[pve-devel] [PATCH cluster v3] pmxcfs: only exit parent when successfully started

[Dominik Csapak]

since systemd depends that parent exits 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

this could also affect every service which has an
After=pve-cluster

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v2:
* move the variable declaration down
* use a errno_tmp variable to save the errorcode
* kill the child in case of an error
 data/src/pmxcfs.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/data/src/pmxcfs.c b/data/src/pmxcfs.c
index 6047ad0..de6163a 100644
--- a/data/src/pmxcfs.c
+++ b/data/src/pmxcfs.c
@@ -775,6 +775,7 @@ int main(int argc, char *argv[])
 {
 	int ret = -1;
 	int lockfd = -1;
+	int pipefd[2];
 
 	gboolean foreground = FALSE;
 	gboolean force_local_mode = FALSE;
@@ -954,17 +955,39 @@ int main(int argc, char *argv[])
 	fuse_set_signal_handlers(fuse_get_session(fuse));
 
 	if (!foreground) {
+		if (pipe(pipefd) == -1) {
+			cfs_critical("pipe error: %s", strerror(errno));
+			goto err;
+		}
+
 		pid_t cpid = fork();
 
 		if (cpid == -1) {
 			cfs_critical("failed to daemonize program - %s", strerror (errno));
 			goto err;
 		} else if (cpid) {
+			int readbytes, errno_tmp;
+			char readbuffer;
+			close(pipefd[1]);
+			readbytes = read(pipefd[0], &readbuffer, sizeof(readbuffer));
+			errno_tmp = errno;
+			close(pipefd[0]);
+			if (readbytes == -1) {
+				cfs_critical("read error: %s", strerror(errno_tmp));
+				kill(cpid, SIGKILL);
+				goto err;
+			} else if (readbytes != 1 || readbuffer != '1') {
+				cfs_critical("child failed to send '1'");
+				kill(cpid, SIGKILL);
+				goto err;
+			}
+			/* child finished starting up */
 			write_pidfile(cpid);
 			qb_log_fini();
 			_exit (0);
 		} else {
 			int nullfd;
+			close(pipefd[0]);
 
 			chroot("/");
 
@@ -1022,6 +1045,12 @@ int main(int argc, char *argv[])
 
 	unlink(RESTART_FLAG_FILE);
 
+	if (!foreground) {
+		/* finished starting up, signaling parent */
+		write(pipefd[1], "1", 1);
+		close(pipefd[1]);
+	}
+
 	ret = fuse_loop_mt(fuse);
 
 	open(RESTART_FLAG_FILE, O_CREAT|O_NOCTTY|O_NONBLOCK);
-- 
2.11.0