userfaultfd: convert copy_huge_page_from_user() to copy_folio_from_user()

Replace copy_huge_page_from_user() with copy_folio_from_user(). 
copy_folio_from_user() does the same as copy_huge_page_from_user(), but
takes in a folio instead of a page.

Convert page_kaddr to kaddr in copy_folio_from_user() to do indenting
cleanup.

Link: https://lkml.kernel.org/r/20230410133932.32288-4-zhangpeng362@huawei.com
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm.h

@@ -3681,10 +3681,9 @@ extern void copy_user_huge_page(struct page *dst, struct page *src,
 				unsigned long addr_hint,
 				struct vm_area_struct *vma,
 				unsigned int pages_per_huge_page);
-extern long copy_huge_page_from_user(struct page *dst_page,
-				const void __user *usr_src,
-				unsigned int pages_per_huge_page,
-				bool allow_pagefault);
+long copy_folio_from_user(struct folio *dst_folio,
+			   const void __user *usr_src,
+			   bool allow_pagefault);
 
 /**
  * vma_is_special_huge - Are transhuge page-table entries considered special?

mm/hugetlb.c

@@ -6217,9 +6217,8 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
 			goto out;
 		}
 
-		ret = copy_huge_page_from_user(&folio->page,
-						(const void __user *) src_addr,
-						pages_per_huge_page(h), false);
+		ret = copy_folio_from_user(folio, (const void __user *) src_addr,
+					   false);
 
 		/* fallback to copy_from_user outside mmap_lock */
 		if (unlikely(ret)) {

mm/memory.c

@@ -5868,26 +5868,25 @@ void copy_user_huge_page(struct page *dst, struct page *src,
 	process_huge_page(addr_hint, pages_per_huge_page, copy_subpage, &arg);
 }
 
-long copy_huge_page_from_user(struct page *dst_page,
-				const void __user *usr_src,
-				unsigned int pages_per_huge_page,
-				bool allow_pagefault)
+long copy_folio_from_user(struct folio *dst_folio,
+			   const void __user *usr_src,
+			   bool allow_pagefault)
 {
-	void *page_kaddr;
+	void *kaddr;
 	unsigned long i, rc = 0;
-	unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
+	unsigned int nr_pages = folio_nr_pages(dst_folio);
+	unsigned long ret_val = nr_pages * PAGE_SIZE;
 	struct page *subpage;
 
-	for (i = 0; i < pages_per_huge_page; i++) {
-		subpage = nth_page(dst_page, i);
-		page_kaddr = kmap_local_page(subpage);
+	for (i = 0; i < nr_pages; i++) {
+		subpage = folio_page(dst_folio, i);
+		kaddr = kmap_local_page(subpage);
 		if (!allow_pagefault)
 			pagefault_disable();
-		rc = copy_from_user(page_kaddr,
-				usr_src + i * PAGE_SIZE, PAGE_SIZE);
+		rc = copy_from_user(kaddr, usr_src + i * PAGE_SIZE, PAGE_SIZE);
 		if (!allow_pagefault)
 			pagefault_enable();
-		kunmap_local(page_kaddr);
+		kunmap_local(kaddr);
 
 		ret_val -= (PAGE_SIZE - rc);
 		if (rc)

mm/userfaultfd.c

@@ -421,10 +421,8 @@ retry:
 			mmap_read_unlock(dst_mm);
 			BUG_ON(!page);
 
-			err = copy_huge_page_from_user(page,
-						(const void __user *)src_addr,
-						vma_hpagesize / PAGE_SIZE,
-						true);
+			err = copy_folio_from_user(page_folio(page),
+						   (const void __user *)src_addr, true);
 			if (unlikely(err)) {
 				err = -EFAULT;
 				goto out;