configfs: Add unit tests

Signed-off-by: Bart Van Assche <bvanassche@acm.org>

fs/configfs/Kconfig

@@ -10,3 +10,11 @@ config CONFIGFS_FS
 
 	  Both sysfs and configfs can and should exist together on the
 	  same system. One is not a replacement for the other.
+
+config CONFIGFS_KUNIT_TEST
+	tristate "Configfs Kunit test" if !KUNIT_ALL_TESTS
+	depends on CONFIGFS_FS && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Run the configfs unit test at boot time. For more information, see
+	  also the Kunit documentation in Documentation/dev-tools/kunit/.

fs/configfs/Makefile

@@ -6,3 +6,5 @@
 obj-$(CONFIG_CONFIGFS_FS)	+= configfs.o
 
 configfs-objs	:= inode.o file.o dir.o symlink.o mount.o item.o
+
+obj-$(CONFIG_CONFIGFS_KUNIT_TEST) += configfs-test.o

fs/configfs/configfs-test.c

@@ -0,0 +1,132 @@
+#include <kunit/test.h>
+#include <linux/configfs.h>
+#include <linux/fs.h>
+#include <linux/uio.h>
+
+enum { ATTR_MAX_SIZE = 256 };
+
+struct configfs_test_item {
+	struct config_item item;
+	uint32_t nbytes;
+	char data[ATTR_MAX_SIZE];
+};
+
+static ssize_t bin_attr_read(struct config_item *item, void *buf, size_t len)
+{
+	struct configfs_test_item *ti = container_of(item, typeof(*ti), item);
+
+	memcpy(buf, ti->data, ti->nbytes);
+	return ti->nbytes;
+}
+
+static ssize_t bin_attr_write(struct config_item *item, const void *buf,
+			      size_t len)
+{
+	struct configfs_test_item *ti = container_of(item, typeof(*ti), item);
+
+	if (len > ATTR_MAX_SIZE)
+		return -EINVAL;
+	ti->nbytes = len;
+	memcpy(ti->data, buf, len);
+	return len;
+}
+
+CONFIGFS_BIN_ATTR(, bin_attr, NULL, ATTR_MAX_SIZE);
+
+static struct configfs_bin_attribute *bin_attrs[] = {
+	&attr_bin_attr,
+	NULL,
+};
+
+static ssize_t text_attr_show(struct config_item *item, char *buf)
+{
+	return bin_attr_read(item, buf, strlen(buf));
+}
+
+static ssize_t text_attr_store(struct config_item *item, const char *buf,
+			       size_t size)
+{
+	return bin_attr_write(item, buf, size);
+}
+
+CONFIGFS_ATTR(, text_attr);
+
+static struct configfs_attribute *text_attrs[] = {
+	&attr_text_attr,
+	NULL,
+};
+
+static const struct config_item_type test_configfs_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_bin_attrs = bin_attrs,
+	.ct_attrs = text_attrs,
+};
+
+static void configfs_text_attr(struct kunit *test)
+{
+	struct file *f = filp_open("/sys/kernel/config/unit-test/text_attr",
+				   O_RDWR, 0);
+	static const char text1[] =
+		"The quick brown fox jumps over the lazy dog";
+	const int off1 = 0;
+	const int len1 = strlen(text1);
+	static const char text2[] = "slow-";
+	const int off2 = 4;
+	const int len2 = strlen(text2);
+	int res;
+	loff_t pos;
+
+	KUNIT_EXPECT_TRUE(test, !IS_ERR(f));
+	if (IS_ERR(f))
+		return;
+	pos = off1;
+	res = kernel_write(f, text1, len1, &pos);
+	KUNIT_EXPECT_EQ(test, res, len1);
+	KUNIT_EXPECT_EQ(test, pos, off1 + len1);
+	pos = off2;
+	res = kernel_write(f, text2, len2, &pos);
+	KUNIT_EXPECT_EQ(test, res, len2);
+	KUNIT_EXPECT_EQ(test, pos, off2 + len2);
+	filp_close(f, NULL);
+}
+
+static void configfs_bin_attr(struct kunit *test)
+{
+	KUNIT_EXPECT_EQ(test, 0, 0);
+}
+
+static struct kunit_case configfs_test_cases[] = {
+	KUNIT_CASE(configfs_text_attr),
+	KUNIT_CASE(configfs_bin_attr),
+	{},
+};
+
+static struct configfs_subsystem test_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "unit-test",
+			.ci_type    = &test_configfs_type,
+		}
+	},
+};
+
+static int configfs_test_init(struct kunit *test)
+{
+	config_group_init(&test_subsys.su_group);
+	mutex_init(&test_subsys.su_mutex);
+	return configfs_register_subsystem(&test_subsys);
+}
+
+static void configfs_test_exit(struct kunit *test)
+{
+	configfs_unregister_subsystem(&test_subsys);
+}
+
+static struct kunit_suite configfs_test_module = {
+	.name		= "configfs unit tests",
+	.init		= configfs_test_init,
+	.exit		= configfs_test_exit,
+	.name		= "configfs-kunit-test",
+	.test_cases	= configfs_test_cases,
+};
+kunit_test_suites(&configfs_test_module);