On Thu, Jul 15, 2021 at 09:53:26PM +0800, kernel test robot wrote:
> >> fs/iomap/buffered-io.c:645:2: error: implicit declaration of function 'flush_dcache_folio' [-Werror,-Wimplicit-function-declaration]
>            flush_dcache_folio(folio);

Thanks.  ARM doesn't include asm-generic/cacheflush.h so it needs
flush_dcache_folio() declared.  Adding this:

+++ b/arch/arm/include/asm/cacheflush.h
@@ -290,6 +290,7 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr
  */
 #define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 1
 extern void flush_dcache_page(struct page *);
+void flush_dcache_folio(struct folio *folio);

 static inline void flush_kernel_vmap_range(void *addr, int size)
 {