tempfs: check inaccessible tempfs mounts

criu dump should return an error in this case
Signed-off-by: Andrew Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

test/zdtm/static/Makefile

@@ -205,6 +205,7 @@ TST_DIR		=				\
 		overmount_fifo			\
 		overmount_sock			\
 		tempfs				\
+		tempfs_overmounted		\
 		tempfs_ro			\
 		tempfs_subns			\
 		mnt_ro_bind			\

test/zdtm/static/tempfs_overmounted.c

+#include <stdbool.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <linux/limits.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check tmpfs mount";
+const char *test_author	= "Pavel Emelianov <xemul@parallels.com>";
+
+char *dirname;
+TEST_OPTION(dirname, string, "directory name", 1);
+
+int main(int argc, char **argv)
+{
+	test_init(argc, argv);
+
+	mkdir(dirname, 0700);
+	if (mount("none", dirname, "tmpfs", 0, "") < 0) {
+		fail("Can't mount tmpfs");
+		return 1;
+	}
+	if (mount("none", dirname, "tmpfs", 0, "") < 0) {
+		fail("Can't mount tmpfs");
+		return 1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	pass();
+	return 0;
+}

test/zdtm/static/tempfs_overmounted.desc

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