linux-kernel - [PATCH 3/8] mshare: selftests: Add some helper function for mshare filesystem

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Message-Id: <20250825145719.29455-4-linyongting@bytedance.com>
Date: Mon, 25 Aug 2025 22:57:06 +0800
From: Yongting Lin <linyongting@...edance.com>
To: anthony.yznaga@...cle.com,
	khalid@...nel.org,
	shuah@...nel.org,
	linyongting@...edance.com
Cc: linux-kernel@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	akpm@...ux-foundation.org,
	linux-mm@...ck.org
Subject: [PATCH 3/8] mshare: selftests: Add some helper function for mshare filesystem

Before create basic test cases, we need to have some helper functions
to help setup the tests.

These helper functions consist of:
  Mount and unmount the mshare filesystem
  Create a temporary file which be performed test on it later
  Map and unmap mshare region via the ioctl syscall

Signed-off-by: Yongting Lin <linyongting@...edance.com>
---
 tools/testing/selftests/mshare/basic.c |   1 +
 tools/testing/selftests/mshare/util.c  | 123 +++++++++++++++++++++++++
 2 files changed, 124 insertions(+)
 create mode 100644 tools/testing/selftests/mshare/util.c

diff --git a/tools/testing/selftests/mshare/basic.c b/tools/testing/selftests/mshare/basic.c
index 482af948878d..35739b1133f7 100644
--- a/tools/testing/selftests/mshare/basic.c
+++ b/tools/testing/selftests/mshare/basic.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include "../kselftest_harness.h"
+#include "util.c"
 
 TEST(basic)
 {
diff --git a/tools/testing/selftests/mshare/util.c b/tools/testing/selftests/mshare/util.c
new file mode 100644
index 000000000000..75f6ff25aa2c
--- /dev/null
+++ b/tools/testing/selftests/mshare/util.c
@@ -0,0 +1,123 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/msharefs.h>
+#include <stdio.h>
+#include <mntent.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+/*
+ *  Helper functions for mounting msharefs
+ */
+
+#define MOUNT_POINT "/sys/fs/mshare"
+#define FS_TYPE     "msharefs"
+
+bool is_msharefs_mounted(void)
+{
+	FILE *fp;
+	struct mntent *ent;
+	bool found = false;
+
+	fp = setmntent("/proc/mounts", "r");
+	if (!fp) {
+		perror("setmntent");
+		exit(1);
+	}
+
+	while ((ent = getmntent(fp)) != NULL) {
+		if (strcmp(ent->mnt_dir, MOUNT_POINT) == 0 &&
+			strcmp(ent->mnt_type, FS_TYPE) == 0) {
+			found = true;
+			break;
+		}
+	}
+
+	endmntent(fp);
+	return found;
+}
+
+bool msharefs_premounted;
+
+__attribute__((constructor))
+void mount_sharefs(void)
+{
+	msharefs_premounted = is_msharefs_mounted();
+	if (msharefs_premounted)
+		return;
+
+	if (mount(FS_TYPE, MOUNT_POINT, FS_TYPE, 0, NULL) != 0) {
+		perror("mount");
+		exit(1);
+	}
+}
+
+__attribute__((destructor))
+void umount_sharefs(void)
+{
+	if (!msharefs_premounted && umount(MOUNT_POINT) != 0) {
+		perror("umount");
+		exit(1);
+	}
+}
+
+/*
+ *  Helper functions for mshare files
+ */
+
+#define MSHARE_INFO MOUNT_POINT "/mshare_info"
+#define MSHARE_TEST MOUNT_POINT "/mshare-test-XXXXXX"
+
+size_t mshare_get_info(void)
+{
+	char req[128];
+	size_t size;
+	int fd;
+
+	fd = open(MSHARE_INFO, O_RDONLY);
+	if (fd == -1)
+		return -1;
+
+	read(fd, req, sizeof(req));
+	size = atoll(req);
+	close(fd);
+
+	return size;
+}
+
+int create_mshare_file(char *filename, size_t len)
+{
+	int fd;
+
+	strncpy(filename, MSHARE_TEST, len - 1);
+	fd = mkstemp(filename);
+
+	return fd;
+}
+
+
+int mshare_ioctl_mapping(int fd, size_t size, int flags)
+{
+	struct mshare_create mcreate;
+
+	mcreate.region_offset = 0;
+	mcreate.size = size;
+	mcreate.offset = 0;
+	mcreate.prot = PROT_READ | PROT_WRITE;
+	mcreate.flags = flags;
+	mcreate.fd = -1;
+
+	return ioctl(fd, MSHAREFS_CREATE_MAPPING, &mcreate);
+}
+
+int mshare_ioctl_munmap(int fd, size_t size)
+{
+	struct mshare_unmap munmap;
+
+	munmap.region_offset = 0;
+	munmap.size = size;
+
+	return ioctl(fd, MSHAREFS_UNMAP, &munmap);
+}
-- 
2.20.1