[LTP] [PATCH v2 3/4] Add cachestat02 test

[Andrea Cervesato]

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

This test verifies that cachestat() syscall is properly counting cached
pages written inside a shared memory.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
 runtest/syscalls                                  |  1 +
 testcases/kernel/syscalls/cachestat/.gitignore    |  1 +
 testcases/kernel/syscalls/cachestat/cachestat02.c | 89 +++++++++++++++++++++++
 3 files changed, 91 insertions(+)

diff --git a/runtest/syscalls b/runtest/syscalls
index 9a1827e88..887ac217b 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -63,6 +63,7 @@ capset04 capset04
 cacheflush01 cacheflush01
 
 cachestat01 cachestat01
+cachestat02 cachestat02
 
 chdir01 chdir01
 chdir01A symlink01 -T chdir01
diff --git a/testcases/kernel/syscalls/cachestat/.gitignore b/testcases/kernel/syscalls/cachestat/.gitignore
index daea1f4be..0f70fb801 100644
--- a/testcases/kernel/syscalls/cachestat/.gitignore
+++ b/testcases/kernel/syscalls/cachestat/.gitignore
@@ -1 +1,2 @@
 cachestat01
+cachestat02
diff --git a/testcases/kernel/syscalls/cachestat/cachestat02.c b/testcases/kernel/syscalls/cachestat/cachestat02.c
new file mode 100644
index 000000000..d71f5dab5
--- /dev/null
+++ b/testcases/kernel/syscalls/cachestat/cachestat02.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2024 SUSE LLC Andrea Cervesato <andrea.cervesato@suse.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * This test verifies that cachestat() syscall is properly counting cached pages
+ * written inside a shared memory.
+ *
+ * [Algorithm]
+ *
+ * - create a shared memory with a specific amount of pages
+ * - monitor file with cachestat()
+ * - check if the right amount of pages have been moved into cache
+ */
+
+#include "cachestat.h"
+
+#define FILENAME "myfile.bin"
+
+static int page_size;
+static char *page_data;
+static struct cachestat *cs;
+static struct cachestat_range *cs_range;
+
+static void test_cached_pages(const int num_pages)
+{
+	int fd, file_size;
+
+	tst_res(TINFO, "Number of pages: %d", num_pages);
+
+	memset(cs, 0, sizeof(struct cachestat));
+
+	fd = shm_open(FILENAME, O_RDWR | O_CREAT, 0600);
+	if (fd < 0)
+		tst_brk(TBROK | TERRNO, "shm_open error");
+
+	file_size = page_size * num_pages;
+
+	cs_range->off = 0;
+	cs_range->len = file_size;
+
+	SAFE_FTRUNCATE(fd, file_size);
+	for (int i = 0; i < num_pages; i++)
+		SAFE_WRITE(0, fd, page_data, page_size);
+
+	TST_EXP_PASS(cachestat(fd, cs_range, cs, 0));
+	print_cachestat(cs);
+
+	TST_EXP_EQ_LI(cs->nr_cache + cs->nr_evicted, num_pages);
+
+	SAFE_CLOSE(fd);
+	shm_unlink(FILENAME);
+}
+
+static void run(void)
+{
+	for (int i = 0; i < 10; i++)
+		test_cached_pages(1 << i);
+}
+
+static void setup(void)
+{
+	page_size = (int)sysconf(_SC_PAGESIZE);
+
+	page_data = SAFE_MALLOC(page_size);
+	memset(page_data, 'a', page_size);
+}
+
+static void cleanup(void)
+{
+	if (page_data)
+		free(page_data);
+}
+
+static struct tst_test test = {
+	.test_all = run,
+	.setup = setup,
+	.cleanup = cleanup,
+	.needs_tmpdir = 1,
+	.min_kver = "6.5",
+	.bufs = (struct tst_buffers []) {
+		{&cs, .size = sizeof(struct cachestat)},
+		{&cs_range, .size = sizeof(struct cachestat_range)},
+		{}
+	},
+};

-- 
2.43.0