mm/huge_memory: make is_transparent_hugepage() static

It's only used inside the huge_memory.c now. Don't export it and make
it static. We can thus reduce the size of huge_memory.o a bit.

Without this patch:
   text	   data	    bss	    dec	    hex	filename
  32319	   2965	      4	  35288	   89d8	mm/huge_memory.o

With this patch:
   text	   data	    bss	    dec	    hex	filename
  32042	   2957	      4	  35003	   88bb	mm/huge_memory.o

Link: https://lkml.kernel.org/r/20220302082145.12028-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: MiaoheLin

include/linux/huge_mm.h

@@ -183,7 +183,6 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 
 void prep_transhuge_page(struct page *page);
 void free_transhuge_page(struct page *page);
-bool is_transparent_hugepage(struct page *page);
 
 bool can_split_folio(struct folio *folio, int *pextra_pins);
 int split_huge_page_to_list(struct page *page, struct list_head *list);
@@ -341,11 +340,6 @@ static inline bool transhuge_vma_enabled(struct vm_area_struct *vma,
 
 static inline void prep_transhuge_page(struct page *page) {}
 
-static inline bool is_transparent_hugepage(struct page *page)
-{
-	return false;
-}
-
 #define transparent_hugepage_flags 0UL
 
 #define thp_get_unmapped_area	NULL

mm/huge_memory.c

@@ -533,7 +533,7 @@ void prep_transhuge_page(struct page *page)
 	set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
 }
 
-bool is_transparent_hugepage(struct page *page)
+static inline bool is_transparent_hugepage(struct page *page)
 {
 	if (!PageCompound(page))
 		return false;
@@ -542,7 +542,6 @@ bool is_transparent_hugepage(struct page *page)
 	return is_huge_zero_page(page) ||
 	       page[1].compound_dtor == TRANSHUGE_PAGE_DTOR;
 }
-EXPORT_SYMBOL_GPL(is_transparent_hugepage);
 
 static unsigned long __thp_get_unmapped_area(struct file *filp,
 		unsigned long addr, unsigned long len,