[LTP] [PATCH v4 05/13] Add listmount02 test

[Andrea Cervesato]

From: Andrea Cervesato <andrea.cervesato@suse.com>

This test verifies that listmount() is properly reading groups of
mount IDs.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                                  |   1 +
 testcases/kernel/syscalls/listmount/.gitignore    |   1 +
 testcases/kernel/syscalls/listmount/listmount02.c | 105 ++++++++++++++++++++++
 3 files changed, 107 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 48db6259b..13b6a28b9 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -731,6 +731,7 @@ linkat02 linkat02
 listen01 listen01
 
 listmount01 listmount01
+listmount02 listmount02
 
 listxattr01 listxattr01
 listxattr02 listxattr02
diff --git a/testcases/kernel/syscalls/listmount/.gitignore b/testcases/kernel/syscalls/listmount/.gitignore
index 5257b298c..30bbf9f02 100644
--- a/testcases/kernel/syscalls/listmount/.gitignore
+++ b/testcases/kernel/syscalls/listmount/.gitignore
@@ -1 +1,2 @@
 listmount01
+listmount02
diff --git a/testcases/kernel/syscalls/listmount/listmount02.c b/testcases/kernel/syscalls/listmount/listmount02.c
new file mode 100644
index 000000000..950d660d7
--- /dev/null
+++ b/testcases/kernel/syscalls/listmount/listmount02.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * This test verifies that listmount() is properly reading groups of mount IDs,
+ * checking that both oneshoot and iterator API for listmount() return the same
+ * array.
+ *
+ * [Algorithm]
+ *
+ * - move into a new unshared namespace
+ * - mount() our new root inside temporary folder
+ * - generate a full mounts tree inside root folder, doubling the number of
+ *   mounted filesystems each bind mount
+ * - read the full list of mounted IDs using listmount(LSMT_ROOT, ..)
+ * - read the list of mounted IDs using groups of fixed size
+ * - compare the first mount list with the second mount list
+ */
+
+#include "listmount.h"
+#include "lapi/sched.h"
+
+#define MNTPOINT "mntpoint"
+#define BIND_MOUNTS 7
+#define GROUPS_SIZE 3
+#define LISTSIZE (1 << BIND_MOUNTS)
+
+static void run(void)
+{
+	ssize_t ret;
+	size_t id, tot_ids, count = 0;
+	uint64_t mount_ids[LISTSIZE];
+	uint64_t list[LISTSIZE];
+
+	for (int i = 0; i < BIND_MOUNTS; i++)
+		SAFE_MOUNT("/", "/", NULL, MS_BIND, NULL);
+
+	tst_res(TINFO, "Reading all %d mount IDs in once", LISTSIZE);
+
+	TST_EXP_POSITIVE(listmount(LSMT_ROOT, 0, mount_ids, LISTSIZE, 0));
+	if (TST_RET == -1)
+		goto end;
+
+	tot_ids = (size_t)TST_RET;
+
+	if (tot_ids != LISTSIZE) {
+		tst_res(TFAIL, "listmount() returned %lu but %d was expected",
+			tot_ids, LISTSIZE);
+		goto end;
+	}
+
+	tst_res(TINFO, "Reading groups of %d mount IDs", GROUPS_SIZE);
+
+	while (count < LISTSIZE) {
+		id = count ? list[count - 1] : 0;
+		ret = listmount(LSMT_ROOT, id, list + count, GROUPS_SIZE, 0);
+
+		tst_res(TDEBUG, "listmount(LSMT_ROOT, %lu, list + %lu, %d, 0)",
+			id, count, GROUPS_SIZE);
+
+		if (ret == -1) {
+			tst_res(TFAIL, "listmount() failed with %s", tst_strerrno(errno));
+			goto end;
+		}
+
+		count += ret;
+
+		if (TST_RET < GROUPS_SIZE)
+			break;
+	}
+
+	for (size_t i = 0; i < LISTSIZE; i++) {
+		if (mount_ids[i] != list[i]) {
+			tst_res(TFAIL, "Mount ID differs at %ld index", i);
+			goto end;
+		}
+	}
+
+	tst_res(TPASS, "All mount IDs have been correctly read");
+
+end:
+	for (int i = 0; i < BIND_MOUNTS; i++)
+		SAFE_UMOUNT("/");
+}
+
+static void setup(void)
+{
+	SAFE_UNSHARE(CLONE_NEWNS);
+	SAFE_CHROOT(MNTPOINT);
+
+	SAFE_MOUNT("", "/", NULL, MS_REC | MS_SHARED, NULL);
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.forks_child = 1,
+	.min_kver = "6.8",
+	.mount_device = 1,
+	.mntpoint = MNTPOINT,
+};

-- 
2.43.0