[pve-devel] [PATCH cluster] pmxcfs: only exit parent when successfully started

[Dominik Csapak]

since systemd depends that the pid file is written only
when the service is actually started, we need to wait for the
child to get to the point where it starts the fuse loop
and signal the parent to now exit and write the pid file

without this, we had an issue, where the
ExecStartPost hook (which runs pvecm updatecerts) did not run reliably,
but which is necessary to setup the nodes/ dir in /etc/pve
and generating the ssl certificates

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
 data/src/pmxcfs.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/data/src/pmxcfs.c b/data/src/pmxcfs.c
index 6047ad0..f4a329f 100644
--- a/data/src/pmxcfs.c
+++ b/data/src/pmxcfs.c
@@ -61,6 +61,7 @@
 #define RESTART_FLAG_FILE RUNDIR "/cfs-restart-flag"
 
 #define CFSDIR "/etc/pve"
+#define OK_MESSAGE "OK"
 
 cfs_t cfs = {
 	.debug = 0,
@@ -775,6 +776,9 @@ int main(int argc, char *argv[])
 {
 	int ret = -1;
 	int lockfd = -1;
+	int pipefd[2];
+	int readbytes;
+	char readbuffer[strlen(OK_MESSAGE)];
 
 	gboolean foreground = FALSE;
 	gboolean force_local_mode = FALSE;
@@ -954,17 +958,31 @@ int main(int argc, char *argv[])
 	fuse_set_signal_handlers(fuse_get_session(fuse));
 
 	if (!foreground) {
+		pipe(pipefd);
 		pid_t cpid = fork();
 
 		if (cpid == -1) {
 			cfs_critical("failed to daemonize program - %s", strerror (errno));
 			goto err;
 		} else if (cpid) {
-			write_pidfile(cpid);
-			qb_log_fini();
-			_exit (0);
+			close(pipefd[1]);
+			readbytes = read(pipefd[0], readbuffer, sizeof(readbuffer));
+			close(pipefd[0]);
+			if (readbytes == 2 &&
+			    strncmp(readbuffer, OK_MESSAGE, strlen(OK_MESSAGE)) == 0) {
+			    /* child finished starting up */
+			    write_pidfile(cpid);
+			    qb_log_fini();
+			    _exit (0);
+			} else {
+			    /* something went wrong */
+			    cfs_critical("child failed to send OK");
+			    goto err;
+			}
+
 		} else {
 			int nullfd;
+			close(pipefd[0]);
 
 			chroot("/");
 
@@ -1022,6 +1040,10 @@ int main(int argc, char *argv[])
 
 	unlink(RESTART_FLAG_FILE);
 
+	/* finished starting up, signaling parent */
+	write(pipefd[1], OK_MESSAGE, strlen(OK_MESSAGE));
+	close(pipefd[1]);
+
 	ret = fuse_loop_mt(fuse);
 
 	open(RESTART_FLAG_FILE, O_CREAT|O_NOCTTY|O_NONBLOCK);
-- 
2.11.0