mm/hugetlb: use a folio in hugetlb_fault()

We can replace seven implicit calls to compound_head() with one by using
folio.

[akpm@linux-foundation.org: update comment, per Sidhartha]
Link: https://lkml.kernel.org/r/20230606062013.2947002-4-zhangpeng362@huawei.comSigned-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -6062,7 +6062,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	vm_fault_t ret;
 	u32 hash;
 	pgoff_t idx;
-	struct page *page = NULL;
+	struct folio *folio = NULL;
 	struct folio *pagecache_folio = NULL;
 	struct hstate *h = hstate_vma(vma);
 	struct address_space *mapping;
@@ -6179,16 +6179,16 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	/*
 	 * hugetlb_wp() requires page locks of pte_page(entry) and
 	 * pagecache_folio, so here we need take the former one
-	 * when page != pagecache_folio or !pagecache_folio.
+	 * when folio != pagecache_folio or !pagecache_folio.
 	 */
-	page = pte_page(entry);
-	if (page_folio(page) != pagecache_folio)
-		if (!trylock_page(page)) {
+	folio = page_folio(pte_page(entry));
+	if (folio != pagecache_folio)
+		if (!folio_trylock(folio)) {
 			need_wait_lock = 1;
 			goto out_ptl;
 		}
 
-	get_page(page);
+	folio_get(folio);
 
 	if (flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
 		if (!huge_pte_write(entry)) {
@@ -6204,9 +6204,9 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 						flags & FAULT_FLAG_WRITE))
 		update_mmu_cache(vma, haddr, ptep);
 out_put_page:
-	if (page_folio(page) != pagecache_folio)
-		unlock_page(page);
-	put_page(page);
+	if (folio != pagecache_folio)
+		folio_unlock(folio);
+	folio_put(folio);
 out_ptl:
 	spin_unlock(ptl);
 
@@ -6225,7 +6225,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * here without taking refcount.
 	 */
 	if (need_wait_lock)
-		wait_on_page_locked(page);
+		folio_wait_locked(folio);
 	return ret;
 }