mm/memory: convert do_page_mkwrite() to use folios

Saves one implicit call to compound_head().

Link: https://lkml.kernel.org/r/20230706163847.403202-1-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory.c

@@ -2933,7 +2933,7 @@ static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
 static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
 {
 	vm_fault_t ret;
-	struct page *page = vmf->page;
+	struct folio *folio = page_folio(vmf->page);
 	unsigned int old_flags = vmf->flags;
 
 	vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
@@ -2948,14 +2948,14 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
 	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
 		return ret;
 	if (unlikely(!(ret & VM_FAULT_LOCKED))) {
-		lock_page(page);
-		if (!page->mapping) {
-			unlock_page(page);
+		folio_lock(folio);
+		if (!folio->mapping) {
+			folio_unlock(folio);
 			return 0; /* retry */
 		}
 		ret |= VM_FAULT_LOCKED;
 	} else
-		VM_BUG_ON_PAGE(!PageLocked(page), page);
+		VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
 	return ret;
 }