->minor) {
-       case 1:
-       case 2:
-       case 3:
-               break;
-       case 4: /* LTTng sessiond 2.4 */
-       default:
+       bool session_name_contains_creation_timestamp = false;
+       /* Left nil for peers < 2.11. */
+       char base_path[LTTNG_PATH_MAX] = {};
+       lttng_uuid sessiond_uuid = {};
+       LTTNG_OPTIONAL(uint64_t) id_sessiond = {};
+       LTTNG_OPTIONAL(uint64_t) current_chunk_id = {};
+       LTTNG_OPTIONAL(time_t) creation_time = {};
+       struct lttng_dynamic_buffer reply_payload;
+
+       lttng_dynamic_buffer_init(&reply_payload);
+
+       if (conn->minor < 4) {
+               /* From 2.1 to 2.3 */
+               ret = 0;
+       } else if (conn->minor >= 4 && conn->minor < 11) {
+               /* From 2.4 to 2.10 */
                ret = cmd_create_session_2_4(payload, session_name,
                        hostname, &live_timer, &snapshot);
+       } else {
+               bool has_current_chunk;
+               uint64_t current_chunk_id_value;
+               time_t creation_time_value;
+               uint64_t id_sessiond_value;
+
+               /* From 2.11 to ... */
+               ret = cmd_create_session_2_11(payload, session_name, hostname,
+                               base_path, &live_timer, &snapshot, &id_sessiond_value,
+                               sessiond_uuid, &has_current_chunk,
+                               &current_chunk_id_value, &creation_time_value,
+                               &session_name_contains_creation_timestamp);
+               if (lttng_uuid_is_nil(sessiond_uuid)) {
+                       /* The nil UUID is reserved for pre-2.11 clients. */
+                       ERR("Illegal nil UUID announced by peer in create session command");
+                       ret = -1;
+                       goto send_reply;
+               }
+               LTTNG_OPTIONAL_SET(&id_sessiond, id_sessiond_value);
+               LTTNG_OPTIONAL_SET(&creation_time, creation_time_value);
+               if (has_current_chunk) {
+                       LTTNG_OPTIONAL_SET(&current_chunk_id,
+                                       current_chunk_id_value);
+               }
        }
+
        if (ret < 0) {
                goto send_reply;
        }
 
-       session = session_create(session_name, hostname, live_timer,
-                       snapshot, conn->major, conn->minor);
+       session = session_create(session_name, hostname, base_path, live_timer,
+                       snapshot, sessiond_uuid,
+                       id_sessiond.is_set ? &id_sessiond.value : NULL,
+                       current_chunk_id.is_set ? &current_chunk_id.value : NULL,
+                       creation_time.is_set ? &creation_time.value : NULL,
+                       conn->major, conn->minor,
+                       session_name_contains_creation_timestamp);
        if (!session) {
                ret = -1;
                goto send_reply;
@@ -1122,22 +1440,59 @@ static int relay_create_session(const struct lttcomm_relayd_hdr *recv_hdr,
        conn->session = session;
        DBG("Created session %" PRIu64, session->id);
 
-       reply.session_id = htobe64(session->id);
+       reply.generic.session_id = htobe64(session->id);
 
 send_reply:
        if (ret < 0) {
-               reply.ret_code = htobe32(LTTNG_ERR_FATAL);
+               reply.generic.ret_code = htobe32(LTTNG_ERR_FATAL);
        } else {
-               reply.ret_code = htobe32(LTTNG_OK);
+               reply.generic.ret_code = htobe32(LTTNG_OK);
        }
 
-       send_ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
-       if (send_ret < (ssize_t) sizeof(reply)) {
-               ERR("Failed to send \"create session\" command reply (ret = %zd)",
-                               send_ret);
-               ret = -1;
+       if (conn->minor < 11) {
+               /* From 2.1 to 2.10 */
+               ret = lttng_dynamic_buffer_append(&reply_payload,
+                               &reply.generic, sizeof(reply.generic));
+               if (ret) {
+                       ERR("Failed to append \"create session\" command reply header to payload buffer");
+                       ret = -1;
+                       goto end;
+               }
+       } else {
+               const uint32_t output_path_length =
+                               session ? strlen(session->output_path) + 1 : 0;
+
+               reply.output_path_length = htobe32(output_path_length);
+               ret = lttng_dynamic_buffer_append(
+                               &reply_payload, &reply, sizeof(reply));
+               if (ret) {
+                       ERR("Failed to append \"create session\" command reply header to payload buffer");
+                       goto end;
+               }
+
+               if (output_path_length) {
+                       ret = lttng_dynamic_buffer_append(&reply_payload,
+                                       session->output_path,
+                                       output_path_length);
+                       if (ret) {
+                               ERR("Failed to append \"create session\" command reply path to payload buffer");
+                               goto end;
+                       }
+               }
        }
 
+       send_ret = conn->sock->ops->sendmsg(conn->sock, reply_payload.data,
+                       reply_payload.size, 0);
+       if (send_ret < (ssize_t) reply_payload.size) {
+               ERR("Failed to send \"create session\" command reply of %zu bytes (ret = %zd)",
+                               reply_payload.size, send_ret);
+               ret = -1;
+       }
+end:
+       if (ret < 0 && session) {
+               session_put(session);
+       }
+       lttng_dynamic_buffer_reset(&reply_payload);
        return ret;
 }
 
@@ -1171,6 +1526,34 @@ static void publish_connection_local_streams(struct relay_connection *conn)
        pthread_mutex_unlock(&session->lock);
 }
 
+static int conform_channel_path(char *channel_path)
+{
+       int ret = 0;
+
+       if (strstr("../", channel_path)) {
+               ERR("Refusing channel path as it walks up the path hierarchy: \"%s\"",
+                               channel_path);
+               ret = -1;
+               goto end;
+       }
+
+       if (*channel_path == '/') {
+               const size_t len = strlen(channel_path);
+
+               /*
+                * Channel paths from peers prior to 2.11 are expressed as an
+                * absolute path that is, in reality, relative to the relay
+                * daemon's output directory. Remove the leading slash so it
+                * is correctly interpreted as a relative path later on.
+                *
+                * len (and not len - 1) is used to copy the trailing NULL.
+                */
+               bcopy(channel_path + 1, channel_path, len);
+       }
+end:
+       return ret;
+}
+
 /*
  * relay_add_stream: allocate a new stream for a session
  */
@@ -1187,6 +1570,7 @@ static int relay_add_stream(const struct lttcomm_relayd_hdr *recv_hdr,
        uint64_t stream_handle = -1ULL;
        char *path_name = NULL, *channel_name = NULL;
        uint64_t tracefile_size = 0, tracefile_count = 0;
+       LTTNG_OPTIONAL(uint64_t) stream_chunk_id = {};
 
        if (!session || !conn->version_check_done) {
                ERR("Trying to add a stream before version check");
@@ -1194,34 +1578,89 @@ static int relay_add_stream(const struct lttcomm_relayd_hdr *recv_hdr,
                goto end_no_session;
        }
 
-       switch (session->minor) {
-       case 1: /* LTTng sessiond 2.1. Allocates path_name and channel_name. */
+       if (session->minor == 1) {
+               /* For 2.1 */
                ret = cmd_recv_stream_2_1(payload, &path_name,
                        &channel_name);
-               break;
-       case 2: /* LTTng sessiond 2.2. Allocates path_name and channel_name. */
-       default:
+       } else if (session->minor > 1 && session->minor < 11) {
+               /* From 2.2 to 2.10 */
                ret = cmd_recv_stream_2_2(payload, &path_name,
                        &channel_name, &tracefile_size, &tracefile_count);
-               break;
+       } else {
+               /* From 2.11 to ... */
+               ret = cmd_recv_stream_2_11(payload, &path_name,
+                       &channel_name, &tracefile_size, &tracefile_count,
+                       &stream_chunk_id.value);
+               stream_chunk_id.is_set = true;
        }
+
        if (ret < 0) {
                goto send_reply;
        }
 
-       trace = ctf_trace_get_by_path_or_create(session, path_name);
-       if (!trace) {
+       if (conform_channel_path(path_name)) {
                goto send_reply;
        }
-       /* This stream here has one reference on the trace. */
 
-       pthread_mutex_lock(&last_relay_stream_id_lock);
+       /*
+        * Backward compatibility for --group-output-by-session.
+        * Prior to lttng 2.11, the complete path is passed by the stream.
+        * Starting at 2.11, lttng-relayd uses chunk. When dealing with producer
+        * >=2.11 the chunk is responsible for the output path. When dealing
+        * with producer < 2.11 the chunk output_path is the root output path
+        * and the stream carries the complete path (path_name).
+        * To support --group-output-by-session with older producer (<2.11), we
+        * need to craft the path based on the stream path.
+        */
+       if (opt_group_output_by == RELAYD_GROUP_OUTPUT_BY_SESSION) {
+               if (conn->minor < 4) {
+                       /*
+                        * From 2.1 to 2.3, the session_name is not passed on
+                        * the RELAYD_CREATE_SESSION command. The session name
+                        * is necessary to detect the presence of a base_path
+                        * inside the stream path. Without it we cannot perform
+                        * a valid group-output-by-session transformation.
+                        */
+                       WARN("Unable to perform a --group-by-session transformation for session %" PRIu64
+                            " for stream with path \"%s\" as it is produced by a peer using a protocol older than v2.4",
+                                       session->id, path_name);
+               } else if (conn->minor >= 4 && conn->minor < 11) {
+                       char *group_by_session_path_name;
+
+                       assert(session->session_name[0] != '\0');
+
+                       group_by_session_path_name =
+                                       backward_compat_group_by_session(
+                                                       path_name,
+                                                       session->session_name,
+                                                       session->creation_time.value);
+                       if (!group_by_session_path_name) {
+                               ERR("Failed to apply group by session to stream of session %" PRIu64,
+                                               session->id);
+                               goto send_reply;
+                       }
+
+                       DBG("Transformed session path from \"%s\" to \"%s\" to honor per-session name grouping",
+                                       path_name, group_by_session_path_name);
+
+                       free(path_name);
+                       path_name = group_by_session_path_name;
+               }
+       }
+
+       trace = ctf_trace_get_by_path_or_create(session, path_name);
+       if (!trace) {
+               goto send_reply;
+       }
+
+       /* This stream here has one reference on the trace. */
+       pthread_mutex_lock(&last_relay_stream_id_lock);
        stream_handle = ++last_relay_stream_id;
        pthread_mutex_unlock(&last_relay_stream_id_lock);
 
        /* We pass ownership of path_name and channel_name. */
        stream = stream_create(trace, stream_handle, path_name,
-                       channel_name, tracefile_size, tracefile_count);
+               channel_name, tracefile_size, tracefile_count);
        path_name = NULL;
        channel_name = NULL;
 
@@ -1314,7 +1753,7 @@ static int relay_close_stream(const struct lttcomm_relayd_hdr *recv_hdr,
 
                vstream = viewer_stream_get_by_id(stream->stream_handle);
                if (vstream) {
-                       if (vstream->metadata_sent == stream->metadata_received) {
+                       if (stream->no_new_metadata_notified) {
                                /*
                                 * Since all the metadata has been sent to the
                                 * viewer and that we have a request to close
@@ -1401,15 +1840,14 @@ int relay_reset_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
                goto end_unlock;
        }
 
-       ret = utils_rotate_stream_file(stream->path_name, stream->channel_name,
-                       0, 0, -1, -1, stream->stream_fd->fd, NULL,
-                       &stream->stream_fd->fd);
+       ret = stream_reset_file(stream);
        if (ret < 0) {
-               ERR("Failed to rotate metadata file %s of channel %s",
-                               stream->path_name, stream->channel_name);
+               ERR("Failed to reset metadata stream %" PRIu64
+                               ": stream_path = %s, channel = %s",
+                               stream->stream_handle, stream->path_name,
+                               stream->channel_name);
                goto end_unlock;
        }
-
 end_unlock:
        pthread_mutex_unlock(&stream->lock);
        stream_put(stream);
@@ -1480,280 +1918,6 @@ static int relay_start(const struct lttcomm_relayd_hdr *recv_hdr,
        return ret;
 }
 
