[Devel] [PATCH VZ10 v3 9/9] selftests/ve: Add mount accounting selftest
Vladimir Riabchun
vladimir.riabchun at virtuozzo.com
Mon Jul 27 00:30:29 MSK 2026
There are 4 test cases, covered in the new test:
1. Simple mount accouting correctness, just mount/umount.
2. Verification of correct limit hits and changes, including
negative values and partially successful mounts (step 4).
3. Test that pseudosuper changes don't break mount counting.
4. Failcount feature verification.
https://virtuozzo.atlassian.net/browse/VSTOR-135520
Feature: per-ve failcounters
Signed-off-by: Vladimir Riabchun <vladimir.riabchun at virtuozzo.com>
---
tools/testing/selftests/ve/.gitignore | 1 +
tools/testing/selftests/ve/Makefile | 1 +
.../selftests/ve/ve_mount_accounting_test.c | 339 ++++++++++++++++++
3 files changed, 341 insertions(+)
create mode 100644 tools/testing/selftests/ve/ve_mount_accounting_test.c
diff --git a/tools/testing/selftests/ve/.gitignore b/tools/testing/selftests/ve/.gitignore
index afa4c568c2c9..3df4d05888dc 100644
--- a/tools/testing/selftests/ve/.gitignore
+++ b/tools/testing/selftests/ve/.gitignore
@@ -1,2 +1,3 @@
ve_ns_owner_test
ve_perms_test
+ve_mount_accounting_test
diff --git a/tools/testing/selftests/ve/Makefile b/tools/testing/selftests/ve/Makefile
index ec40cbc7b3a1..c6efe7c4b4fb 100644
--- a/tools/testing/selftests/ve/Makefile
+++ b/tools/testing/selftests/ve/Makefile
@@ -4,5 +4,6 @@ CFLAGS += -g -Wall -O2
TEST_GEN_PROGS += ve_ns_owner_test
TEST_GEN_PROGS += ve_perms_test
+TEST_GEN_PROGS += ve_mount_accounting_test
include ../lib.mk
diff --git a/tools/testing/selftests/ve/ve_mount_accounting_test.c b/tools/testing/selftests/ve/ve_mount_accounting_test.c
new file mode 100644
index 000000000000..8bd208422b09
--- /dev/null
+++ b/tools/testing/selftests/ve/ve_mount_accounting_test.c
@@ -0,0 +1,339 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ve_mount_accounting selftests
+ *
+ * Tests to check the correctness of mount accounting.
+ */
+#define _GNU_SOURCE
+#include <linux/sched.h>
+#include <linux/mount.h>
+#include <sched.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+#include <linux/limits.h>
+#include <errno.h>
+
+#include "../kselftest_harness.h"
+#include "ve_selftest.h"
+
+#define TMP_DIR "/ve-mnt-tmp/"
+#define VE_MOUNTS_MAX 128
+
+static int set_pseudosuper(int cgv2_fd, int ctid, int value)
+{
+ char path[64];
+
+ snprintf(path, sizeof(path), "%d/ve.pseudosuper", ctid);
+ return write_u64_at(cgv2_fd, path, value);
+}
+
+static int _create_mount(void *id_ptr)
+{
+ char path[PATH_MAX];
+ int id = *(int *)id_ptr, ret;
+
+ snprintf(path, sizeof(path), TMP_DIR "%d", id);
+
+ if (mkdir(path, 0755) < 0) {
+ fprintf(stderr, "Failed to create directory %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ ret = mount("tmpfs", path, "tmpfs", 0, "size=1M");
+ if (!ret)
+ return 0;
+ fprintf(stderr, "Failed to mount tmpfs to %s: %s\n", path, strerror(errno));
+
+ rmdir(path);
+ return ret;
+}
+
+static int create_mount(int cgv2_fd, int ctid, int id)
+{
+ int ret = run_in_ve(cgv2_fd, ctid, CLONE_NEWVE, _create_mount, &id);
+ /*
+ * If mount fails, cleanup by free_vfsmnt will be called
+ * via call_rcu, need to wait for update.
