smb/client: make SMB2 maperror KUnit tests a separate module

Build the SMB2 maperror KUnit tests as `smb2maperror_test.ko`.

Link: https://lore.kernel.org/linux-cifs/20260210081040.4156383-1-geert@linux-m68k.org/
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: ChenXiaoSong

fs/smb/client/Makefile

@@ -56,4 +56,6 @@ $(obj)/smb2maperror.o: $(obj)/smb2_mapping_table.c
 quiet_cmd_gen_smb2_mapping = GEN     $@
       cmd_gen_smb2_mapping = perl $(src)/gen_smb2_mapping $< $@
 
+obj-$(CONFIG_SMB_KUNIT_TESTS) += smb2maperror_test.o
+
 clean-files	+= smb2_mapping_table.c

fs/smb/client/smb2glob.h

@@ -46,4 +46,16 @@ enum smb2_compound_ops {
 #define END_OF_CHAIN 4
 #define RELATED_REQUEST 8
 
+/*
+ *****************************************************************
+ * Struct definitions go here
+ *****************************************************************
+ */
+
+struct status_to_posix_error {
+	__u32 smb2_status;
+	int posix_error;
+	char *status_string;
+};
+
 #endif	/* _SMB2_GLOB_H */

fs/smb/client/smb2maperror.c

@@ -8,20 +8,13 @@
  *
  */
 #include <linux/errno.h>
-#include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifs_debug.h"
 #include "smb2proto.h"
 #include "smb2glob.h"
 #include "../common/smb2status.h"
 #include "trace.h"
 
-struct status_to_posix_error {
-	__u32 smb2_status;
-	int posix_error;
-	char *status_string;
-};
-
 static const struct status_to_posix_error smb2_error_map_table[] = {
 /*
  * Automatically generated by the `gen_smb2_mapping` script,
@@ -115,10 +108,19 @@ int __init smb2_init_maperror(void)
 	return 0;
 }
 
-#define SMB_CLIENT_KUNIT_AVAILABLE \
-	((IS_MODULE(CONFIG_CIFS) && IS_ENABLED(CONFIG_KUNIT)) || \
-	 (IS_BUILTIN(CONFIG_CIFS) && IS_BUILTIN(CONFIG_KUNIT)))
+#if IS_ENABLED(CONFIG_SMB_KUNIT_TESTS)
+/* Previous prototype for eliminating the build warning. */
+const struct status_to_posix_error *smb2_get_err_map_test(__u32 smb2_status);
+
+const struct status_to_posix_error *smb2_get_err_map_test(__u32 smb2_status)
+{
+	return smb2_get_err_map(smb2_status);
+}
+EXPORT_SYMBOL_GPL(smb2_get_err_map_test);
+
+const struct status_to_posix_error *smb2_error_map_table_test = smb2_error_map_table;
+EXPORT_SYMBOL_GPL(smb2_error_map_table_test);
 
-#if SMB_CLIENT_KUNIT_AVAILABLE && IS_ENABLED(CONFIG_SMB_KUNIT_TESTS)
-#include "smb2maperror_test.c"
-#endif /* CONFIG_SMB_KUNIT_TESTS */
+unsigned int smb2_error_map_num = ARRAY_SIZE(smb2_error_map_table);
+EXPORT_SYMBOL_GPL(smb2_error_map_num);
+#endif

fs/smb/client/smb2maperror_test.c

@@ -9,13 +9,18 @@
  */
 
 #include <kunit/test.h>
+#include "smb2glob.h"
+
+const struct status_to_posix_error *smb2_get_err_map_test(__u32 smb2_status);
+extern const struct status_to_posix_error *smb2_error_map_table_test;
+extern unsigned int smb2_error_map_num;
 
 static void
 test_cmp_map(struct kunit *test, const struct status_to_posix_error *expect)
 {
 	const struct status_to_posix_error *result;
 
-	result = smb2_get_err_map(expect->smb2_status);
+	result = smb2_get_err_map_test(expect->smb2_status);
 	KUNIT_EXPECT_PTR_NE(test, NULL, result);
 	KUNIT_EXPECT_EQ(test, expect->smb2_status, result->smb2_status);
 	KUNIT_EXPECT_EQ(test, expect->posix_error, result->posix_error);
@@ -26,8 +31,8 @@ static void maperror_test_check_search(struct kunit *test)
 {
 	unsigned int i;
 
-	for (i = 0; i < ARRAY_SIZE(smb2_error_map_table); i++)
-		test_cmp_map(test, &smb2_error_map_table[i]);
+	for (i = 0; i < smb2_error_map_num; i++)
+		test_cmp_map(test, &smb2_error_map_table_test[i]);
 }
 
 static struct kunit_case maperror_test_cases[] = {
@@ -43,3 +48,4 @@ static struct kunit_suite maperror_suite = {
 kunit_test_suite(maperror_suite);
 
 MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("KUnit tests of SMB2 maperror");