[LTP] [PATCH v8 4/4] Hugetlb: Migrating libhugetlbfs corrupt-by-cow-opt

[Tarun Sahu]

Migrating the libhugetlbfs/testcases/corrupt-by-cow-opt.c test

Test Description: Test sanity of cow optimization on page cache. If a page
in page cache has only 1 ref count, it is mapped for a private mapping
directly and is overwritten freely, so next time we access the page, we
can see corrupt data.

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
---
 runtest/hugetlb                               |  1 +
 testcases/kernel/mem/.gitignore               |  1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap09.c  | 79 +++++++++++++++++++
 3 files changed, 81 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 664f18827..e2ada7a97 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -5,6 +5,7 @@ hugemmap05 hugemmap05
 hugemmap06 hugemmap06
 hugemmap07 hugemmap07
 hugemmap08 hugemmap08
+hugemmap09 hugemmap09
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index 003ce422b..1a242ffe0 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -6,6 +6,7 @@
 /hugetlb/hugemmap/hugemmap06
 /hugetlb/hugemmap/hugemmap07
 /hugetlb/hugemmap/hugemmap08
+/hugetlb/hugemmap/hugemmap09
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c
new file mode 100644
index 000000000..1008395a4
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap09.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/*
+ * Copyright (C) 2013 Joonsoo Kim, LG Electronics.
+ * Author: Joonsoo Kim
+ */
+
+/*\
+ * [Description]
+ *
+ * Test sanity of cow optimization on page cache. If a page in page cache
+ * has only 1 ref count, it is mapped for a private mapping directly and
+ * is overwritten freely, so next time we access the page, we can see
+ * corrupt data.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <sys/mount.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <sys/types.h>
+
+#include "hugetlb.h"
+
+#define MNTPOINT "hugetlbfs/"
+static long hpage_size;
+static int huge_fd = -1;
+
+static void run_test(void)
+{
+	char *p;
+	char c;
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+			huge_fd, 0);
+	*p = 's';
+	tst_res(TINFO, "Write %c to %p via shared mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+			huge_fd, 0);
+	*p = 'p';
+	tst_res(TINFO, "Write %c to %p via private mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+			huge_fd, 0);
+	c = *p;
+	tst_res(TINFO, "Read %c from %p via shared mapping", *p, p);
+	SAFE_MUNMAP(p, hpage_size);
+
+	/* Direct write from huge page */
+	if (c != 's')
+		tst_res(TFAIL, "Data got corrupted.");
+	else
+		tst_res(TPASS, "Successful");
+}
+
+static void setup(void)
+{
+	hpage_size = SAFE_READ_MEMINFO(MEMINFO_HPAGE_SIZE)*1024;
+	huge_fd = tst_creat_unlinked(MNTPOINT);
+}
+
+static void cleanup(void)
+{
+	SAFE_CLOSE(huge_fd);
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+	.hugepages = {2, TST_NEEDS},
+};
-- 
2.31.1