+ */
+ sleep(1);
+ return ret;
+}
+
+static int _destroy_mount(void *id_ptr)
+{
+ char path[PATH_MAX];
+ struct stat st;
+ int id = *(int *)id_ptr;
+
+ snprintf(path, sizeof(path), TMP_DIR "%d", id);
+
+ if (stat(path, &st))
+ return 1;
+ if (umount(path)) {
+ fprintf(stderr, "failed to umount directory %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ if (rmdir(path)) {
+ fprintf(stderr, "failed to remove directory %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ return 0;
+}
+
+static int destroy_mount(int cgv2_fd, int ctid, int id)
+{
+ int ret = run_in_ve(cgv2_fd, ctid, CLONE_NEWVE, _destroy_mount, &id);
+ /* free_vfsmnt is called via call_rcu, need to wait for update */
+ sleep(1);
+ return ret;
+}
+
+static int get_mount_cost(int cgv2_fd, int ctid)
+{
+ int avail1, avail2;
+ char path[64];
+
+ snprintf(path, sizeof(path), "%d/ve.mnt_avail_nr", ctid);
+ if (read_s32_at(cgv2_fd, path, &avail1) ||
+ create_mount(cgv2_fd, ctid, 0) ||
+ read_s32_at(cgv2_fd, path, &avail2) ||
+ destroy_mount(cgv2_fd, ctid, 0))
+ return -1;
+
+ return avail1 - avail2;
+}
+
+/* Expect mount success and return new avail value */
+static int mount_and_get_avail(struct __test_metadata *_metadata,
+ int cgv2_fd, int ctid, int mnt_id)
+{
+ char path_avail[64];
+ int mnt_avail_nr;
+
+ snprintf(path_avail, sizeof(path_avail), "%d/ve.mnt_avail_nr", ctid);
+
+ ASSERT_EQ(create_mount(cgv2_fd, ctid, mnt_id), 0);
+ ASSERT_EQ(read_s32_at(cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ return mnt_avail_nr;
+}
+
+/* Expect mount failure and ensure intact avail number */
+static void assert_mount_fails(struct __test_metadata *_metadata,
+ int cgv2_fd, int ctid, int mnt_id, int avail_count)
+{
+ char path_avail[64];
+ int mnt_avail_nr;
+
+ snprintf(path_avail, sizeof(path_avail), "%d/ve.mnt_avail_nr", ctid);
+
+ ASSERT_EQ(read_s32_at(cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, avail_count);
+ ASSERT_LT(create_mount(cgv2_fd, ctid, mnt_id), 0);
+ ASSERT_EQ(read_s32_at(cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, avail_count);
+}
+
+FIXTURE(ve_mnt_acc)
+{
+ int cgv2_fd;
+ int ctid;
+};
+
+FIXTURE_SETUP(ve_mnt_acc)
+{
+ unsigned long long initial_mnt_avail_nr;
+ char path[64];
+
+ self->cgv2_fd = mount_cg2_fd();
+ ASSERT_GE(self->cgv2_fd, 0);
+ mkdir(TMP_DIR, 0755);
+
+ ASSERT_EQ(write_file_at(self->cgv2_fd, "cgroup.subtree_control",
+ VE_CONTROLLERS), 0);
+
+ self->ctid = make_ve(self->cgv2_fd, CTID_MIN);
+ ASSERT_GE(self->ctid, 0);
+
+ snprintf(path, sizeof(path), "%d/ve.mnt_max_nr", self->ctid);
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path, VE_MOUNTS_MAX), 0);
+
+ /*
+ * The new ve cgroup has not been entered by anything yet, so its
+ * mnt_avail_nr counter should be VE_MOUNTS_MAX.
+ */
+ snprintf(path, sizeof(path), "%d/ve.mnt_avail_nr", self->ctid);
+ ASSERT_EQ(read_u64_at(self->cgv2_fd, path, &initial_mnt_avail_nr), 0);
+ ASSERT_EQ(initial_mnt_avail_nr, VE_MOUNTS_MAX);
+};
+
+FIXTURE_TEARDOWN(ve_mnt_acc)
+{
+ destroy_ve(self->cgv2_fd, self->ctid);
+ close(self->cgv2_fd);
+ rmdir(TMP_DIR);
+}
+
+/* Simple test to check mount/umount accounting correctness */
+TEST_F(ve_mnt_acc, mount_umount)
+{
+ int original_mnt_avail, mnt_avail_nr;
+ char path[64];
+
+ snprintf(path, sizeof(path), "%d/ve.mnt_avail_nr", self->ctid);
+
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path, &original_mnt_avail), 0);
+
+ ASSERT_LT(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 0),
+ original_mnt_avail);
+
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 0), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, original_mnt_avail);
+}
+
+/* Test mount limit hits */
+TEST_F(ve_mnt_acc, hit_limits)
+{
+ int original_mnt_avail, mnt_avail_nr, mnt_cost;
+ int original_have_mnt;
+ char path_avail[64], path_max_nr[64];
+
+ snprintf(path_avail, sizeof(path_avail), "%d/ve.mnt_avail_nr", self->ctid);
+ snprintf(path_max_nr, sizeof(path_max_nr), "%d/ve.mnt_max_nr", self->ctid);
+
+ mnt_cost = get_mount_cost(self->cgv2_fd, self->ctid);
+ ASSERT_GE(mnt_cost, 1);
+
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &original_mnt_avail), 0);
+ original_have_mnt = VE_MOUNTS_MAX - original_mnt_avail;
+
+ /* Step 1: reduce number of available mounts to mnt_cost */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr, original_have_mnt + 1 * mnt_cost), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, 1 * mnt_cost);
+
+ /* Step 2: do one mount, no mounts should be available */
+ ASSERT_EQ(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 0),
+ 0);
+
+ /* Step 3: check that one more mount falils */
+ assert_mount_fails(_metadata, self->cgv2_fd, self->ctid, 1, 0);
+