-/*
- * Append padding to the file pointed by the file descriptor fd.
- */
-static int write_padding_to_file(int fd, uint32_t size)
-{
-       ssize_t ret = 0;
-       char *zeros;
-
-       if (size == 0) {
-               goto end;
-       }
-
-       zeros = zmalloc(size);
-       if (zeros == NULL) {
-               PERROR("zmalloc zeros for padding");
-               ret = -1;
-               goto end;
-       }
-
-       ret = lttng_write(fd, zeros, size);
-       if (ret < size) {
-               PERROR("write padding to file");
-       }
-
-       free(zeros);
-
-end:
-       return ret;
-}
-
-/*
- * Close the current index file if it is open, and create a new one.
- *
- * Return 0 on success, -1 on error.
- */
-static
-int create_rotate_index_file(struct relay_stream *stream)
-{
-       int ret;
-       uint32_t major, minor;
-
-       /* Put ref on previous index_file. */
-       if (stream->index_file) {
-               lttng_index_file_put(stream->index_file);
-               stream->index_file = NULL;
-       }
-       major = stream->trace->session->major;
-       minor = stream->trace->session->minor;
-       stream->index_file = lttng_index_file_create(stream->path_name,
-                       stream->channel_name,
-                       -1, -1, stream->tracefile_size,
-                       tracefile_array_get_file_index_head(stream->tfa),
-                       lttng_to_index_major(major, minor),
-                       lttng_to_index_minor(major, minor));
-       if (!stream->index_file) {
-               ret = -1;
-               goto end;
-       }
-
-       ret = 0;
-
-end:
-       return ret;
-}
-
-static
-int do_rotate_stream(struct relay_stream *stream)
-{
-       int ret;
-
-       /* Perform the stream rotation. */
-       ret = utils_rotate_stream_file(stream->path_name,
-                       stream->channel_name, stream->tracefile_size,
-                       stream->tracefile_count, -1,
-                       -1, stream->stream_fd->fd,
-                       NULL, &stream->stream_fd->fd);
-       if (ret < 0) {
-               ERR("Rotating stream output file");
-               goto end;
-       }
-       stream->tracefile_size_current = 0;
-
-       /* Rotate also the index if the stream is not a metadata stream. */
-       if (!stream->is_metadata) {
-               ret = create_rotate_index_file(stream);
-               if (ret < 0) {
-                       ERR("Failed to rotate index file");
-                       goto end;
-               }
-       }
-
-       stream->rotate_at_seq_num = -1ULL;
-       stream->pos_after_last_complete_data_index = 0;
-
-end:
-       return ret;
-}
-
-/*
- * If too much data has been written in a tracefile before we received the
- * rotation command, we have to move the excess data to the new tracefile and
- * perform the rotation. This can happen because the control and data
- * connections are separate, the indexes as well as the commands arrive from
- * the control connection and we have no control over the order so we could be
- * in a situation where too much data has been received on the data connection
- * before the rotation command on the control connection arrives. We don't need
- * to update the index because its order is guaranteed with the rotation
- * command message.
- */
-static
-int rotate_truncate_stream(struct relay_stream *stream)
-{
-       int ret, new_fd;
-       off_t lseek_ret;
-       uint64_t diff, pos = 0;
-       char buf[FILE_COPY_BUFFER_SIZE];
-
-       assert(!stream->is_metadata);
-
-       assert(stream->tracefile_size_current >
-                       stream->pos_after_last_complete_data_index);
-       diff = stream->tracefile_size_current -
-                       stream->pos_after_last_complete_data_index;
-
-       /* Create the new tracefile. */
-       new_fd = utils_create_stream_file(stream->path_name,
-                       stream->channel_name,
-                       stream->tracefile_size, stream->tracefile_count,
-                       /* uid */ -1, /* gid */ -1, /* suffix */ NULL);
-       if (new_fd < 0) {
-               ERR("Failed to create new stream file at path %s for channel %s",
-                               stream->path_name, stream->channel_name);
-               ret = -1;
-               goto end;
-       }
-
-       /*
-        * Rewind the current tracefile to the position at which the rotation
-        * should have occured.
-        */
-       lseek_ret = lseek(stream->stream_fd->fd,
-                       stream->pos_after_last_complete_data_index, SEEK_SET);
-       if (lseek_ret < 0) {
-               PERROR("seek truncate stream");
-               ret = -1;
-               goto end;
-       }
-
-       /* Move data from the old file to the new file. */
-       while (pos < diff) {
-               uint64_t count, bytes_left;
-               ssize_t io_ret;
-
-               bytes_left = diff - pos;
-               count = bytes_left > sizeof(buf) ? sizeof(buf) : bytes_left;
-               assert(count <= SIZE_MAX);
-
-               io_ret = lttng_read(stream->stream_fd->fd, buf, count);
-               if (io_ret < (ssize_t) count) {
-                       char error_string[256];
-
-                       snprintf(error_string, sizeof(error_string),
-                                       "Failed to read %" PRIu64 " bytes from fd %i in rotate_truncate_stream(), returned %zi",
-                                       count, stream->stream_fd->fd, io_ret);
-                       if (io_ret == -1) {
-                               PERROR("%s", error_string);
-                       } else {
-                               ERR("%s", error_string);
-                       }
-                       ret = -1;
-                       goto end;
-               }
-
-               io_ret = lttng_write(new_fd, buf, count);
-               if (io_ret < (ssize_t) count) {
-                       char error_string[256];
-
-                       snprintf(error_string, sizeof(error_string),
-                                       "Failed to write %" PRIu64 " bytes from fd %i in rotate_truncate_stream(), returned %zi",
-                                       count, new_fd, io_ret);
-                       if (io_ret == -1) {
-                               PERROR("%s", error_string);
-                       } else {
-                               ERR("%s", error_string);
-                       }
-                       ret = -1;
-                       goto end;
-               }
-
-               pos += count;
-       }
-
-       /* Truncate the file to get rid of the excess data. */
-       ret = ftruncate(stream->stream_fd->fd,
-                       stream->pos_after_last_complete_data_index);
-       if (ret) {
-               PERROR("ftruncate");
-               goto end;
-       }
-
-       ret = close(stream->stream_fd->fd);
-       if (ret < 0) {
-               PERROR("Closing tracefile");
-               goto end;
-       }
-
-       ret = create_rotate_index_file(stream);
-       if (ret < 0) {
-               ERR("Rotate stream index file");
-               goto end;
-       }
-
-       /*
-        * Update the offset and FD of all the eventual indexes created by the
-        * data connection before the rotation command arrived.
-        */
-       ret = relay_index_switch_all_files(stream);
-       if (ret < 0) {
-               ERR("Failed to rotate index file");
-               goto end;
-       }
-
-       stream->stream_fd->fd = new_fd;
-       stream->tracefile_size_current = diff;
-       stream->pos_after_last_complete_data_index = 0;
-       stream->rotate_at_seq_num = -1ULL;
-
-       ret = 0;
-
-end:
-       return ret;
-}
-
-/*
- * Check if a stream should perform a rotation (for session rotation).
- * Must be called with the stream lock held.
- *
- * Return 0 on success, a negative value on error.
- */
-static
-int try_rotate_stream(struct relay_stream *stream)
-{
-       int ret = 0;
-
-       /* No rotation expected. */
-       if (stream->rotate_at_seq_num == -1ULL) {
-               goto end;
-       }
-
-       if (stream->prev_seq < stream->rotate_at_seq_num ||
-                       stream->prev_seq == -1ULL) {
-               DBG("Stream %" PRIu64 " no yet ready for rotation",
-                               stream->stream_handle);
-               goto end;
-       } else if (stream->prev_seq > stream->rotate_at_seq_num) {
-               DBG("Rotation after too much data has been written in tracefile "
-                               "for stream %" PRIu64 ", need to truncate before "
-                               "rotating", stream->stream_handle);
-               ret = rotate_truncate_stream(stream);
-               if (ret) {
-                       ERR("Failed to truncate stream");
-                       goto end;
-               }
-       } else {
-               /* stream->prev_seq == stream->rotate_at_seq_num */
-               DBG("Stream %" PRIu64 " ready for rotation",
-                               stream->stream_handle);
-               ret = do_rotate_stream(stream);
-       }
-
-end:
-       return ret;
-}
-
 /*
  * relay_recv_metadata: receive the metadata for the session.
  */
@@ -1762,11 +1926,11 @@ static int relay_recv_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
                const struct lttng_buffer_view *payload)
 {
        int ret = 0;
-       ssize_t size_ret;
        struct relay_session *session = conn->session;
        struct lttcomm_relayd_metadata_payload metadata_payload_header;
        struct relay_stream *metadata_stream;
        uint64_t metadata_payload_size;
+       struct lttng_buffer_view packet_view;
 
        if (!session) {
                ERR("Metadata sent before version check");
@@ -1795,36 +1959,23 @@ static int relay_recv_metadata(const struct lttcomm_relayd_hdr *recv_hdr,
                goto end;
        }
 
-       pthread_mutex_lock(&metadata_stream->lock);
-
-       size_ret = lttng_write(metadata_stream->stream_fd->fd,
-                       payload->data + sizeof(metadata_payload_header),
-                       metadata_payload_size);
-       if (size_ret < metadata_payload_size) {
-               ERR("Relay error writing metadata on file");
+       packet_view = lttng_buffer_view_from_view(payload,
+                       sizeof(metadata_payload_header), metadata_payload_size);
+       if (!packet_view.data) {
+               ERR("Invalid metadata packet length announced by header");
                ret = -1;
                goto end_put;
        }
 
-       size_ret = write_padding_to_file(metadata_stream->stream_fd->fd,
+       pthread_mutex_lock(&metadata_stream->lock);
+       ret = stream_write(metadata_stream, &packet_view,
                        metadata_payload_header.padding_size);
-       if (size_ret < 0) {
+       pthread_mutex_unlock(&metadata_stream->lock);
+       if (ret){
                ret = -1;
                goto end_put;
        }
-
-       metadata_stream->metadata_received +=
-               metadata_payload_size + metadata_payload_header.padding_size;
-       DBG2("Relay metadata written. Updated metadata_received %" PRIu64,
-               metadata_stream->metadata_received);
-
-       ret = try_rotate_stream(metadata_stream);
-       if (ret < 0) {
-               goto end_put;
-       }
-
 end_put:
-       pthread_mutex_unlock(&metadata_stream->lock);
        stream_put(metadata_stream);
 end:
        return ret;
@@ -1913,6 +2064,7 @@ static int relay_data_pending(const struct lttcomm_relayd_hdr *recv_hdr,
        struct relay_stream *stream;
        ssize_t send_ret;
        int ret;
+       uint64_t stream_seq;
 
        DBG("Data pending command received");
 
@@ -1940,12 +2092,23 @@ static int relay_data_pending(const struct lttcomm_relayd_hdr *recv_hdr,
 
        pthread_mutex_lock(&stream->lock);
 
-       DBG("Data pending for stream id %" PRIu64 " prev_seq %" PRIu64
-                       " and last_seq %" PRIu64, msg.stream_id,
-                       stream->prev_seq, msg.last_net_seq_num);
+       if (session_streams_have_index(session)) {
+               /*
+                * Ensure that both the index and stream data have been
+                * flushed up to the requested point.
+                */
+               stream_seq = min(stream->prev_data_seq, stream->prev_index_seq);
+       } else {
+               stream_seq = stream->prev_data_seq;
+       }
+       DBG("Data pending for stream id %" PRIu64 ": prev_data_seq %" PRIu64
+                       ", prev_index_seq %" PRIu64
+                       ", and last_seq %" PRIu64, msg.stream_id,
+                       stream->prev_data_seq, stream->prev_index_seq,
+                       msg.last_net_seq_num);
 
        /* Avoid wrapping issue */
-       if (((int64_t) (stream->prev_seq - msg.last_net_seq_num)) >= 0) {
+       if (((int64_t) (stream_seq - msg.last_net_seq_num)) >= 0) {
                /* Data has in fact been written and is NOT pending */
                ret = 0;
        } else {
@@ -2165,7 +2328,18 @@ static int relay_end_data_pending(const struct lttcomm_relayd_hdr *recv_hdr,
                }
                pthread_mutex_lock(&stream->lock);
                if (!stream->data_pending_check_done) {
-                       if (!stream->closed || !(((int64_t) (stream->prev_seq - stream->last_net_seq_num)) >= 0)) {
+                       uint64_t stream_seq;
+
+                       if (session_streams_have_index(conn->session)) {
+                               /*
+                                * Ensure that both the index and stream data have been
+                                * flushed up to the requested point.
+                                */
+                               stream_seq = min(stream->prev_data_seq, stream->prev_index_seq);
+                       } else {
+                               stream_seq = stream->prev_data_seq;
+                       }
+                       if (!stream->closed || !(((int64_t) (stream_seq - stream->last_net_seq_num)) >= 0)) {
                                is_data_inflight = 1;
                                DBG("Data is still in flight for stream %" PRIu64,
                                                stream->stream_handle);
@@ -2209,7 +2383,6 @@ static int relay_recv_index(const struct lttcomm_relayd_hdr *recv_hdr,
        ssize_t send_ret;
        struct relay_session *session = conn->session;
        struct lttcomm_relayd_index index_info;
-       struct relay_index *index;
        struct lttcomm_relayd_generic_reply reply;
        struct relay_stream *stream;
        size_t msg_len;
@@ -2242,8 +2415,15 @@ static int relay_recv_index(const struct lttcomm_relayd_hdr *recv_hdr,
        index_info.timestamp_end = be64toh(index_info.timestamp_end);
        index_info.events_discarded = be64toh(index_info.events_discarded);
        index_info.stream_id = be64toh(index_info.stream_id);
-       index_info.stream_instance_id = be64toh(index_info.stream_instance_id);
-       index_info.packet_seq_num = be64toh(index_info.packet_seq_num);
+
+       if (conn->minor >= 8) {
+               index_info.stream_instance_id =
+                               be64toh(index_info.stream_instance_id);
+               index_info.packet_seq_num = be64toh(index_info.packet_seq_num);
+       } else {
+               index_info.stream_instance_id = -1ULL;
+               index_info.packet_seq_num = -1ULL;
+       }
 
        stream = stream_get_by_id(index_info.relay_stream_id);
        if (!stream) {
@@ -2251,62 +2431,17 @@ static int relay_recv_index(const struct lttcomm_relayd_hdr *recv_hdr,
                ret = -1;
                goto end;
        }
-       pthread_mutex_lock(&stream->lock);
-
-       /* Live beacon handling */
-       if (index_info.packet_size == 0) {
-               DBG("Received live beacon for stream %" PRIu64,
-                               stream->stream_handle);
-
-               /*
-                * Only flag a stream inactive when it has already
-                * received data and no indexes are in flight.
-                */
-               if (stream->index_received_seqcount > 0
-                               && stream->indexes_in_flight == 0) {
-                       stream->beacon_ts_end = index_info.timestamp_end;
-               }
-               ret = 0;
-               goto end_stream_put;
-       } else {
-               stream->beacon_ts_end = -1ULL;
-       }
 
