mm/hugetlb: convert hugetlbfs_pagecache_present() to folios

Refactor hugetlbfs_pagecache_present() to avoid getting and dropping a
refcount on a page.  Use RCU and page_cache_next_miss() instead.

Link: https://lkml.kernel.org/r/20230125170537.96973-3-sidhartha.kumar@oracle.comSuggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -5651,17 +5651,15 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 static bool hugetlbfs_pagecache_present(struct hstate *h,
 			struct vm_area_struct *vma, unsigned long address)
 {
-	struct address_space *mapping;
-	pgoff_t idx;
-	struct page *page;
+	struct address_space *mapping = vma->vm_file->f_mapping;
+	pgoff_t idx = vma_hugecache_offset(h, vma, address);
+	bool present;
 
-	mapping = vma->vm_file->f_mapping;
-	idx = vma_hugecache_offset(h, vma, address);
+	rcu_read_lock();
+	present = page_cache_next_miss(mapping, idx, 1) != idx;
+	rcu_read_unlock();
 
-	page = find_get_page(mapping, idx);
-	if (page)
-		put_page(page);
-	return page != NULL;
+	return present;
 }
 
 int hugetlb_add_to_page_cache(struct page *page, struct address_space *mapping,