From 8f0a91b5192b72eb8b0f06e04ef3515d0397fcb8 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Fri, 5 Apr 2019 18:20:25 +0200

Subject: [PATCH] journald: add API to move logging from /var to /run again

We now have this nice little Varlink API, let's beef it up a bit.

[dtardon: This diverges from the upstream commit in two ways: One is

that the new action is bound to a signal, as varlink is not available.

The other is that this introduces a new "flag" file

/run/systemd/journal/relinquished, which is essentially the opposite of

/run/systemd/journal/flushed (hence at most one of them may exist at any

time).]

(cherry picked from commit b4e26d1d8e582d78e67ed766177f10e8e194404c)

Related: #1873540

---

 src/journal/journald-server.c | 64 ++++++++++++++++++++++++++++-------

 1 file changed, 51 insertions(+), 13 deletions(-)

diff --git a/src/journal/journald-server.c b/src/journal/journald-server.c

index 7632e2d9d0..279a32768c 100644

--- a/src/journal/journald-server.c

+++ b/src/journal/journald-server.c

@@ -283,13 +283,14 @@ static bool flushed_flag_is_set(void) {

         return access("/run/systemd/journal/flushed", F_OK) >= 0;

 }

-static int system_journal_open(Server *s, bool flush_requested) {

+static int system_journal_open(Server *s, bool flush_requested, bool relinquish_requested) {

         const char *fn;

         int r = 0;

         if (!s->system_journal &&

             IN_SET(s->storage, STORAGE_PERSISTENT, STORAGE_AUTO) &&

-            (flush_requested || flushed_flag_is_set())) {

+            (flush_requested || flushed_flag_is_set()) &&

+            !relinquish_requested) {

                 /* If in auto mode: first try to create the machine

                  * path, but not the prefix.

@@ -331,7 +332,7 @@ static int system_journal_open(Server *s, bool flush_requested) {

                 fn = strjoina(s->runtime_storage.path, "/system.journal");

-                if (s->system_journal) {

+                if (s->system_journal && !relinquish_requested) {

                         /* Try to open the runtime journal, but only

                          * if it already exists, so that we can flush

@@ -386,7 +387,7 @@ static JournalFile* find_journal(Server *s, uid_t uid) {

          * else that's left the journals as NULL).

          *

          * Fixes https://github.com/systemd/systemd/issues/3968 */

-        (void) system_journal_open(s, false);

+        (void) system_journal_open(s, false, false);

         /* We split up user logs only on /var, not on /run. If the

          * runtime file is open, we write to it exclusively, in order

@@ -964,7 +965,7 @@ int server_flush_to_var(Server *s, bool require_flag_file) {

         char ts[FORMAT_TIMESPAN_MAX];

         usec_t start;

         unsigned n = 0;

-        int r;

+        int r, k;

         assert(s);

@@ -977,7 +978,7 @@ int server_flush_to_var(Server *s, bool require_flag_file) {

         if (require_flag_file && !flushed_flag_is_set())

                 return 0;

-        (void) system_journal_open(s, true);

+        (void) system_journal_open(s, true, false);

         if (!s->system_journal)

                 return 0;

@@ -1056,6 +1057,13 @@ finish:

                                           n),

                               NULL);

+        if (unlink("/run/systemd/journal/relinquished") < 0 && errno != ENOENT)

+                log_warning_errno(errno, "Failed to unlink /run/systemd/journal/relinquished, ignoring: %m");

+

+        k = touch("/run/systemd/journal/flushed");

+        if (k < 0)

+                log_warning_errno(k, "Failed to touch /run/systemd/journal/flushed, ignoring: %m");

+

         return r;

 }

@@ -1180,7 +1188,6 @@ int server_process_datagram(sd_event_source *es, int fd, uint32_t revents, void

 static int dispatch_sigusr1(sd_event_source *es, const struct signalfd_siginfo *si, void *userdata) {

         Server *s = userdata;

-        int r;

         assert(s);

@@ -1190,10 +1197,6 @@ static int dispatch_sigusr1(sd_event_source *es, const struct signalfd_siginfo *

         server_sync(s);

         server_vacuum(s, false);

-        r = touch("/run/systemd/journal/flushed");

-        if (r < 0)

-                log_warning_errno(r, "Failed to touch /run/systemd/journal/flushed, ignoring: %m");

-

         server_space_usage_message(s, NULL);

         return 0;

 }

@@ -1250,12 +1253,43 @@ static int dispatch_sigrtmin1(sd_event_source *es, const struct signalfd_siginfo

         return 0;

 }

+

+static int dispatch_sigrtmin2(sd_event_source *es, const struct signalfd_siginfo *si, void *userdata) {

+        Server *s = userdata;

+        int r;

+

+        assert(s);

+

+        if (s->storage == STORAGE_NONE)

+                return 0;

+

+        if (s->runtime_journal && !s->system_journal)

+                return 0;

+

+        log_debug("Received request to relinquish /var from PID " PID_FMT, si->ssi_pid);

+

+        (void) system_journal_open(s, false, true);

+

+        s->system_journal = journal_file_close(s->system_journal);

+        ordered_hashmap_clear_with_destructor(s->user_journals, journal_file_close);

+        set_clear_with_destructor(s->deferred_closes, journal_file_close);

+

+        if (unlink("/run/systemd/journal/flushed") < 0 && errno != ENOENT)

+                log_warning_errno(errno, "Failed to unlink /run/systemd/journal/flushed, ignoring: %m")  ;

+

+        r = write_timestamp_file_atomic("/run/systemd/journal/relinquished", now(CLOCK_MONOTONIC));

+        if (r < 0)

+                log_warning_errno(r, "Failed to write /run/systemd/journal/relinquished, ignoring: %m");

+

+        return 0;

+}

+

 static int setup_signals(Server *s) {

         int r;

         assert(s);

-        assert_se(sigprocmask_many(SIG_SETMASK, NULL, SIGINT, SIGTERM, SIGUSR1, SIGUSR2, SIGRTMIN+1, -1) >= 0);

+        assert_se(sigprocmask_many(SIG_SETMASK, NULL, SIGINT, SIGTERM, SIGUSR1, SIGUSR2, SIGRTMIN+1, SIGRTMIN+2, -1) >= 0);

         r = sd_event_add_signal(s->event, &s->sigusr1_event_source, SIGUSR1, dispatch_sigusr1, s);

         if (r < 0)

@@ -1294,6 +1328,10 @@ static int setup_signals(Server *s) {

         if (r < 0)

                 return r;

+        r = sd_event_add_signal(s->event, &s->sigrtmin1_event_source, SIGRTMIN+2, dispatch_sigrtmin2, s);

+        if (r < 0)

+                return r;

+

         r = sd_event_source_set_priority(s->sigrtmin1_event_source, SD_EVENT_PRIORITY_NORMAL+15);

         if (r < 0)

                 return r;

@@ -1876,7 +1914,7 @@ int server_init(Server *s) {

         (void) client_context_acquire_default(s);

-        return system_journal_open(s, false);

+        return system_journal_open(s, false, false);

 }

 void server_maybe_append_tags(Server *s) {