-       if (stream->ctf_stream_id == -1ULL) {
-               stream->ctf_stream_id = index_info.stream_id;
-       }
-       index = relay_index_get_by_id_or_create(stream, index_info.net_seq_num);
-       if (!index) {
-               ret = -1;
-               ERR("relay_index_get_by_id_or_create index NULL");
-               goto end_stream_put;
-       }
-       if (set_index_control_data(index, &index_info, conn)) {
-               ERR("set_index_control_data error");
-               relay_index_put(index);
-               ret = -1;
+       pthread_mutex_lock(&stream->lock);
+       ret = stream_add_index(stream, &index_info);
+       pthread_mutex_unlock(&stream->lock);
+       if (ret) {
                goto end_stream_put;
        }
-       ret = relay_index_try_flush(index);
-       if (ret == 0) {
-               tracefile_array_commit_seq(stream->tfa);
-               stream->index_received_seqcount++;
-               stream->pos_after_last_complete_data_index += index->total_size;
-       } else if (ret > 0) {
-               /* no flush. */
-               ret = 0;
-       } else {
-               ERR("relay_index_try_flush error %d", ret);
-               relay_index_put(index);
-               ret = -1;
-       }
 
 end_stream_put:
-       pthread_mutex_unlock(&stream->lock);
        stream_put(stream);
-
 end:
-
        memset(&reply, 0, sizeof(reply));
        if (ret < 0) {
                reply.ret_code = htobe32(LTTNG_ERR_UNK);
@@ -2369,24 +2504,27 @@ end_no_session:
 }
 
 /*
- * relay_rotate_session_stream: rotate a stream to a new tracefile for the session
- * rotation feature (not the tracefile rotation feature).
+ * relay_rotate_session_stream: rotate a stream to a new tracefile for the
+ * session rotation feature (not the tracefile rotation feature).
  */
-static int relay_rotate_session_stream(const struct lttcomm_relayd_hdr *recv_hdr,
+static int relay_rotate_session_streams(
+               const struct lttcomm_relayd_hdr *recv_hdr,
                struct relay_connection *conn,
                const struct lttng_buffer_view *payload)
 {
-       int ret;
+       int ret = 0;
+       uint32_t i;
        ssize_t send_ret;
+       enum lttng_error_code reply_code = LTTNG_ERR_UNK;
        struct relay_session *session = conn->session;
-       struct lttcomm_relayd_rotate_stream stream_info;
-       struct lttcomm_relayd_generic_reply reply;
-       struct relay_stream *stream;
-       size_t header_len;
-       size_t path_len;
-       struct lttng_buffer_view new_path_view;
-
-       DBG("Rotate stream received");
+       struct lttcomm_relayd_rotate_streams rotate_streams;
+       struct lttcomm_relayd_generic_reply reply = {};
+       struct relay_stream *stream = NULL;
+       const size_t header_len = sizeof(struct lttcomm_relayd_rotate_streams);
+       struct lttng_trace_chunk *next_trace_chunk = NULL;
+       struct lttng_buffer_view stream_positions;
+       char chunk_id_buf[MAX_INT_DEC_LEN(uint64_t)];
+       const char *chunk_id_str = "none";
 
        if (!session || !conn->version_check_done) {
                ERR("Trying to rotate a stream before version check");
@@ -2400,8 +2538,6 @@ static int relay_rotate_session_stream(const struct lttcomm_relayd_hdr *recv_hdr
                goto end_no_reply;
        }
 
-       header_len = sizeof(struct lttcomm_relayd_rotate_stream);
-
        if (payload->size < header_len) {
                ERR("Unexpected payload size in \"relay_rotate_session_stream\": expected >= %zu bytes, got %zu bytes",
                                header_len, payload->size);
@@ -2409,87 +2545,101 @@ static int relay_rotate_session_stream(const struct lttcomm_relayd_hdr *recv_hdr
                goto end_no_reply;
        }
 
-       memcpy(&stream_info, payload->data, header_len);
+       memcpy(&rotate_streams, payload->data, header_len);
 
-       /* Convert to host */
-       stream_info.pathname_length = be32toh(stream_info.pathname_length);
-       stream_info.stream_id = be64toh(stream_info.stream_id);
-       stream_info.new_chunk_id = be64toh(stream_info.new_chunk_id);
-       stream_info.rotate_at_seq_num = be64toh(stream_info.rotate_at_seq_num);
+       /* Convert header to host endianness. */
+       rotate_streams = (typeof(rotate_streams)) {
+               .stream_count = be32toh(rotate_streams.stream_count),
+               .new_chunk_id = (typeof(rotate_streams.new_chunk_id)) {
+                       .is_set = !!rotate_streams.new_chunk_id.is_set,
+                       .value = be64toh(rotate_streams.new_chunk_id.value),
+               }
+       };
 
-       path_len = stream_info.pathname_length;
-       if (payload->size < header_len + path_len) {
-               ERR("Unexpected payload size in \"relay_rotate_session_stream\" including path: expected >= %zu bytes, got %zu bytes",
-                               header_len + path_len, payload->size);
-               ret = -1;
-               goto end_no_reply;
-       }       
-       
-       /* Ensure it fits in local filename length. */
-       if (path_len >= LTTNG_PATH_MAX) {
-               ret = -ENAMETOOLONG;
-               ERR("Length of relay_rotate_session_stream command's path name (%zu bytes) exceeds the maximal allowed length of %i bytes",
-                               path_len, LTTNG_PATH_MAX);
-               goto end;
+       if (rotate_streams.new_chunk_id.is_set) {
+               /*
+                * Retrieve the trace chunk the stream must transition to. As
+                * per the protocol, this chunk should have been created
+                * before this command is received.
+                */
+               next_trace_chunk = sessiond_trace_chunk_registry_get_chunk(
+                               sessiond_trace_chunk_registry,
+                               session->sessiond_uuid, session->id,
+                               rotate_streams.new_chunk_id.value);
+               if (!next_trace_chunk) {
+                       char uuid_str[LTTNG_UUID_STR_LEN];
+
+                       lttng_uuid_to_str(session->sessiond_uuid, uuid_str);
+                       ERR("Unknown next trace chunk in ROTATE_STREAMS command: sessiond_uuid = {%s}, session_id = %" PRIu64
+                                       ", trace_chunk_id = %" PRIu64,
+                                       uuid_str, session->id,
+                                       rotate_streams.new_chunk_id.value);
+                       reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+                       ret = -1;
+                       goto end;
+               }
+
+               ret = snprintf(chunk_id_buf, sizeof(chunk_id_buf), "%" PRIu64,
+                               rotate_streams.new_chunk_id.value);
+               if (ret < 0 || ret >= sizeof(chunk_id_buf)) {
+                       chunk_id_str = "formatting error";
+               } else {
+                       chunk_id_str = chunk_id_buf;
+               }
        }
 
-       new_path_view = lttng_buffer_view_from_view(payload, header_len,
-                       stream_info.pathname_length);
+       DBG("Rotate %" PRIu32 " streams of session \"%s\" to chunk \"%s\"",
+                       rotate_streams.stream_count, session->session_name,
+                       chunk_id_str);
 
-       stream = stream_get_by_id(stream_info.stream_id);
-       if (!stream) {
+       stream_positions = lttng_buffer_view_from_view(payload,
+                       sizeof(rotate_streams), -1);
+       if (!stream_positions.data ||
+                       stream_positions.size <
+                                       (rotate_streams.stream_count *
+                                                       sizeof(struct lttcomm_relayd_stream_rotation_position))) {
+               reply_code = LTTNG_ERR_INVALID_PROTOCOL;
                ret = -1;
                goto end;
        }
 
-       pthread_mutex_lock(&stream->lock);
+       for (i = 0; i < rotate_streams.stream_count; i++) {
+               struct lttcomm_relayd_stream_rotation_position *position_comm =
+                               &((typeof(position_comm)) stream_positions.data)[i];
+               const struct lttcomm_relayd_stream_rotation_position pos = {
+                       .stream_id = be64toh(position_comm->stream_id),
+                       .rotate_at_seq_num = be64toh(
+                                       position_comm->rotate_at_seq_num),
+               };
 
-       /*
-        * Update the trace path (just the folder, the stream name does not
-        * change).
-        */
-       free(stream->path_name);
-       stream->path_name = create_output_path(new_path_view.data);
-       if (!stream->path_name) {
-               ERR("Failed to create a new output path");
-               ret = -1;
-               goto end_stream_unlock;
-       }
-       ret = utils_mkdir_recursive(stream->path_name, S_IRWXU | S_IRWXG,
-                       -1, -1);
-       if (ret < 0) {
-               ERR("relay creating output directory");
-               ret = -1;
-               goto end_stream_unlock;
-       }
+               stream = stream_get_by_id(pos.stream_id);
+               if (!stream) {
+                       reply_code = LTTNG_ERR_INVALID;
+                       ret = -1;
+                       goto end;
+               }
 
-       stream->chunk_id = stream_info.new_chunk_id;
+               pthread_mutex_lock(&stream->lock);
+               ret = stream_set_pending_rotation(stream, next_trace_chunk,
+                               pos.rotate_at_seq_num);
+               pthread_mutex_unlock(&stream->lock);
+               if (ret) {
+                       reply_code = LTTNG_ERR_FILE_CREATION_ERROR;
+                       goto end;
+               }
 
-       if (stream->is_metadata) {
-               /*
-                * The metadata stream is sent only over the control connection
-                * so we know we have all the data to perform the stream
-                * rotation.
-                */
-               ret = do_rotate_stream(stream);
-       } else {
-               stream->rotate_at_seq_num = stream_info.rotate_at_seq_num;
-               ret = try_rotate_stream(stream);
-       }
-       if (ret < 0) {
-               goto end_stream_unlock;
+               stream_put(stream);
+               stream = NULL;
        }
 
-end_stream_unlock:
-       pthread_mutex_unlock(&stream->lock);
-       stream_put(stream);
+       reply_code = LTTNG_OK;
+       ret = 0;
 end:
-       memset(&reply, 0, sizeof(reply));
-       if (ret < 0) {
-               reply.ret_code = htobe32(LTTNG_ERR_UNK);
-       } else {
-               reply.ret_code = htobe32(LTTNG_OK);
+       if (stream) {
+               stream_put(stream);
        }
+
+       reply.ret_code = htobe32((uint32_t) reply_code);
        send_ret = conn->sock->ops->sendmsg(conn->sock, &reply,
                        sizeof(struct lttcomm_relayd_generic_reply), 0);
        if (send_ret < (ssize_t) sizeof(reply)) {
@@ -2497,360 +2647,559 @@ end:
                                send_ret);
                ret = -1;
        }
-
 end_no_reply:
+       lttng_trace_chunk_put(next_trace_chunk);
        return ret;
 }
 
