zdtm: test overmounting with shared parent works

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

test/zdtm/static/Makefile

@@ -269,6 +269,7 @@ TST_DIR		=				\
 		mount_paths			\
 		bind-mount			\
 		shared_mount_propagation	\
+		overmount_with_shared_parent	\
 		inotify00			\
 		inotify01			\
 		inotify02			\

test/zdtm/static/overmount_with_shared_parent.c

+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <linux/limits.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check overmount on shared parent works";
+const char *test_author	= "Pavel Tikhomirov <ptikhomirov@virtuozzo.com>";
+
+char *dirname;
+TEST_OPTION(dirname, string, "directory name", 1);
+
+int main(int argc, char **argv)
+{
+	char dir_a[PATH_MAX], dir_b[PATH_MAX], dir_c[PATH_MAX];
+	char dir_d[PATH_MAX], dir_a_c[PATH_MAX];
+
+	test_init(argc, argv);
+
+	mkdir(dirname, 0700);
+
+	if (mount(dirname, dirname, NULL, MS_BIND, NULL)) {
+		pr_perror("Unable to self bind mount %s", dirname);
+		return 1;
+	}
+
+	if (mount(NULL, dirname, NULL, MS_SHARED, NULL)) {
+		pr_perror("Unable to make shared mount %s", dirname);
+		return 1;
+	}
+
+	snprintf(dir_a, sizeof(dir_a), "%s/a", dirname);
+	snprintf(dir_d, sizeof(dir_d), "%s/d", dirname);
+	mkdir(dir_a, 0700);
+	mkdir(dir_d, 0700);
+
+	snprintf(dir_b, sizeof(dir_a), "%s/b", dir_a);
+	snprintf(dir_c, sizeof(dir_c), "%s/c", dir_b);
+	mkdir(dir_b, 0700);
+	mkdir(dir_c, 0700);
+
+	if (mount(dir_b, dir_a, NULL, MS_BIND, NULL)) {
+		pr_perror("Unable to bind mount %s to %s", dir_b, dir_a);
+		return 1;
+	}
+
+	snprintf(dir_a_c, sizeof(dir_a_c), "%s/c", dir_a);
+
+	if (mount(dir_d, dir_a_c, NULL, MS_BIND, NULL)) {
+		pr_perror("Unable to bind mount %s to %s", dir_d, dir_a_c);
+		return 1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	if (umount(dir_a_c)) {
+		pr_perror("Unable to umount %s", dir_a_c);
+		return 1;
+	}
+
+	if (umount(dir_a)) {
+		pr_perror("Unable to umount %s", dir_a);
+		return 1;
+	}
+
+	pass();
+	return 0;
+}

test/zdtm/static/overmount_with_shared_parent.desc

+{'flavor': 'ns uns', 'flags': 'suid'}