+ /* Step 4: increase mount limit a little bit, mount should still fail */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr,
+ original_have_mnt + 2 * mnt_cost - 1), 0);
+ assert_mount_fails(_metadata, self->cgv2_fd, self->ctid, 1, mnt_cost - 1);
+
+ /* Step 5: increase by 1 and win now */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr, original_have_mnt + 2 * mnt_cost), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, mnt_cost);
+
+ ASSERT_EQ(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 1),
+ 0);
+
+ /* Step 6: reduce mnt_max_nr so we have more mounts than allowed */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr, original_have_mnt + 1 * mnt_cost), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, -1 * mnt_cost);
+
+ /* Step 7: try to do mount when avail < 0, ensure number is intact */
+ assert_mount_fails(_metadata, self->cgv2_fd, self->ctid, 2, -1 * mnt_cost);
+
+ /* Step 8: remove one mount, check avail value update, mount should fail */
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 0), 0);
+ assert_mount_fails(_metadata, self->cgv2_fd, self->ctid, 2, 0);
+
+ /* Step 9: remove one more mount and check that new mount succeeds */
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 1), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, 1 * mnt_cost);
+ ASSERT_EQ(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 2),
+ 0);
+
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 2), 0);
+}
+
+/* Test correct accounting when playing with pseudosuper */
+TEST_F(ve_mnt_acc, pseudosuper)
+{
+ int original_mnt_avail, mnt_avail_nr;
+ char path_avail[64];
+
+ snprintf(path_avail, sizeof(path_avail), "%d/ve.mnt_avail_nr", self->ctid);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &original_mnt_avail), 0);
+
+ /* Case 1: pseudosuper = 1 before mount */
+ set_pseudosuper(self->cgv2_fd, self->ctid, 1);
+ /* 1.1: mount and umount under pseudosuper. Check that mount/umount cost is 0 */
+ ASSERT_EQ(get_mount_cost(self->cgv2_fd, self->ctid), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, original_mnt_avail);
+
+ /* 1.2: mount under pseudosuper, umount without */
+ set_pseudosuper(self->cgv2_fd, self->ctid, 1);
+ ASSERT_EQ(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 0),
+ original_mnt_avail);
+ set_pseudosuper(self->cgv2_fd, self->ctid, 0);
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 0), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, original_mnt_avail);
+
+ /* Case 2: pseudosuper = 0 before mount, 1 before umount */
+ set_pseudosuper(self->cgv2_fd, self->ctid, 0);
+ ASSERT_LT(mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 0),
+ original_mnt_avail);
+ set_pseudosuper(self->cgv2_fd, self->ctid, 1);
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 0), 0);
+ ASSERT_EQ(read_s32_at(self->cgv2_fd, path_avail, &mnt_avail_nr), 0);
+ ASSERT_EQ(mnt_avail_nr, original_mnt_avail);
+}
+
+/* Test failcount feature */
+TEST_F(ve_mnt_acc, failcount)
+{
+ char path_fc[64], failcount_str[512], path_max_nr[64];
+
+ snprintf(path_fc, sizeof(path_fc), "%d/ve.failcount", self->ctid);
+ snprintf(path_max_nr, sizeof(path_max_nr), "%d/ve.mnt_max_nr", self->ctid);
+
+ ASSERT_GE(read_file_at(self->cgv2_fd, path_fc,
+ failcount_str, sizeof(failcount_str)), 0);
+ ASSERT_TRUE(strstr(failcount_str, "mnt: 0\n") != NULL);
+
+ /* Check successful mount doesn't affect failcount */
+ mount_and_get_avail(_metadata, self->cgv2_fd, self->ctid, 0);
+ ASSERT_GE(read_file_at(self->cgv2_fd, path_fc,
+ failcount_str, sizeof(failcount_str)), 0);
+ ASSERT_TRUE(strstr(failcount_str, "mnt: 0\n") != NULL);
+ ASSERT_EQ(destroy_mount(self->cgv2_fd, self->ctid, 0), 0);
+
+ /* Check failcount update when mount fails */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr, 0), 0);
+ ASSERT_LT(create_mount(self->cgv2_fd, self->ctid, 1), 0);
+ ASSERT_GE(read_file_at(self->cgv2_fd, path_fc,
+ failcount_str, sizeof(failcount_str)), 0);
+ ASSERT_TRUE(strstr(failcount_str, "mnt: 1\n") != NULL);
+
+ /* Check failcount flush */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_fc, 0), 0);
+ ASSERT_GE(read_file_at(self->cgv2_fd, path_fc,
+ failcount_str, sizeof(failcount_str)), 0);
+ ASSERT_TRUE(strstr(failcount_str, "mnt: 0\n") != NULL);
+
+ /* Check failcount update when mount fails again */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_max_nr, 0), 0);
+ ASSERT_LT(create_mount(self->cgv2_fd, self->ctid, 1), 0);
+ ASSERT_GE(read_file_at(self->cgv2_fd, path_fc,
+ failcount_str, sizeof(failcount_str)), 0);
+ ASSERT_TRUE(strstr(failcount_str, "mnt: 1\n") != NULL);
+}
+
+TEST_HARNESS_MAIN
--
2.47.1
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