+
+
 /*
- * relay_mkdir: Create a folder on the disk.
+ * relay_create_trace_chunk: create a new trace chunk
  */
-static int relay_mkdir(const struct lttcomm_relayd_hdr *recv_hdr,
+static int relay_create_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
                struct relay_connection *conn,
                const struct lttng_buffer_view *payload)
 {
-       int ret;
-       struct relay_session *session = conn->session;
-       struct lttcomm_relayd_mkdir path_info_header;
-       struct lttcomm_relayd_generic_reply reply;
-       char *path = NULL;
-       size_t header_len;
+       int ret = 0;
        ssize_t send_ret;
-       struct lttng_buffer_view path_view;
+       struct relay_session *session = conn->session;
+       struct lttcomm_relayd_create_trace_chunk *msg;
+       struct lttcomm_relayd_generic_reply reply = {};
+       struct lttng_buffer_view header_view;
+       struct lttng_buffer_view chunk_name_view;
+       struct lttng_trace_chunk *chunk = NULL, *published_chunk = NULL;
+       enum lttng_error_code reply_code = LTTNG_OK;
+       enum lttng_trace_chunk_status chunk_status;
+       const char *new_path;
 
        if (!session || !conn->version_check_done) {
-               ERR("Trying to create a directory before version check");
+               ERR("Trying to create a trace chunk before version check");
                ret = -1;
-               goto end_no_session;
+               goto end_no_reply;
        }
 
        if (session->major == 2 && session->minor < 11) {
-               /*
-                * This client is not supposed to use this command since
-                * it predates its introduction.
-                */
-               ERR("relay_mkdir command is unsupported before LTTng 2.11");
+               ERR("Chunk creation command is unsupported before 2.11");
                ret = -1;
-               goto end_no_session;
+               goto end_no_reply;
        }
 
-       header_len = sizeof(path_info_header);
-       if (payload->size < header_len) {
-               ERR("Unexpected payload size in \"relay_mkdir\": expected >= %zu bytes, got %zu bytes",
-                               header_len, payload->size);
+       header_view = lttng_buffer_view_from_view(payload, 0, sizeof(*msg));
+       if (!header_view.data) {
+               ERR("Failed to receive payload of chunk creation command");
                ret = -1;
-               goto end_no_session;
+               goto end_no_reply;
        }
 
-       memcpy(&path_info_header, payload->data, header_len);
-
-       path_info_header.length = be32toh(path_info_header.length);
+       /* Convert to host endianness. */
+       msg = (typeof(msg)) header_view.data;
+       msg->chunk_id = be64toh(msg->chunk_id);
+       msg->creation_timestamp = be64toh(msg->creation_timestamp);
+       msg->override_name_length = be32toh(msg->override_name_length);
 
-       if (payload->size < header_len + path_info_header.length) {
-               ERR("Unexpected payload size in \"relay_mkdir\" including path: expected >= %zu bytes, got %zu bytes",
-                               header_len + path_info_header.length, payload->size);
-               ret = -1;
-               goto end_no_session;
+       if (session->current_trace_chunk &&
+                       !lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
+               chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
+                                       DEFAULT_CHUNK_TMP_OLD_DIRECTORY);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ERR("Failed to rename old chunk");
+                       ret = -1;
+                       reply_code = LTTNG_ERR_UNK;
+                       goto end;
+               }
        }
-
-       /* Ensure that it fits in local path length. */
-       if (path_info_header.length >= LTTNG_PATH_MAX) {
-               ret = -ENAMETOOLONG;
-               ERR("Path name argument of mkdir command (%" PRIu32 " bytes) exceeds the maximal length allowed (%d bytes)",
-                               path_info_header.length, LTTNG_PATH_MAX);
+       session->ongoing_rotation = true;
+       if (!session->current_trace_chunk) {
+               if (!session->has_rotated) {
+                       new_path = "";
+               } else {
+                       new_path = NULL;
+               }
+       } else {
+               new_path = DEFAULT_CHUNK_TMP_NEW_DIRECTORY;
+       }
+       chunk = lttng_trace_chunk_create(
+                       msg->chunk_id, msg->creation_timestamp, new_path);
+       if (!chunk) {
+               ERR("Failed to create trace chunk in trace chunk creation command");
+               ret = -1;
+               reply_code = LTTNG_ERR_NOMEM;
                goto end;
        }
+       lttng_trace_chunk_set_fd_tracker(chunk, the_fd_tracker);
 
-       path_view = lttng_buffer_view_from_view(payload, header_len,
-                       path_info_header.length);
+       if (msg->override_name_length) {
+               const char *name;
 
-       path = create_output_path(path_view.data);
-       if (!path) {
-               ERR("Failed to create output path");
+               chunk_name_view = lttng_buffer_view_from_view(payload,
+                               sizeof(*msg),
+                               msg->override_name_length);
+               name = chunk_name_view.data;
+               if (!name || name[msg->override_name_length - 1]) {
+                       ERR("Failed to receive payload of chunk creation command");
+                       ret = -1;
+                       reply_code = LTTNG_ERR_INVALID;
+                       goto end;
+               }
+
+               chunk_status = lttng_trace_chunk_override_name(
+                               chunk, chunk_name_view.data);
+               switch (chunk_status) {
+               case LTTNG_TRACE_CHUNK_STATUS_OK:
+                       break;
+               case LTTNG_TRACE_CHUNK_STATUS_INVALID_ARGUMENT:
+                       ERR("Failed to set the name of new trace chunk in trace chunk creation command (invalid name)");
+                       reply_code = LTTNG_ERR_INVALID;
+                       ret = -1;
+                       goto end;
+               default:
+                       ERR("Failed to set the name of new trace chunk in trace chunk creation command (unknown error)");
+                       reply_code = LTTNG_ERR_UNK;
+                       ret = -1;
+                       goto end;
+               }
+       }
+
+       chunk_status = lttng_trace_chunk_set_credentials_current_user(chunk);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               reply_code = LTTNG_ERR_UNK;
                ret = -1;
                goto end;
        }
 
-       ret = utils_mkdir_recursive(path, S_IRWXU | S_IRWXG, -1, -1);
-       if (ret < 0) {
-               ERR("relay creating output directory");
+       assert(conn->session->output_directory);
+       chunk_status = lttng_trace_chunk_set_as_owner(chunk,
+                       conn->session->output_directory);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               reply_code = LTTNG_ERR_UNK;
+               ret = -1;
                goto end;
        }
 
-       ret = 0;
+       published_chunk = sessiond_trace_chunk_registry_publish_chunk(
+                       sessiond_trace_chunk_registry,
+                       conn->session->sessiond_uuid,
+                       conn->session->id,
+                       chunk);
+       if (!published_chunk) {
+               char uuid_str[LTTNG_UUID_STR_LEN];
 
-end:
-       memset(&reply, 0, sizeof(reply));
-       if (ret < 0) {
-               reply.ret_code = htobe32(LTTNG_ERR_UNK);
-       } else {
-               reply.ret_code = htobe32(LTTNG_OK);
-       }
-       send_ret = conn->sock->ops->sendmsg(conn->sock, &reply, sizeof(reply), 0);
-       if (send_ret < (ssize_t) sizeof(reply)) {
-               ERR("Failed to send \"mkdir\" command reply (ret = %zd)", send_ret);
+               lttng_uuid_to_str(conn->session->sessiond_uuid, uuid_str);
+               ERR("Failed to publish chunk: sessiond_uuid = %s, session_id = %" PRIu64 ", chunk_id = %" PRIu64,
+                               uuid_str,
+                               conn->session->id,
+                               msg->chunk_id);
                ret = -1;
+               reply_code = LTTNG_ERR_NOMEM;
+               goto end;
        }
 
-end_no_session:
-       free(path);
-       return ret;
-}
-
-static int validate_rotate_rename_path_length(const char *path_type,
-               uint32_t path_length)
-{
-       int ret = 0;
-
-       if (path_length > LTTNG_PATH_MAX) {
-               ret = -ENAMETOOLONG;
-               ERR("rotate rename \"%s\" path name length (%" PRIu32 " bytes) exceeds the allowed size of %i bytes",
-                               path_type, path_length, LTTNG_PATH_MAX);
-       } else if (path_length == 0) {
-               ret = -EINVAL;
-               ERR("rotate rename \"%s\" path name has an illegal length of 0", path_type);
+       pthread_mutex_lock(&conn->session->lock);
+       if (conn->session->pending_closure_trace_chunk) {
+               /*
+                * Invalid; this means a second create_trace_chunk command was
+                * received before a close_trace_chunk.
+                */
+               ERR("Invalid trace chunk close command received; a trace chunk is already waiting for a trace chunk close command");
+               reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+               ret = -1;
+               goto end_unlock_session;
+       }
+       conn->session->pending_closure_trace_chunk =
+                       conn->session->current_trace_chunk;
+       conn->session->current_trace_chunk = published_chunk;
+       published_chunk = NULL;
+       if (!conn->session->pending_closure_trace_chunk) {
+               session->ongoing_rotation = false;
+       }
+end_unlock_session:
+       pthread_mutex_unlock(&conn->session->lock);
+end:
+       reply.ret_code = htobe32((uint32_t) reply_code);
+       send_ret = conn->sock->ops->sendmsg(conn->sock,
+                       &reply,
+                       sizeof(struct lttcomm_relayd_generic_reply),
+                       0);
+       if (send_ret < (ssize_t) sizeof(reply)) {
+               ERR("Failed to send \"create trace chunk\" command reply (ret = %zd)",
+                               send_ret);
+               ret = -1;
        }
+end_no_reply:
+       lttng_trace_chunk_put(chunk);
+       lttng_trace_chunk_put(published_chunk);
        return ret;
 }
 
 /*
- * relay_rotate_rename: rename the trace folder after a rotation is
- * completed. We are not closing any fd here, just moving the folder, so it
- * works even if data is still in-flight.
+ * relay_close_trace_chunk: close a trace chunk
  */
-static int relay_rotate_rename(const struct lttcomm_relayd_hdr *recv_hdr,
+static int relay_close_trace_chunk(const struct lttcomm_relayd_hdr *recv_hdr,
                struct relay_connection *conn,
                const struct lttng_buffer_view *payload)
 {
-       int ret;
+       int ret = 0, buf_ret;
        ssize_t send_ret;
        struct relay_session *session = conn->session;
-       struct lttcomm_relayd_generic_reply reply;
-       struct lttcomm_relayd_rotate_rename header;
-       size_t header_len;
-       size_t received_paths_size;
-       char *complete_old_path = NULL, *complete_new_path = NULL;
-       struct lttng_buffer_view old_path_view;
-       struct lttng_buffer_view new_path_view;
+       struct lttcomm_relayd_close_trace_chunk *msg;
+       struct lttcomm_relayd_close_trace_chunk_reply reply = {};
+       struct lttng_buffer_view header_view;
+       struct lttng_trace_chunk *chunk = NULL;
+       enum lttng_error_code reply_code = LTTNG_OK;
+       enum lttng_trace_chunk_status chunk_status;
+       uint64_t chunk_id;
+       LTTNG_OPTIONAL(enum lttng_trace_chunk_command_type) close_command = {};
+       time_t close_timestamp;
+       char closed_trace_chunk_path[LTTNG_PATH_MAX];
+       size_t path_length = 0;
+       const char *chunk_name = NULL;
+       struct lttng_dynamic_buffer reply_payload;
+       const char *new_path;
+
+       lttng_dynamic_buffer_init(&reply_payload);
 
        if (!session || !conn->version_check_done) {
-               ERR("Trying to rename a trace folder before version check");
+               ERR("Trying to close a trace chunk before version check");
                ret = -1;
                goto end_no_reply;
        }
 
        if (session->major == 2 && session->minor < 11) {
-               ERR("relay_rotate_rename command is unsupported before LTTng 2.11");
+               ERR("Chunk close command is unsupported before 2.11");
                ret = -1;
                goto end_no_reply;
        }
 
-       header_len = sizeof(header);
-       if (payload->size < header_len) {
-               ERR("Unexpected payload size in \"relay_rotate_rename\": expected >= %zu bytes, got %zu bytes",
-                               header_len, payload->size);
+       header_view = lttng_buffer_view_from_view(payload, 0, sizeof(*msg));
+       if (!header_view.data) {
+               ERR("Failed to receive payload of chunk close command");
                ret = -1;
                goto end_no_reply;
        }
 
-       memcpy(&header, payload->data, header_len);
-
-       header.old_path_length = be32toh(header.old_path_length);
-       header.new_path_length = be32toh(header.new_path_length);
-       received_paths_size = header.old_path_length + header.new_path_length;
-
-       if (payload->size < header_len + received_paths_size) {
-               ERR("Unexpected payload size in \"relay_rotate_rename\" including paths: expected >= %zu bytes, got %zu bytes",
-                               header_len, payload->size);
+       /* Convert to host endianness. */
+       msg = (typeof(msg)) header_view.data;
+       chunk_id = be64toh(msg->chunk_id);
+       close_timestamp = (time_t) be64toh(msg->close_timestamp);
+       close_command = (typeof(close_command)){
+               .value = be32toh(msg->close_command.value),
+               .is_set = msg->close_command.is_set,
+       };
+
+       chunk = sessiond_trace_chunk_registry_get_chunk(
+                       sessiond_trace_chunk_registry,
+                       conn->session->sessiond_uuid,
+                       conn->session->id,
+                       chunk_id);
+       if (!chunk) {
+               char uuid_str[LTTNG_UUID_STR_LEN];
+
+               lttng_uuid_to_str(conn->session->sessiond_uuid, uuid_str);
+               ERR("Failed to find chunk to close: sessiond_uuid = %s, session_id = %" PRIu64 ", chunk_id = %" PRIu64,
+                               uuid_str,
+                               conn->session->id,
+                               msg->chunk_id);
                ret = -1;
-               goto end_no_reply;
+               reply_code = LTTNG_ERR_NOMEM;
+               goto end;
        }
 
