mm: remove FGP_HEAD

This is no longer used; all callers have been converted to use folios
instead.  Somehow this manages to save 11 bytes of text.

Link: https://lkml.kernel.org/r/20221019183332.2802139-5-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/pagemap.h

@@ -504,9 +504,8 @@ pgoff_t page_cache_prev_miss(struct address_space *mapping,
 #define FGP_NOFS		0x00000010
 #define FGP_NOWAIT		0x00000020
 #define FGP_FOR_MMAP		0x00000040
-#define FGP_HEAD		0x00000080
-#define FGP_ENTRY		0x00000100
-#define FGP_STABLE		0x00000200
+#define FGP_ENTRY		0x00000080
+#define FGP_STABLE		0x00000100
 
 struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 		int fgp_flags, gfp_t gfp);

mm/folio-compat.c

@@ -108,7 +108,7 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
 	struct folio *folio;
 
 	folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
-	if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio))
+	if (!folio || xa_is_value(folio))
 		return &folio->page;
 	return folio_file_page(folio, index);
 }