sh/mm/cache: use folio_mapped() in copy_from_user_page()

We want to limit the use of page_mapcount() to the places where it is
absolutely necessary.

We're already using folio_mapped in copy_user_highpage() and
copy_to_user_page() for a similar purpose so ...  let's also simply use it
for copy_from_user_page().

There is no change for small folios.  Likely we won't stumble over many
large folios on sh in that code either way.

Link: https://lkml.kernel.org/r/20240409192301.907377-13-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Richard Chang <richardycc@google.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/sh/mm/cache.c

@@ -84,7 +84,7 @@ void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
 {
 	struct folio *folio = page_folio(page);
 
-	if (boot_cpu_data.dcache.n_aliases && page_mapcount(page) &&
+	if (boot_cpu_data.dcache.n_aliases && folio_mapped(folio) &&
 	    test_bit(PG_dcache_clean, &folio->flags)) {
 		void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
 		memcpy(dst, vfrom, len);