mm, hugetlbfs: rename address to haddr in hugetlb_cow()

To take better advantage of general huge page copying optimization, the
target subpage address will be passed to hugetlb_cow(), then
copy_user_huge_page().  So we will use both target subpage address and
huge page size aligned address in hugetlb_cow().  To distinguish between
them, "haddr" is used for huge page size aligned address to be
consistent with Transparent Huge Page naming convention.

Now, only huge page size aligned address is used in hugetlb_cow(), so
the "address" is renamed to "haddr" in hugetlb_cow() in this patch.
Next patch will use target subpage address in hugetlb_cow() too.

The patch is just code cleanup without any functionality changes.

Link: http://lkml.kernel.org/r/20180524005851.4079-4-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shaohua Li <shli@fb.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hugetlb.c

@@ -3509,7 +3509,7 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
  * Keep the pte_same checks anyway to make transition from the mutex easier.
  */
 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
-		       unsigned long address, pte_t *ptep,
+		       unsigned long haddr, pte_t *ptep,
 		       struct page *pagecache_page, spinlock_t *ptl)
 {
 	pte_t pte;
@@ -3527,7 +3527,7 @@ retry_avoidcopy:
 	 * and just make the page writable */
 	if (page_mapcount(old_page) == 1 && PageAnon(old_page)) {
 		page_move_anon_rmap(old_page, vma);
-		set_huge_ptep_writable(vma, address, ptep);
+		set_huge_ptep_writable(vma, haddr, ptep);
 		return 0;
 	}
 
@@ -3551,7 +3551,7 @@ retry_avoidcopy:
 	 * be acquired again before returning to the caller, as expected.
 	 */
 	spin_unlock(ptl);
-	new_page = alloc_huge_page(vma, address, outside_reserve);
+	new_page = alloc_huge_page(vma, haddr, outside_reserve);
 
 	if (IS_ERR(new_page)) {
 		/*
@@ -3564,11 +3564,10 @@ retry_avoidcopy:
 		if (outside_reserve) {
 			put_page(old_page);
 			BUG_ON(huge_pte_none(pte));
-			unmap_ref_private(mm, vma, old_page, address);
+			unmap_ref_private(mm, vma, old_page, haddr);
 			BUG_ON(huge_pte_none(pte));
 			spin_lock(ptl);
-			ptep = huge_pte_offset(mm, address & huge_page_mask(h),
-					       huge_page_size(h));
+			ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
 			if (likely(ptep &&
 				   pte_same(huge_ptep_get(ptep), pte)))
 				goto retry_avoidcopy;
@@ -3593,12 +3592,12 @@ retry_avoidcopy:
 		goto out_release_all;
 	}
 
-	copy_user_huge_page(new_page, old_page, address, vma,
+	copy_user_huge_page(new_page, old_page, haddr, vma,
 			    pages_per_huge_page(h));
 	__SetPageUptodate(new_page);
 	set_page_huge_active(new_page);
 
-	mmun_start = address & huge_page_mask(h);
+	mmun_start = haddr;
 	mmun_end = mmun_start + huge_page_size(h);
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 
@@ -3607,25 +3606,24 @@ retry_avoidcopy:
 	 * before the page tables are altered
 	 */
 	spin_lock(ptl);
-	ptep = huge_pte_offset(mm, address & huge_page_mask(h),
-			       huge_page_size(h));
+	ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
 	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
 		ClearPagePrivate(new_page);
 
 		/* Break COW */
-		huge_ptep_clear_flush(vma, address, ptep);
+		huge_ptep_clear_flush(vma, haddr, ptep);
 		mmu_notifier_invalidate_range(mm, mmun_start, mmun_end);
-		set_huge_pte_at(mm, address, ptep,
+		set_huge_pte_at(mm, haddr, ptep,
 				make_huge_pte(vma, new_page, 1));
 		page_remove_rmap(old_page, true);
-		hugepage_add_new_anon_rmap(new_page, vma, address);
+		hugepage_add_new_anon_rmap(new_page, vma, haddr);
 		/* Make the old page be freed below */
 		new_page = old_page;
 	}
 	spin_unlock(ptl);
 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 out_release_all:
-	restore_reserve_on_error(h, vma, address, new_page);
+	restore_reserve_on_error(h, vma, haddr, new_page);
 	put_page(new_page);
 out_release_old:
 	put_page(old_page);