-       /* Ensure the paths don't exceed their allowed size. */
-       ret = validate_rotate_rename_path_length("old", header.old_path_length);
-       if (ret) {
-               goto end;
+       pthread_mutex_lock(&session->lock);
+       if (close_command.is_set &&
+                       close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE) {
+               /*
+                * Clear command. It is a protocol error to ask for a
+                * clear on a relay which does not allow it. Querying
+                * the configuration allows figuring out whether
+                * clearing is allowed before doing the clear.
+                */
+               if (!opt_allow_clear) {
+                       ret = -1;
+                       reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+                       goto end_unlock_session;
+               }
        }
-       ret = validate_rotate_rename_path_length("new", header.new_path_length);
-       if (ret) {
-               goto end;
+       if (session->pending_closure_trace_chunk &&
+                       session->pending_closure_trace_chunk != chunk) {
+               ERR("Trace chunk close command for session \"%s\" does not target the trace chunk pending closure",
+                               session->session_name);
+               reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+               ret = -1;
+               goto end_unlock_session;
        }
 
-       old_path_view = lttng_buffer_view_from_view(payload, header_len,
-                       header.old_path_length);
-       new_path_view = lttng_buffer_view_from_view(payload,
-                       header_len + header.old_path_length,
-                       header.new_path_length);
+       if (session->current_trace_chunk && session->current_trace_chunk != chunk &&
+                       !lttng_trace_chunk_get_name_overridden(session->current_trace_chunk)) {
+               if (close_command.is_set &&
+                               close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_DELETE &&
+                               !session->has_rotated) {
+                       /* New chunk stays in session output directory. */
+                       new_path = "";
+               } else {
+                       /* Use chunk name for new chunk. */
+                       new_path = NULL;
+               }
+               /* Rename new chunk path. */
+               chunk_status = lttng_trace_chunk_rename_path(session->current_trace_chunk,
+                               new_path);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret = -1;
+                       goto end_unlock_session;
+               }
+               session->ongoing_rotation = false;
+       }
+       if ((!close_command.is_set ||
+                       close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_NO_OPERATION) &&
+                       !lttng_trace_chunk_get_name_overridden(chunk)) {
+               const char *old_path;
 
-       /* Validate that both paths received are NULL terminated. */
-       if (old_path_view.data[old_path_view.size - 1] != '\0') {
-               ERR("relay_rotate_rename command's \"old\" path is invalid (not NULL terminated)");
-               ret = -1;
-               goto end;
+               if (!session->has_rotated) {
+                       old_path = "";
+               } else {
+                       old_path = NULL;
+               }
+               /* We need to move back the .tmp_old_chunk to its rightful place. */
+               chunk_status = lttng_trace_chunk_rename_path(chunk, old_path);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret = -1;
+                       goto end_unlock_session;
+               }
        }
-       if (new_path_view.data[new_path_view.size - 1] != '\0') {
-               ERR("relay_rotate_rename command's \"new\" path is invalid (not NULL terminated)");
+       chunk_status = lttng_trace_chunk_set_close_timestamp(
+                       chunk, close_timestamp);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               ERR("Failed to set trace chunk close timestamp");
                ret = -1;
-               goto end;
+               reply_code = LTTNG_ERR_UNK;
+               goto end_unlock_session;
        }
 
-       complete_old_path = create_output_path(old_path_view.data);
-       if (!complete_old_path) {
-               ERR("Failed to build old output path in rotate_rename command");
+       if (close_command.is_set) {
+               chunk_status = lttng_trace_chunk_set_close_command(
+                               chunk, close_command.value);
+               if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+                       ret = -1;
+                       reply_code = LTTNG_ERR_INVALID;
+                       goto end_unlock_session;
+               }
+       }
+       chunk_status = lttng_trace_chunk_get_name(chunk, &chunk_name, NULL);
+       if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+               ERR("Failed to get chunk name");
                ret = -1;
-               goto end;
+               reply_code = LTTNG_ERR_UNK;
+               goto end_unlock_session;
        }
-
-       complete_new_path = create_output_path(new_path_view.data);
-       if (!complete_new_path) {
-               ERR("Failed to build new output path in rotate_rename command");
+       if (!session->has_rotated && !session->snapshot) {
+               ret = lttng_strncpy(closed_trace_chunk_path,
+                               session->output_path,
+                               sizeof(closed_trace_chunk_path));
+               if (ret) {
+                       ERR("Failed to send trace chunk path: path length of %zu bytes exceeds the maximal allowed length of %zu bytes",
+                                       strlen(session->output_path),
+                                       sizeof(closed_trace_chunk_path));
+                       reply_code = LTTNG_ERR_NOMEM;
+                       ret = -1;
+                       goto end_unlock_session;
+               }
+       } else {
+               if (session->snapshot) {
+                       ret = snprintf(closed_trace_chunk_path,
+                                       sizeof(closed_trace_chunk_path),
+                                       "%s/%s", session->output_path,
+                                       chunk_name);
+               } else {
+                       ret = snprintf(closed_trace_chunk_path,
+                                       sizeof(closed_trace_chunk_path),
+                                       "%s/" DEFAULT_ARCHIVED_TRACE_CHUNKS_DIRECTORY
+                                       "/%s",
+                                       session->output_path, chunk_name);
+               }
+               if (ret < 0 || ret == sizeof(closed_trace_chunk_path)) {
+                       ERR("Failed to format closed trace chunk resulting path");
+                       reply_code = ret < 0 ? LTTNG_ERR_UNK : LTTNG_ERR_NOMEM;
+                       ret = -1;
+                       goto end_unlock_session;
+               }
+       }
+       if (close_command.is_set &&
+                       close_command.value == LTTNG_TRACE_CHUNK_COMMAND_TYPE_MOVE_TO_COMPLETED) {
+               session->has_rotated = true;
+       }
+       DBG("Reply chunk path on close: %s", closed_trace_chunk_path);
+       path_length = strlen(closed_trace_chunk_path) + 1;
+       if (path_length > UINT32_MAX) {
+               ERR("Closed trace chunk path exceeds the maximal length allowed by the protocol");
                ret = -1;
-               goto end;
+               reply_code = LTTNG_ERR_INVALID_PROTOCOL;
+               goto end_unlock_session;
        }
 
-       ret = utils_mkdir_recursive(complete_new_path, S_IRWXU | S_IRWXG,
-                       -1, -1);
-       if (ret < 0) {
-               ERR("Failed to mkdir() rotate_rename's \"new\" output directory at \"%s\"",
-                               complete_new_path);
-               goto end;
+       if (session->current_trace_chunk == chunk) {
+               /*
+                * After a trace chunk close command, no new streams
+                * referencing the chunk may be created. Hence, on the
+                * event that no new trace chunk have been created for
+                * the session, the reference to the current trace chunk
+                * is released in order to allow it to be reclaimed when
+                * the last stream releases its reference to it.
+                */
+               lttng_trace_chunk_put(session->current_trace_chunk);
+               session->current_trace_chunk = NULL;
        }
+       lttng_trace_chunk_put(session->pending_closure_trace_chunk);
+       session->pending_closure_trace_chunk = NULL;
+end_unlock_session:
+       pthread_mutex_unlock(&session->lock);
 
-       /*
-        * If a domain has not yet created its channel, the domain-specific
-        * folder might not exist, but this is not an error.
-        */
-       ret = rename(complete_old_path, complete_new_path);
-       if (ret < 0 && errno != ENOENT) {
-               PERROR("Renaming chunk in rotate_rename command from \"%s\" to \"%s\"",
-                               complete_old_path, complete_new_path);
-               goto end;
+end:
+       reply.generic.ret_code = htobe32((uint32_t) reply_code);
+       reply.path_length = htobe32((uint32_t) path_length);
+       buf_ret = lttng_dynamic_buffer_append(
+                       &reply_payload, &reply, sizeof(reply));
+       if (buf_ret) {
+               ERR("Failed to append \"close trace chunk\" command reply header to payload buffer");
+               goto end_no_reply;
        }
-       ret = 0;
 
-end:
-       memset(&reply, 0, sizeof(reply));
-       if (ret < 0) {
-               reply.ret_code = htobe32(LTTNG_ERR_UNK);
-       } else {
-               reply.ret_code = htobe32(LTTNG_OK);
+       if (reply_code == LTTNG_OK) {
+               buf_ret = lttng_dynamic_buffer_append(&reply_payload,
+                               closed_trace_chunk_path, path_length);
+               if (buf_ret) {
+                       ERR("Failed to append \"close trace chunk\" command reply path to payload buffer");
+                       goto end_no_reply;
+               }
        }
-       send_ret = conn->sock->ops->sendmsg(conn->sock, &reply,
-                       sizeof(reply), 0);
-       if (send_ret < sizeof(reply)) {
-               ERR("Failed to send \"rotate rename\" command reply (ret = %zd)",
-                               send_ret);
+
+       send_ret = conn->sock->ops->sendmsg(conn->sock,
+                       reply_payload.data,
+                       reply_payload.size,
+                       0);
+       if (send_ret < reply_payload.size) {
+               ERR("Failed to send \"close trace chunk\" command reply of %zu bytes (ret = %zd)",
+                               reply_payload.size, send_ret);
                ret = -1;
+               goto end_no_reply;
        }
-
 end_no_reply:
-       free(complete_old_path);
-       free(complete_new_path);
+       lttng_trace_chunk_put(chunk);
+       lttng_dynamic_buffer_reset(&reply_payload);
        return ret;
 }
 
 /*
- * Check if all the streams in the session have completed the last rotation.
- * The chunk_id value is used to distinguish the cases where a stream was
- * closed on the consumerd before the rotation started but it still active on
- * the relayd, and the case where a stream appeared on the consumerd/relayd
- * after the last rotation started (in that case, it is already writing in the
- * new chunk folder).
+ * relay_trace_chunk_exists: check if a trace chunk exists
  */
-static
-int relay_rotate_pending(const struct lttcomm_relayd_hdr *recv_hdr,
+static int relay_trace_chunk_exists(const struct lttcomm_relayd_hdr *recv_hdr,
                struct relay_connection *conn,
                const struct lttng_buffer_view *payload)
 {
-       struct relay_session *session = conn->session;
-       struct lttcomm_relayd_rotate_pending msg;
-       struct lttcomm_relayd_rotate_pending_reply reply;
-       struct lttng_ht_iter iter;
-       struct relay_stream *stream;
        int ret = 0;
        ssize_t send_ret;
+       struct relay_session *session = conn->session;
+       struct lttcomm_relayd_trace_chunk_exists *msg;
+       struct lttcomm_relayd_trace_chunk_exists_reply reply = {};
+       struct lttng_buffer_view header_view;
        uint64_t chunk_id;
-        bool rotate_pending = false;
-
-       DBG("Rotate pending command received");
+       bool chunk_exists;
 
        if (!session || !conn->version_check_done) {
-               ERR("Trying to check for data before version check");
+               ERR("Trying to check for the existance of a trace chunk before version check");
                ret = -1;
                goto end_no_reply;
        }
 
        if (session->major == 2 && session->minor < 11) {
-               ERR("Unsupported feature before 2.11");
+               ERR("Chunk exists command is unsupported before 2.11");
                ret = -1;
                goto end_no_reply;
        }
 
-       if (payload->size < sizeof(msg)) {
-               ERR("Unexpected payload size in \"relay_rotate_pending\": expected >= %zu bytes, got %zu bytes",
-                               sizeof(msg), payload->size);
+       header_view = lttng_buffer_view_from_view(payload, 0, sizeof(*msg));
+       if (!header_view.data) {
+               ERR("Failed to receive payload of chunk exists command");
                ret = -1;
                goto end_no_reply;
        }
 
-       memcpy(&msg, payload->data, sizeof(msg));
-
-       chunk_id = be64toh(msg.chunk_id);
-
-       DBG("Evaluating rotate pending for chunk id %" PRIu64, chunk_id);
+       /* Convert to host endianness. */
+       msg = (typeof(msg)) header_view.data;
+       chunk_id = be64toh(msg->chunk_id);
 
