mm/huge_memory: convert split_huge_pages_in_file() to use a folio

Patch series "Remove FGP_HEAD flag".

We have just two users left of the FGP_HEAD flag and both of them are
better off; sometimes startlingly so as a result of conversion to use
folios.


This patch (of 4):

Removes a number of calls to compound_head() and a call to
pagecache_get_page().

Link: https://lkml.kernel.org/r/20221019183332.2802139-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20221019183332.2802139-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/huge_memory.c

@@ -3066,28 +3066,28 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
 	mapping = candidate->f_mapping;
 
 	for (index = off_start; index < off_end; index += nr_pages) {
-		struct page *fpage = pagecache_get_page(mapping, index,
-						FGP_ENTRY | FGP_HEAD, 0);
+		struct folio *folio = __filemap_get_folio(mapping, index,
+						FGP_ENTRY, 0);
 
 		nr_pages = 1;
-		if (xa_is_value(fpage) || !fpage)
+		if (xa_is_value(folio) || !folio)
 			continue;
 
-		if (!is_transparent_hugepage(fpage))
+		if (!folio_test_large(folio))
 			goto next;
 
 		total++;
-		nr_pages = thp_nr_pages(fpage);
+		nr_pages = folio_nr_pages(folio);
 
-		if (!trylock_page(fpage))
+		if (!folio_trylock(folio))
 			goto next;
 
-		if (!split_huge_page(fpage))
+		if (!split_folio(folio))
 			split++;
 
-		unlock_page(fpage);
+		folio_unlock(folio);
 next:
-		put_page(fpage);
+		folio_put(folio);
 		cond_resched();
 	}