fusefs: fix a race in the pre-init tests

These tests allow the user to customize the INIT response.  But it's
necessary to block the daemon's service loop from running until those
expectations have been set.  This race has never caused failures before
simply due to luck.  But now it's failing on slower platforms.

PR:		296236
Reported by:	siva
MFC after:	2 weeks
Sponsored by:	ConnectWise
Reviewed by:	siva
Differential Revision: https://reviews.freebsd.org/D57781

3 files changed, 17 insertions, 3 deletions

diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc
index b9e4afbbea0b..0e395a4fabb3 100644
--- a/tests/sys/fs/fusefs/mockfs.cc
+++ b/tests/sys/fs/fusefs/mockfs.cc
@@ -550,9 +550,8 @@ MockFS::MockFS(int max_read, int max_readahead, bool allow_other,
 	if (0 != sigaction(SIGUSR1, &sa, NULL))
 		throw(std::system_error(errno, std::system_category(),
 			"Couldn't handle SIGUSR1"));
-	if (pthread_create(&m_daemon_id, NULL, service, (void*)this))
-		throw(std::system_error(errno, std::system_category(),
-			"Couldn't Couldn't start fuse thread"));
+	if (!no_auto_init)
+		start_service();
 }
 
 MockFS::~MockFS() {
@@ -1018,6 +1017,12 @@ void MockFS::read_request(mockfs_buf_in &in, ssize_t &res) {
 	ASSERT_TRUE(res == static_cast<ssize_t>(in.header.len) || m_quit);
 }
 
+void MockFS::start_service() {
+	if (pthread_create(&m_daemon_id, NULL, service, (void*)this))
+		throw(std::system_error(errno, std::system_category(),
+			"Couldn't Couldn't start fuse thread"));
+}
+
 void MockFS::write_response(const mockfs_buf_out &out) {
 	fd_set writefds;
 	pollfd fds[1];
diff --git a/tests/sys/fs/fusefs/mockfs.hh b/tests/sys/fs/fusefs/mockfs.hh
index c8f90c2f5402..19693e50d212 100644
--- a/tests/sys/fs/fusefs/mockfs.hh
+++ b/tests/sys/fs/fusefs/mockfs.hh
@@ -388,6 +388,9 @@ class MockFS {
 	/* Process FUSE requests endlessly */
 	void loop();
 
+	/* Begin processing requests from the kernel */
+	void start_service();
+
 	/*
 	 * Send an asynchronous notification to invalidate a directory entry.
 	 * Similar to libfuse's fuse_lowlevel_notify_inval_entry
diff --git a/tests/sys/fs/fusefs/pre-init.cc b/tests/sys/fs/fusefs/pre-init.cc
index 2d3257500304..70d7ddcdb0f4 100644
--- a/tests/sys/fs/fusefs/pre-init.cc
+++ b/tests/sys/fs/fusefs/pre-init.cc
@@ -102,6 +102,8 @@ TEST_F(PreInit, unmount_before_init)
 	})));
 	expect_destroy(0);
 
+	m_mock->start_service();
+
 	ASSERT_EQ(0, pthread_create(&th1, NULL, unmount1, NULL));
 	nap();	/* Wait for th1 to block in unmount() */
 	sem_post(&sem0);
@@ -147,6 +149,8 @@ TEST_F(PreInit, signal_during_unmount_before_init)
 		sem_wait(&sem0);
 	})));
 
+	m_mock->start_service();
+
 	if ((child = ::fork()) == 0) {
 		/*
 		 * In child.  This will block waiting for FUSE_INIT to complete
@@ -219,6 +223,8 @@ TEST_P(PreInitP, getattr_before_init)
 		out.body.attr.attr_valid = UINT64_MAX;
 	})));
 
+	m_mock->start_service();
+
 	EXPECT_EQ(0, stat("mountpoint", &sb));
 	EXPECT_EQ(nlink, sb.st_nlink);
 }