+       ret = sessiond_trace_chunk_registry_chunk_exists(
+                       sessiond_trace_chunk_registry,
+                       conn->session->sessiond_uuid,
+                       conn->session->id,
+                       chunk_id, &chunk_exists);
        /*
-        * Iterate over all the streams in the session and check if they are
-        * still waiting for data to perform their rotation.
+        * If ret is not 0, send the reply and report the error to the caller.
+        * It is a protocol (or internal) error and the session/connection
+        * should be torn down.
         */
-       rcu_read_lock();
-       cds_lfht_for_each_entry(relay_streams_ht->ht, &iter.iter, stream,
-                       node.node) {
-               if (!stream_get(stream)) {
-                       continue;
-               }
-               if (stream->trace->session != session) {
-                       stream_put(stream);
-                       continue;
-               }
-               pthread_mutex_lock(&stream->lock);
-               if (stream->rotate_at_seq_num != -1ULL) {
-                       /* We have not yet performed the rotation. */
-                       rotate_pending = true;
-                       DBG("Stream %" PRIu64 " is still rotating",
-                                       stream->stream_handle);
-               } else if (stream->chunk_id < chunk_id) {
-                       /*
-                        * Stream closed on the consumer but still active on the
-                        * relay.
-                        */
-                       rotate_pending = true;
-                       DBG("Stream %" PRIu64 " did not exist on the consumer "
-                                       "when the last rotation started, but is"
-                                       "still waiting for data before getting"
-                                       "closed",
-                                       stream->stream_handle);
-               }
-               pthread_mutex_unlock(&stream->lock);
-               stream_put(stream);
-               if (rotate_pending) {
-                       goto send_reply;
-               }
+       reply = (typeof(reply)){
+               .generic.ret_code = htobe32((uint32_t)
+                       (ret == 0 ? LTTNG_OK : LTTNG_ERR_INVALID_PROTOCOL)),
+               .trace_chunk_exists = ret == 0 ? chunk_exists : 0,
+       };
+       send_ret = conn->sock->ops->sendmsg(
+                       conn->sock, &reply, sizeof(reply), 0);
+       if (send_ret < (ssize_t) sizeof(reply)) {
+               ERR("Failed to send \"create trace chunk\" command reply (ret = %zd)",
+                               send_ret);
+               ret = -1;
        }
+end_no_reply:
+       return ret;
+}
 
-send_reply:
-       rcu_read_unlock();
-       memset(&reply, 0, sizeof(reply));
-       reply.generic.ret_code = htobe32((uint32_t) LTTNG_OK);
-       reply.is_pending = (uint8_t) !!rotate_pending;
-       send_ret = conn->sock->ops->sendmsg(conn->sock, &reply,
-                       sizeof(reply), 0);
+/*
+ * relay_get_configuration: query whether feature is available
+ */
+static int relay_get_configuration(const struct lttcomm_relayd_hdr *recv_hdr,
+               struct relay_connection *conn,
+               const struct lttng_buffer_view *payload)
+{
+       int ret = 0;
+       ssize_t send_ret;
+       struct lttcomm_relayd_get_configuration *msg;
+       struct lttcomm_relayd_get_configuration_reply reply = {};
+       struct lttng_buffer_view header_view;
+       uint64_t query_flags = 0;
+       uint64_t result_flags = 0;
+
+       header_view = lttng_buffer_view_from_view(payload, 0, sizeof(*msg));
+       if (!header_view.data) {
+               ERR("Failed to receive payload of chunk close command");
+               ret = -1;
+               goto end_no_reply;
+       }
+
+       /* Convert to host endianness. */
+       msg = (typeof(msg)) header_view.data;
+       query_flags = be64toh(msg->query_flags);
+
+       if (query_flags) {
+               ret = LTTNG_ERR_INVALID_PROTOCOL;
+               goto reply;
+       }
+       if (opt_allow_clear) {
+               result_flags |= LTTCOMM_RELAYD_CONFIGURATION_FLAG_CLEAR_ALLOWED;
+       }
+       ret = 0;
+reply:
+       reply = (typeof(reply)){
+               .generic.ret_code = htobe32((uint32_t)
+                       (ret == 0 ? LTTNG_OK : LTTNG_ERR_INVALID_PROTOCOL)),
+               .relayd_configuration_flags = htobe64(result_flags),
+       };
+       send_ret = conn->sock->ops->sendmsg(
+                       conn->sock, &reply, sizeof(reply), 0);
        if (send_ret < (ssize_t) sizeof(reply)) {
-               ERR("Failed to send \"rotate pending\" command reply (ret = %zd)",
+               ERR("Failed to send \"get configuration\" command reply (ret = %zd)",
                                send_ret);
                ret = -1;
        }
-
 end_no_reply:
        return ret;
 }
@@ -2917,21 +3266,25 @@ static int relay_process_control_command(struct relay_connection *conn,
                DBG_CMD("RELAYD_RESET_METADATA", conn);
                ret = relay_reset_metadata(header, conn, payload);
                break;
-       case RELAYD_ROTATE_STREAM:
-               DBG_CMD("RELAYD_ROTATE_STREAM", conn);
-               ret = relay_rotate_session_stream(header, conn, payload);
+       case RELAYD_ROTATE_STREAMS:
+               DBG_CMD("RELAYD_ROTATE_STREAMS", conn);
+               ret = relay_rotate_session_streams(header, conn, payload);
+               break;
+       case RELAYD_CREATE_TRACE_CHUNK:
+               DBG_CMD("RELAYD_CREATE_TRACE_CHUNK", conn);
+               ret = relay_create_trace_chunk(header, conn, payload);
                break;
-       case RELAYD_ROTATE_RENAME:
-               DBG_CMD("RELAYD_ROTATE_RENAME", conn);
-               ret = relay_rotate_rename(header, conn, payload);
+       case RELAYD_CLOSE_TRACE_CHUNK:
+               DBG_CMD("RELAYD_CLOSE_TRACE_CHUNK", conn);
+               ret = relay_close_trace_chunk(header, conn, payload);
                break;
-       case RELAYD_ROTATE_PENDING:
-               DBG_CMD("RELAYD_ROTATE_PENDING", conn);
-               ret = relay_rotate_pending(header, conn, payload);
+       case RELAYD_TRACE_CHUNK_EXISTS:
+               DBG_CMD("RELAYD_TRACE_CHUNK_EXISTS", conn);
+               ret = relay_trace_chunk_exists(header, conn, payload);
                break;
-       case RELAYD_MKDIR:
-               DBG_CMD("RELAYD_MKDIR", conn);
-               ret = relay_mkdir(header, conn, payload);
+       case RELAYD_GET_CONFIGURATION:
+               DBG_CMD("RELAYD_GET_CONFIGURATION", conn);
+               ret = relay_get_configuration(header, conn, payload);
                break;
        case RELAYD_UPDATE_SYNC_INFO:
        default:
@@ -2945,9 +3298,11 @@ end:
        return ret;
 }
 
-static int relay_process_control_receive_payload(struct relay_connection *conn)
+static enum relay_connection_status relay_process_control_receive_payload(
+               struct relay_connection *conn)
 {
        int ret = 0;
+       enum relay_connection_status status = RELAY_CONNECTION_STATUS_OK;
        struct lttng_dynamic_buffer *reception_buffer =
                        &conn->protocol.ctrl.reception_buffer;
        struct ctrl_connection_state_receive_payload *state =
@@ -2963,11 +3318,15 @@ static int relay_process_control_receive_payload(struct relay_connection *conn)
                        reception_buffer->data + state->received,
                        state->left_to_receive, MSG_DONTWAIT);
        if (ret < 0) {
-               ERR("Unable to receive command payload on sock %d", conn->sock->fd);
+               if (errno != EAGAIN && errno != EWOULDBLOCK) {
+                       PERROR("Unable to receive command payload on sock %d",
+                                       conn->sock->fd);
+                       status = RELAY_CONNECTION_STATUS_ERROR;
+               }
                goto end;
        } else if (ret == 0) {
                DBG("Socket %d performed an orderly shutdown (received EOF)", conn->sock->fd);
-               ret = -1;
+               status = RELAY_CONNECTION_STATUS_CLOSED;
                goto end;
        }
 
@@ -2985,7 +3344,6 @@ static int relay_process_control_receive_payload(struct relay_connection *conn)
                DBG3("Partial reception of control connection protocol payload (received %" PRIu64 " bytes, %" PRIu64 " bytes left to receive, fd = %i)",
                                state->received, state->left_to_receive,
                                conn->sock->fd);
-               ret = 0;
                goto end;
        }
 
@@ -3004,17 +3362,23 @@ reception_complete:
        ret = relay_process_control_command(conn,
                        &state->header, &payload_view);
        if (ret < 0) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end;
        }
 
        ret = connection_reset_protocol_state(conn);
+       if (ret) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
+       }
 end:
-       return ret;
+       return status;
 }
 
-static int relay_process_control_receive_header(struct relay_connection *conn)
+static enum relay_connection_status relay_process_control_receive_header(
+               struct relay_connection *conn)
 {
        int ret = 0;
+       enum relay_connection_status status = RELAY_CONNECTION_STATUS_OK;
        struct lttcomm_relayd_hdr header;
        struct lttng_dynamic_buffer *reception_buffer =
                        &conn->protocol.ctrl.reception_buffer;
@@ -3027,11 +3391,15 @@ static int relay_process_control_receive_header(struct relay_connection *conn)
                        reception_buffer->data + state->received,
                        state->left_to_receive, MSG_DONTWAIT);
        if (ret < 0) {
-               ERR("Unable to receive control command header on sock %d", conn->sock->fd);
+               if (errno != EAGAIN && errno != EWOULDBLOCK) {
+                       PERROR("Unable to receive control command header on sock %d",
+                                       conn->sock->fd);
+                       status = RELAY_CONNECTION_STATUS_ERROR;
+               }
                goto end;
        } else if (ret == 0) {
                DBG("Socket %d performed an orderly shutdown (received EOF)", conn->sock->fd);
-               ret = -1;
+               status = RELAY_CONNECTION_STATUS_CLOSED;
                goto end;
        }
 
@@ -3049,7 +3417,6 @@ static int relay_process_control_receive_header(struct relay_connection *conn)
                DBG3("Partial reception of control connection protocol header (received %" PRIu64 " bytes, %" PRIu64 " bytes left to receive, fd = %i)",
                                state->received, state->left_to_receive,
                                conn->sock->fd);
-               ret = 0;
                goto end;
        }
 
@@ -3068,11 +3435,10 @@ static int relay_process_control_receive_header(struct relay_connection *conn)
                        conn->sock->fd, header.cmd, header.cmd_version,
                        header.data_size);
 
-       /* FIXME temporary arbitrary limit on data size. */
-       if (header.data_size > (128 * 1024 * 1024)) {
+       if (header.data_size > DEFAULT_NETWORK_RELAYD_CTRL_MAX_PAYLOAD_SIZE) {
                ERR("Command header indicates a payload (%" PRIu64 " bytes) that exceeds the maximal payload size allowed on a control connection.",
                                header.data_size);
-               ret = -1;
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end;
        }
 
@@ -3082,6 +3448,7 @@ static int relay_process_control_receive_header(struct relay_connection *conn)
        ret = lttng_dynamic_buffer_set_size(reception_buffer,
                        header.data_size);
        if (ret) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end;
        }
 
@@ -3090,106 +3457,40 @@ static int relay_process_control_receive_header(struct relay_connection *conn)
                 * Manually invoke the next state as the poll loop
                 * will not wake-up to allow us to proceed further.
                 */
-               ret = relay_process_control_receive_payload(conn);
+               status = relay_process_control_receive_payload(conn);
        }
 end:
-       return ret;
+       return status;
 }
 
 /*
  * Process the commands received on the control socket
  */
-static int relay_process_control(struct relay_connection *conn)
+static enum relay_connection_status relay_process_control(
+               struct relay_connection *conn)
 {
-       int ret = 0;
+       enum relay_connection_status status;
 
        switch (conn->protocol.ctrl.state_id) {
        case CTRL_CONNECTION_STATE_RECEIVE_HEADER:
-               ret = relay_process_control_receive_header(conn);
+               status = relay_process_control_receive_header(conn);
                break;
        case CTRL_CONNECTION_STATE_RECEIVE_PAYLOAD:
-               ret = relay_process_control_receive_payload(conn);
+               status = relay_process_control_receive_payload(conn);
                break;
        default:
                ERR("Unknown control connection protocol state encountered.");
                abort();
        }
 
