[PATCH] fs: dax: fix build error on ARC

[Randy Dunlap <rdunlap@infradead.org>]

From: Randy Dunlap <rdunlap@infradead.org>

fs/dax.c uses copy_user_page() but ARC does not provide that interface,
resulting in a build error.

Provide copy_user_page() in <asm/page.h> (beside copy_page()) and
add <asm/page.h> to fs/dax.c to fix the build error.

../fs/dax.c: In function 'copy_cow_page_dax':
../fs/dax.c:702:2: error: implicit declaration of function 'copy_user_page'; did you mean 'copy_to_user_page'? [-Werror=implicit-function-declaration]

Fixes: cccbce671582 ("filesystem-dax: convert to dax_direct_access()")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: linux-snps-arc@lists.infradead.org
Cc: Dan Williams <dan.j.williams@intel.com>
---
Vineet, This patch fixes the build error but is it correct for ARC?

 arch/arc/include/asm/page.h |    1 +
 fs/dax.c                    |    1 +
 2 files changed, 2 insertions(+)

--- lnx-59-rc7.orig/fs/dax.c
+++ lnx-59-rc7/fs/dax.c
@@ -25,6 +25,7 @@
 #include <linux/sizes.h>
 #include <linux/mmu_notifier.h>
 #include <linux/iomap.h>
+#include <asm/page.h>
 #include <asm/pgalloc.h>
 
 #define CREATE_TRACE_POINTS
--- lnx-59-rc7.orig/arch/arc/include/asm/page.h
+++ lnx-59-rc7/arch/arc/include/asm/page.h
@@ -10,6 +10,7 @@
 #ifndef __ASSEMBLY__
 
 #define clear_page(paddr)		memset((paddr), 0, PAGE_SIZE)
+#define copy_user_page(to, from, vaddr, pg)	copy_page(to, from)
 #define copy_page(to, from)		memcpy((to), (from), PAGE_SIZE)
 
 struct vm_area_struct;