journald: Support journald.conf.d directories in the usual search paths

Makefile-man.am

@@ -148,6 +148,7 @@ MANPAGES_ALIAS += \
 	man/SD_NOTICE.3 \
 	man/SD_WARNING.3 \
 	man/init.1 \
+	man/journald.conf.d.5 \
 	man/poweroff.8 \
 	man/reboot.8 \
 	man/sd_id128_equal.3 \
@@ -256,6 +257,7 @@ man/SD_LISTEN_FDS_START.3: man/sd_listen_fds.3
 man/SD_NOTICE.3: man/sd-daemon.3
 man/SD_WARNING.3: man/sd-daemon.3
 man/init.1: man/systemd.1
+man/journald.conf.d.5: man/journald.conf.5
 man/poweroff.8: man/halt.8
 man/reboot.8: man/halt.8
 man/sd_id128_equal.3: man/sd-id128.3
@@ -416,6 +418,9 @@ man/SD_WARNING.html: man/sd-daemon.html
 man/init.html: man/systemd.html
 	$(html-alias)
 
+man/journald.conf.d.html: man/journald.conf.html
+	$(html-alias)
+
 man/poweroff.html: man/halt.html
 	$(html-alias)
 

man/journald.conf.xml

@@ -22,7 +22,8 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
 
-<refentry id="journald.conf">
+<refentry id="journald.conf"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
         <refentryinfo>
                 <title>journald.conf</title>
                 <productname>systemd</productname>
@@ -44,22 +45,29 @@
 
         <refnamediv>
                 <refname>journald.conf</refname>
-                <refpurpose>Journal service configuration file</refpurpose>
+                <refname>journald.conf.d</refname>
+                <refpurpose>Journal service configuration files</refpurpose>
         </refnamediv>
 
         <refsynopsisdiv>
                 <para><filename>/etc/systemd/journald.conf</filename></para>
+                <para><filename>/etc/systemd/journald.conf.d/*.conf</filename></para>
+                <para><filename>/run/systemd/journald.conf.d/*.conf</filename></para>
+                <para><filename>/usr/lib/systemd/journald.conf.d/*.conf</filename></para>
         </refsynopsisdiv>
 
         <refsect1>
                 <title>Description</title>
 
-                <para>This file configures various parameters of the
+                <para>These files configure various parameters of the
                 systemd journal service,
                 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 
         </refsect1>
 
+        <xi:include href="standard-conf.xml" xpointer="confd" />
+        <xi:include href="standard-conf.xml" xpointer="conf" />
+
         <refsect1>
                 <title>Options</title>
 

src/journal/journald-server.c

@@ -1351,10 +1351,11 @@ static int server_parse_proc_cmdline(Server *s) {
 static int server_parse_config_file(Server *s) {
         assert(s);
 
-        return config_parse(NULL, "/etc/systemd/journald.conf", NULL,
-                            "Journal\0",
-                            config_item_perf_lookup, journald_gperf_lookup,
-                            false, false, true, s);
+        return config_parse_many("/etc/systemd/journald.conf",
+                                 CONF_DIRS_NULSTR("systemd/journald.conf"),
+                                 "Journal\0",
+                                 config_item_perf_lookup, journald_gperf_lookup,
+                                 false, s);
 }
 
 static int server_dispatch_sync(sd_event_source *es, usec_t t, void *userdata) {

src/journal/journald.conf

@@ -5,6 +5,9 @@
 #  the Free Software Foundation; either version 2.1 of the License, or
 #  (at your option) any later version.
 #
+# You can override the directives in this file by creating files in
+# /etc/systemd/journald.conf.d/*.conf.
+#
 # See journald.conf(5) for details
 
 [Journal]