-       return ret;
-}
-
-/*
- * Handle index for a data stream.
- *
- * Called with the stream lock held.
- *
- * Return 0 on success else a negative value.
- */
-static int handle_index_data(struct relay_stream *stream, uint64_t net_seq_num,
-               bool rotate_index, bool *flushed, uint64_t total_size)
-{
-       int ret = 0;
-       uint64_t data_offset;
-       struct relay_index *index;
-
-       /* Get data offset because we are about to update the index. */
-       data_offset = htobe64(stream->tracefile_size_current);
-
-       DBG("handle_index_data: stream %" PRIu64 " net_seq_num %" PRIu64 " data offset %" PRIu64,
-                       stream->stream_handle, net_seq_num, stream->tracefile_size_current);
-
-       /*
-        * Lookup for an existing index for that stream id/sequence
-        * number. If it exists, the control thread has already received the
-        * data for it, thus we need to write it to disk.
-        */
-       index = relay_index_get_by_id_or_create(stream, net_seq_num);
-       if (!index) {
-               ret = -1;
-               goto end;
-       }
-
-       if (rotate_index || !stream->index_file) {
-               ret = create_rotate_index_file(stream);
-               if (ret < 0) {
-                       ERR("Failed to rotate index");
-                       /* Put self-ref for this index due to error. */
-                       relay_index_put(index);
-                       index = NULL;
-                       goto end;
-               }
-       }
-
-       if (relay_index_set_file(index, stream->index_file, data_offset)) {
-               ret = -1;
-               /* Put self-ref for this index due to error. */
-               relay_index_put(index);
-               index = NULL;
-               goto end;
-       }
-
-       ret = relay_index_try_flush(index);
-       if (ret == 0) {
-               tracefile_array_commit_seq(stream->tfa);
-               stream->index_received_seqcount++;
-               *flushed = true;
-       } else if (ret > 0) {
-               index->total_size = total_size;
-               /* No flush. */
-               ret = 0;
-       } else {
-               /* Put self-ref for this index due to error. */
-               relay_index_put(index);
-               index = NULL;
-               ret = -1;
-       }
-end:
-       return ret;
+       return status;
 }
 
-static int relay_process_data_receive_header(struct relay_connection *conn)
+static enum relay_connection_status relay_process_data_receive_header(
+               struct relay_connection *conn)
 {
        int ret;
+       enum relay_connection_status status = RELAY_CONNECTION_STATUS_OK;
        struct data_connection_state_receive_header *state =
                        &conn->protocol.data.state.receive_header;
        struct lttcomm_relayd_data_hdr header;
@@ -3201,12 +3502,15 @@ static int relay_process_data_receive_header(struct relay_connection *conn)
                        state->header_reception_buffer + state->received,
                        state->left_to_receive, MSG_DONTWAIT);
        if (ret < 0) {
-               ERR("Unable to receive data header on sock %d", conn->sock->fd);
+               if (errno != EAGAIN && errno != EWOULDBLOCK) {
+                       PERROR("Unable to receive data header on sock %d", conn->sock->fd);
+                       status = RELAY_CONNECTION_STATUS_ERROR;
+               }
                goto end;
        } else if (ret == 0) {
                /* Orderly shutdown. Not necessary to print an error. */
                DBG("Socket %d performed an orderly shutdown (received EOF)", conn->sock->fd);
-               ret = -1;
+               status = RELAY_CONNECTION_STATUS_CLOSED;
                goto end;
        }
 
@@ -3224,7 +3528,6 @@ static int relay_process_data_receive_header(struct relay_connection *conn)
                DBG3("Partial reception of data connection header (received %" PRIu64 " bytes, %" PRIu64 " bytes left to receive, fd = %i)",
                                state->received, state->left_to_receive,
                                conn->sock->fd);
-               ret = 0;
                goto end;
        }
 
@@ -3253,53 +3556,33 @@ static int relay_process_data_receive_header(struct relay_connection *conn)
        if (!stream) {
                DBG("relay_process_data_receive_payload: Cannot find stream %" PRIu64,
                                header.stream_id);
-               ret = 0;
+               /* Protocol error. */
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end;
        }
 
        pthread_mutex_lock(&stream->lock);
-
-       /* Check if a rotation is needed. */
-       if (stream->tracefile_size > 0 &&
-                       (stream->tracefile_size_current + header.data_size) >
-                       stream->tracefile_size) {
-               uint64_t old_id, new_id;
-
-               old_id = tracefile_array_get_file_index_head(stream->tfa);
-               tracefile_array_file_rotate(stream->tfa);
-
-               /* new_id is updated by utils_rotate_stream_file. */
-               new_id = old_id;
-
-               ret = utils_rotate_stream_file(stream->path_name,
-                               stream->channel_name, stream->tracefile_size,
-                               stream->tracefile_count, -1,
-                               -1, stream->stream_fd->fd,
-                               &new_id, &stream->stream_fd->fd);
-               if (ret < 0) {
-                       ERR("Failed to rotate stream output file");
-                       goto end_stream_unlock;
-               }
-
-               /*
-                * Reset current size because we just performed a stream
-                * rotation.
-                */
-               stream->tracefile_size_current = 0;
-               conn->protocol.data.state.receive_payload.rotate_index = true;
+       /* Prepare stream for the reception of a new packet. */
+       ret = stream_init_packet(stream, header.data_size,
+                       &conn->protocol.data.state.receive_payload.rotate_index);
+       pthread_mutex_unlock(&stream->lock);
+       if (ret) {
+               ERR("Failed to rotate stream output file");
+               status = RELAY_CONNECTION_STATUS_ERROR;
+               goto end_stream_unlock;
        }
 
-       ret = 0;
 end_stream_unlock:
-       pthread_mutex_unlock(&stream->lock);
        stream_put(stream);
 end:
-       return ret;
+       return status;
 }
 
-static int relay_process_data_receive_payload(struct relay_connection *conn)
+static enum relay_connection_status relay_process_data_receive_payload(
+               struct relay_connection *conn)
 {
        int ret;
+       enum relay_connection_status status = RELAY_CONNECTION_STATUS_OK;
        struct relay_stream *stream;
        struct data_connection_state_receive_payload *state =
                        &conn->protocol.data.state.receive_payload;
@@ -3310,20 +3593,28 @@ static int relay_process_data_receive_payload(struct relay_connection *conn)
        uint64_t left_to_receive = state->left_to_receive;
        struct relay_session *session;
 
+       DBG3("Receiving data for stream id %" PRIu64 " seqnum %" PRIu64 ", %" PRIu64" bytes received, %" PRIu64 " bytes left to receive",
+                       state->header.stream_id, state->header.net_seq_num,
+                       state->received, left_to_receive);
+
        stream = stream_get_by_id(state->header.stream_id);
        if (!stream) {
-               DBG("relay_process_data_receive_payload: Cannot find stream %" PRIu64,
+               /* Protocol error. */
+               ERR("relay_process_data_receive_payload: cannot find stream %" PRIu64,
                                state->header.stream_id);
-               ret = 0;
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end;
        }
 
        pthread_mutex_lock(&stream->lock);
        session = stream->trace->session;
-
-       DBG3("Receiving data for stream id %" PRIu64 " seqnum %" PRIu64 ", %" PRIu64" bytes received, %" PRIu64 " bytes left to receive",
-                       state->header.stream_id, state->header.net_seq_num,
-                       state->received, left_to_receive);
+       if (!conn->session) {
+               ret = connection_set_session(conn, session);
+               if (ret) {
+                       status = RELAY_CONNECTION_STATUS_ERROR;
+                       goto end_stream_unlock;
+               }
+       }
 
        /*
         * The size of the "chunk" received on any iteration is bounded by:
@@ -3332,19 +3623,22 @@ static int relay_process_data_receive_payload(struct relay_connection *conn)
         *   - the on-stack data buffer
         */
        while (left_to_receive > 0 && !partial_recv) {
-               ssize_t write_ret;
                size_t recv_size = min(left_to_receive, chunk_size);
+               struct lttng_buffer_view packet_chunk;
 
                ret = conn->sock->ops->recvmsg(conn->sock, data_buffer,
                                recv_size, MSG_DONTWAIT);
                if (ret < 0) {
-                       ERR("Socket %d error %d", conn->sock->fd, ret);
-                       ret = -1;
+                       if (errno != EAGAIN && errno != EWOULDBLOCK) {
+                               PERROR("Socket %d error", conn->sock->fd);
+                               status = RELAY_CONNECTION_STATUS_ERROR;
+                       }
                        goto end_stream_unlock;
                } else if (ret == 0) {
                        /* No more data ready to be consumed on socket. */
                        DBG3("No more data ready for consumption on data socket of stream id %" PRIu64,
                                        state->header.stream_id);
+                       status = RELAY_CONNECTION_STATUS_CLOSED;
                        break;
                } else if (ret < (int) recv_size) {
                        /*
@@ -3352,25 +3646,23 @@ static int relay_process_data_receive_payload(struct relay_connection *conn)
                         * consumed.
                         */
                        partial_recv = true;
+                       recv_size = ret;
                }
 
-               recv_size = ret;
+               packet_chunk = lttng_buffer_view_init(data_buffer,
+                               0, recv_size);
+               assert(packet_chunk.data);
 
-               /* Write data to stream output fd. */
-               write_ret = lttng_write(stream->stream_fd->fd, data_buffer,
-                               recv_size);
-               if (write_ret < (ssize_t) recv_size) {
+               ret = stream_write(stream, &packet_chunk, 0);
+               if (ret) {
                        ERR("Relay error writing data to file");
-                       ret = -1;
+                       status = RELAY_CONNECTION_STATUS_ERROR;
                        goto end_stream_unlock;
                }
 
                left_to_receive -= recv_size;
                state->received += recv_size;
                state->left_to_receive = left_to_receive;
-
-               DBG2("Relay wrote %zd bytes to tracefile for stream id %" PRIu64,
-                               write_ret, stream->stream_handle);
        }
 
        if (state->left_to_receive > 0) {
@@ -3381,43 +3673,39 @@ static int relay_process_data_receive_payload(struct relay_connection *conn)
                DBG3("Partial receive on data connection of stream id %" PRIu64 ", %" PRIu64 " bytes received, %" PRIu64 " bytes left to receive",
                                state->header.stream_id, state->received,
                                state->left_to_receive);
-               ret = 0;
                goto end_stream_unlock;
        }
 
-       ret = write_padding_to_file(stream->stream_fd->fd,
-                       state->header.padding_size);
-       if (ret < 0) {
-               ERR("write_padding_to_file: fail stream %" PRIu64 " net_seq_num %" PRIu64 " ret %d",
-                               stream->stream_handle,
-                               state->header.net_seq_num, ret);
+       ret = stream_write(stream, NULL, state->header.padding_size);
+       if (ret) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
                goto end_stream_unlock;
        }
 
-
-       if (session->minor >= 4 && !session->snapshot) {
-               ret = handle_index_data(stream, state->header.net_seq_num,
-                               state->rotate_index, &index_flushed, state->header.data_size + state->header.padding_size);
+       if (session_streams_have_index(session)) {
+               ret = stream_update_index(stream, state->header.net_seq_num,
+                               state->rotate_index, &index_flushed,
+                               state->header.data_size + state->header.padding_size);
                if (ret < 0) {
-                       ERR("handle_index_data: fail stream %" PRIu64 " net_seq_num %" PRIu64 " ret %d",
+                       ERR("Failed to update index: stream %" PRIu64 " net_seq_num %" PRIu64 " ret %d",
                                        stream->stream_handle,
                                        state->header.net_seq_num, ret);
+                       status = RELAY_CONNECTION_STATUS_ERROR;
                        goto end_stream_unlock;
                }
        }
 
-       stream->tracefile_size_current += state->header.data_size +
-                       state->header.padding_size;
-
-       if (stream->prev_seq == -1ULL) {
+       if (stream->prev_data_seq == -1ULL) {
                new_stream = true;
        }
-       if (index_flushed) {
-               stream->pos_after_last_complete_data_index =
-                               stream->tracefile_size_current;
-       }
 
-       stream->prev_seq = state->header.net_seq_num;
+       ret = stream_complete_packet(stream, state->header.data_size +
+                       state->header.padding_size, state->header.net_seq_num,
+                       index_flushed);
+       if (ret) {
+               status = RELAY_CONNECTION_STATUS_ERROR;
+               goto end_stream_unlock;
+       }
 
        /*
         * Resetting the protocol state (to RECEIVE_HEADER) will trash the
@@ -3427,11 +3715,6 @@ static int relay_process_data_receive_payload(struct relay_connection *conn)
        connection_reset_protocol_state(conn);
        state = NULL;
 
-       ret = try_rotate_stream(stream);
-       if (ret < 0) {
-               goto end_stream_unlock;
-       }
-
 end_stream_unlock:
        close_requested = stream->close_requested;
        pthread_mutex_unlock(&stream->lock);
@@ -3447,29 +3730,30 @@ end_stream_unlock:
 
        stream_put(stream);
 end:
-       return ret;
+       return status;
 }
 
 /*
  * relay_process_data: Process the data received on the data socket
  */
-static int relay_process_data(struct relay_connection *conn)
+static enum relay_connection_status relay_process_data(
+               struct relay_connection *conn)
 {
-       int ret;
+       enum relay_connection_status status;
 
        switch (conn->protocol.data.state_id) {
        case DATA_CONNECTION_STATE_RECEIVE_HEADER:
-               ret = relay_process_data_receive_header(conn);
+               status = relay_process_data_receive_header(conn);
                break;
        case DATA_CONNECTION_STATE_RECEIVE_PAYLOAD:
-               ret = relay_process_data_receive_payload(conn);
+               status = relay_process_data_receive_payload(conn);
                break;
        default:
                ERR("Unexpected data connection communication state.");
                abort();
        }
 
