mm: introduce fault_env

The idea borrowed from Peter's patch from patchset on speculative page
faults[1]:

Instead of passing around the endless list of function arguments,
replace the lot with a single structure so we can change context without
endless function signature changes.

The changes are mostly mechanical with exception of faultaround code:
filemap_map_pages() got reworked a bit.

This patch is preparation for the next one.

[1] http://lkml.kernel.org/r/20141020222841.302891540@infradead.org

Link: http://lkml.kernel.org/r/1466021202-61880-9-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f0a7a03..9bed924 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -1,20 +1,12 @@
 #ifndef _LINUX_HUGE_MM_H
 #define _LINUX_HUGE_MM_H
 
-extern int do_huge_pmd_anonymous_page(struct mm_struct *mm,
-				      struct vm_area_struct *vma,
-				      unsigned long address, pmd_t *pmd,
-				      unsigned int flags);
+extern int do_huge_pmd_anonymous_page(struct fault_env *fe);
 extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 			 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 			 struct vm_area_struct *vma);
-extern void huge_pmd_set_accessed(struct mm_struct *mm,
-				  struct vm_area_struct *vma,
-				  unsigned long address, pmd_t *pmd,
-				  pmd_t orig_pmd, int dirty);
-extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
-			       unsigned long address, pmd_t *pmd,
-			       pmd_t orig_pmd);
+extern void huge_pmd_set_accessed(struct fault_env *fe, pmd_t orig_pmd);
+extern int do_huge_pmd_wp_page(struct fault_env *fe, pmd_t orig_pmd);
 extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 					  unsigned long addr,
 					  pmd_t *pmd,
@@ -134,8 +126,7 @@
 	return 1;
 }
 
-extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
-				unsigned long addr, pmd_t pmd, pmd_t *pmdp);
+extern int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t orig_pmd);
 
 extern struct page *huge_zero_page;
 
@@ -196,8 +187,7 @@
 	return NULL;
 }
 
-static inline int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
-					unsigned long addr, pmd_t pmd, pmd_t *pmdp)
+static inline int do_huge_pmd_numa_page(struct fault_env *fe, pmd_t orig_pmd)
 {
 	return 0;
 }