kasan: only define metadata structs for Generic mode

Hide the definitions of kasan_alloc_meta and kasan_free_meta under an
ifdef CONFIG_KASAN_GENERIC check, as these structures are now only used
when the Generic mode is enabled.

Link: https://lkml.kernel.org/r/8d2aabff8c227c444a3f62edf87d5630beb77640.1662411799.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kasan/kasan.h

@@ -193,14 +193,12 @@ struct kasan_track {
 	depot_stack_handle_t stack;
 };
 
+#ifdef CONFIG_KASAN_GENERIC
+
 struct kasan_alloc_meta {
 	struct kasan_track alloc_track;
-	/* Generic mode stores free track in kasan_free_meta. */
-#ifdef CONFIG_KASAN_GENERIC
+	/* Free track is stored in kasan_free_meta. */
 	depot_stack_handle_t aux_stack[2];
-#else
-	struct kasan_track free_track;
-#endif
 };
 
 struct qlist_node {
@@ -219,12 +217,12 @@ struct qlist_node {
  * After that, slab allocator stores the freelist pointer in the object.
  */
 struct kasan_free_meta {
-#ifdef CONFIG_KASAN_GENERIC
 	struct qlist_node quarantine_link;
 	struct kasan_track free_track;
-#endif
 };
 
+#endif /* CONFIG_KASAN_GENERIC */
+
 #if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
 /* Used in KUnit-compatible KASAN tests. */
 struct kunit_kasan_status {