-       return ret;
+       return status;
 }
 
 static void cleanup_connection_pollfd(struct lttng_poll_event *events, int pollfd)
@@ -3478,7 +3762,8 @@ static void cleanup_connection_pollfd(struct lttng_poll_event *events, int pollf
 
        (void) lttng_poll_del(events, pollfd);
 
-       ret = close(pollfd);
+       ret = fd_tracker_close_unsuspendable_fd(the_fd_tracker, &pollfd, 1,
+                       fd_tracker_util_close_fd, NULL);
        if (ret < 0) {
                ERR("Closing pollfd %d", pollfd);
        }
@@ -3540,7 +3825,7 @@ static void *relay_thread_worker(void *data)
                goto relay_connections_ht_error;
        }
 
-       ret = create_thread_poll_set(&events, 2);
+       ret = create_named_thread_poll_set(&events, 2, "Worker thread epoll");
        if (ret < 0) {
                goto error_poll_create;
        }
@@ -3585,14 +3870,6 @@ restart:
 
                        health_code_update();
 
-                       if (!revents) {
-                               /*
-                                * No activity for this FD (poll
-                                * implementation).
-                                */
-                               continue;
-                       }
-
                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
@@ -3609,8 +3886,13 @@ restart:
                                        if (ret < 0) {
                                                goto error;
                                        }
-                                       lttng_poll_add(&events, conn->sock->fd,
+                                       ret = lttng_poll_add(&events,
+                                                       conn->sock->fd,
                                                        LPOLLIN | LPOLLRDHUP);
+                                       if (ret) {
+                                               ERR("Failed to add new connection file descriptor to poll set");
+                                               goto error;
+                                       }
                                        connection_ht_add(relay_connections_ht, conn);
                                        DBG("Connection socket %d added", conn->sock->fd);
                                } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
@@ -3641,9 +3923,31 @@ restart:
                                assert(ctrl_conn->type == RELAY_CONTROL);
 
                                if (revents & LPOLLIN) {
-                                       ret = relay_process_control(ctrl_conn);
-                                       if (ret < 0) {
-                                               /* Clear the connection on error. */
+                                       enum relay_connection_status status;
+
+                                       status = relay_process_control(ctrl_conn);
+                                       if (status != RELAY_CONNECTION_STATUS_OK) {
+                                               /*
+                                                * On socket error flag the session as aborted to force
+                                                * the cleanup of its stream otherwise it can leak
+                                                * during the lifetime of the relayd.
+                                                *
+                                                * This prevents situations in which streams can be
+                                                * left opened because an index was received, the
+                                                * control connection is closed, and the data
+                                                * connection is closed (uncleanly) before the packet's
+                                                * data provided.
+                                                *
+                                                * Since the control connection encountered an error,
+                                                * it is okay to be conservative and close the
+                                                * session right now as we can't rely on the protocol
+                                                * being respected anymore.
+                                                */
+                                               if (status == RELAY_CONNECTION_STATUS_ERROR) {
+                                                       session_abort(ctrl_conn->session);
+                                               }
+
+                                               /* Clear the connection on error or close. */
                                                relay_thread_close_connection(&events,
                                                                pollfd,
                                                                ctrl_conn);
@@ -3717,9 +4021,30 @@ restart:
                        assert(data_conn->type == RELAY_DATA);
 
                        if (revents & LPOLLIN) {
-                               ret = relay_process_data(data_conn);
-                               /* Connection closed */
-                               if (ret < 0) {
+                               enum relay_connection_status status;
+
+                               status = relay_process_data(data_conn);
+                               /* Connection closed or error. */
+                               if (status != RELAY_CONNECTION_STATUS_OK) {
+                                       /*
+                                        * On socket error flag the session as aborted to force
+                                        * the cleanup of its stream otherwise it can leak
+                                        * during the lifetime of the relayd.
+                                        *
+                                        * This prevents situations in which streams can be
+                                        * left opened because an index was received, the
+                                        * control connection is closed, and the data
+                                        * connection is closed (uncleanly) before the packet's
+                                        * data provided.
+                                        *
+                                        * Since the data connection encountered an error,
+                                        * it is okay to be conservative and close the
+                                        * session right now as we can't rely on the protocol
+                                        * being respected anymore.
+                                        */
+                                       if (status == RELAY_CONNECTION_STATUS_ERROR) {
+                                               session_abort(data_conn->session);
+                                       }
                                        relay_thread_close_connection(&events, pollfd,
                                                        data_conn);
                                        /*
@@ -3751,16 +4076,14 @@ restart:
 
 exit:
 error:
-       /* Cleanup reamaining connection object. */
+       /* Cleanup remaining connection object. */
        rcu_read_lock();
        cds_lfht_for_each_entry(relay_connections_ht->ht, &iter.iter,
                        destroy_conn,
                        sock_n.node) {
                health_code_update();
 
-               if (session_abort(destroy_conn->session)) {
-                       assert(0);
-               }
+               session_abort(destroy_conn->session);
 
                /*
                 * No need to grab another ref, because we own
@@ -3771,12 +4094,13 @@ error:
        }
        rcu_read_unlock();
 
-       lttng_poll_clean(&events);
+       (void) fd_tracker_util_poll_clean(the_fd_tracker, &events);
 error_poll_create:
        lttng_ht_destroy(relay_connections_ht);
 relay_connections_ht_error:
        /* Close relay conn pipes */
-       utils_close_pipe(relay_conn_pipe);
+       (void) fd_tracker_util_pipe_close(the_fd_tracker,
+                       relay_conn_pipe);
        if (err) {
                DBG("Thread exited with error");
        }
@@ -3798,11 +4122,24 @@ error_testpoint:
  */
 static int create_relay_conn_pipe(void)
 {
-       int ret;
+       return fd_tracker_util_pipe_open_cloexec(the_fd_tracker,
+                       "Relayd connection pipe", relay_conn_pipe);
+}
 
-       ret = utils_create_pipe_cloexec(relay_conn_pipe);
+static int stdio_open(void *data, int *fds)
+{
+       fds[0] = fileno(stdout);
+       fds[1] = fileno(stderr);
+       return 0;
+}
 
-       return ret;
+static int track_stdio(void)
+{
+       int fds[2];
+       const char *names[] = { "stdout", "stderr" };
+
+       return fd_tracker_open_unsuspendable_fd(the_fd_tracker, fds,
+                       names, 2, stdio_open, NULL);
 }
 
 /*
@@ -3810,10 +4147,22 @@ static int create_relay_conn_pipe(void)
  */
 int main(int argc, char **argv)
 {
+       bool thread_is_rcu_registered = false;
        int ret = 0, retval = 0;
        void *status;
+       char *unlinked_file_directory_path = NULL, *output_path = NULL;
+
+       /* Parse environment variables */
+       ret = parse_env_options();
+       if (ret) {
+               retval = -1;
+               goto exit_options;
+       }
 
-       /* Parse arguments */
+       /*
+        * Parse arguments.
+        * Command line arguments overwrite environment.
+        */
        progname = argv[0];
        if (set_options(argc, argv)) {
                retval = -1;
@@ -3825,6 +4174,22 @@ int main(int argc, char **argv)
                goto exit_options;
        }
 
+       relayd_config_log();
+
+       if (opt_print_version) {
+               print_version();
+               retval = 0;
+               goto exit_options;
+       }
+
+       ret = fclose(stdin);
+       if (ret) {
+               PERROR("Failed to close stdin");
+               goto exit_options;
+       }
+
+       DBG("Clear command %s", opt_allow_clear ? "allowed" : "disallowed");
+
        /* Try to create directory if -o, --output is specified. */
        if (opt_output_path) {
                if (*opt_output_path != '/') {
@@ -3844,43 +4209,84 @@ int main(int argc, char **argv)
 
        /* Daemonize */
        if (opt_daemon || opt_background) {
-               int i;
-
                ret = lttng_daemonize(&child_ppid, &recv_child_signal,
                        !opt_background);
                if (ret < 0) {
                        retval = -1;
                        goto exit_options;
                }
+       }
 
-               /*
-                * We are in the child. Make sure all other file
-                * descriptors are closed, in case we are called with
-                * more opened file descriptors than the standard ones.
-                */
-               for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
-                       (void) close(i);
+       if (opt_working_directory) {
+               ret = utils_change_working_directory(opt_working_directory);
+               if (ret) {
+                       /* All errors are already logged. */
+                       goto exit_options;
                }
        }
 
+       sessiond_trace_chunk_registry = sessiond_trace_chunk_registry_create();
+       if (!sessiond_trace_chunk_registry) {
+               ERR("Failed to initialize session daemon trace chunk registry");
+               retval = -1;
+               goto exit_options;
+       }
+
+       /*
+        * The RCU thread registration (and use, through the fd-tracker's
+        * creation) is done after the daemonization to allow us to not
+        * deal with liburcu's fork() management as the call RCU needs to
+        * be restored.
+        */
+       rcu_register_thread();
+       thread_is_rcu_registered = true;
+
+       output_path = create_output_path("");
+       if (!output_path) {
+               ERR("Failed to get output path");
+               retval = -1;
+               goto exit_options;
+       }
+       ret = asprintf(&unlinked_file_directory_path, "%s/%s", output_path,
+                       DEFAULT_UNLINKED_FILES_DIRECTORY);
+       free(output_path);
+       if (ret < 0) {
+               ERR("Failed to format unlinked file directory path");
+               retval = -1;
+               goto exit_options;
+       }
+       the_fd_tracker = fd_tracker_create(
+                       unlinked_file_directory_path, lttng_opt_fd_pool_size);
+       free(unlinked_file_directory_path);
+       if (!the_fd_tracker) {
+               retval = -1;
+               goto exit_options;
+       }
+
+       ret = track_stdio();
+       if (ret) {
+               retval = -1;
+               goto exit_options;
+       }
+
        /* Initialize thread health monitoring */
        health_relayd = health_app_create(NR_HEALTH_RELAYD_TYPES);
        if (!health_relayd) {
                PERROR("health_app_create error");
                retval = -1;
-               goto exit_health_app_create;
+               goto exit_options;
        }
 
        /* Create thread quit pipe */
        if (init_thread_quit_pipe()) {
                retval = -1;
-               goto exit_init_data;
+               goto exit_options;
        }
 
        /* Setup the thread apps communication pipe. */
        if (create_relay_conn_pipe()) {
                retval = -1;
-               goto exit_init_data;
+               goto exit_options;
        }
 
        /* Init relay command queue. */
@@ -3894,27 +4300,27 @@ int main(int argc, char **argv)
        sessions_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
        if (!sessions_ht) {
                retval = -1;
-               goto exit_init_data;
+               goto exit_options;
        }
 
        /* tables of streams indexed by stream ID */
        relay_streams_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
        if (!relay_streams_ht) {
                retval = -1;
-               goto exit_init_data;
+               goto exit_options;
        }
 
        /* tables of streams indexed by stream ID */
        viewer_streams_ht = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
        if (!viewer_streams_ht) {
                retval = -1;
-               goto exit_init_data;
+               goto exit_options;
        }
 
-       ret = utils_create_pipe(health_quit_pipe);
+       ret = init_health_quit_pipe();
        if (ret) {
                retval = -1;
-               goto exit_health_quit_pipe;
+               goto exit_options;
        }
 
        /* Create thread to manage the client socket */
@@ -3924,7 +4330,7 @@ int main(int argc, char **argv)
                errno = ret;
                PERROR("pthread_create health");
                retval = -1;
-               goto exit_health_thread;
+               goto exit_options;
        }
 
        /* Setup the dispatcher thread */
@@ -4005,14 +4411,6 @@ exit_dispatcher_thread:
                PERROR("pthread_join health_thread");
                retval = -1;
        }
-exit_health_thread:
-
-       utils_close_pipe(health_quit_pipe);
-exit_health_quit_pipe:
-
-exit_init_data:
-       health_app_destroy(health_relayd);
-exit_health_app_create:
 exit_options:
        /*
         * Wait for all pending call_rcu work to complete before tearing
@@ -4025,6 +4423,10 @@ exit_options:
        /* Ensure all prior call_rcu are done. */
        rcu_barrier();
 
+       if (thread_is_rcu_registered) {
+               rcu_unregister_thread();
+       }
+
        if (!retval) {
                exit(EXIT_SUCCESS);
        } else {
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