thp: vma_adjust_trans_huge(): adjust file-backed VMA too

This series of patches adds support for using PMD page table entries to
map DAX files. We expect NV-DIMMs to start showing up that are many
gigabytes in size and the memory consumption of 4kB PTEs will be
astronomical.

The patch series leverages much of the Transparant Huge Pages
infrastructure, going so far as to borrow one of Kirill's patches from
his THP page cache series.

This patch (of 10):

Since we're going to have huge pages in page cache, we need to call adjust
file-backed VMA, which potentially can contain huge pages.

For now we call it for all VMAs.

Probably later we will need to introduce a flag to indicate that the VMA
has huge pages.

Signed-off-by: Kirill A. Shutemov <[e-mail]>
Signed-off-by: Matthew Wilcox <[e-mail]>
Acked-by: Hillf Danton <[e-mail]>
Cc: Theodore Ts'o <[e-mail]>
Cc: Jan Kara <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/huge_mm.h

···
 #endif
 extern int hugepage_madvise(struct vm_area_struct *vma,
 			    unsigned long *vm_flags, int advice);
-extern void __vma_adjust_trans_huge(struct vm_area_struct *vma,
+extern void vma_adjust_trans_huge(struct vm_area_struct *vma,
 				    unsigned long start,
 				    unsigned long end,
 				    long adjust_next);
···
 		return __pmd_trans_huge_lock(pmd, vma, ptl);
 	else
 		return 0;
-}
-static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
-					 unsigned long start,
-					 unsigned long end,
-					 long adjust_next)
-{
-	if (!vma->anon_vma || vma->vm_ops)
-		return;
-	__vma_adjust_trans_huge(vma, start, end, adjust_next);
 }
 static inline int hpage_nr_pages(struct page *page)
 {

mm/huge_memory.c

···
 	split_huge_page_pmd_mm(mm, address, pmd);
 }
 
-void __vma_adjust_trans_huge(struct vm_area_struct *vma,
+void vma_adjust_trans_huge(struct vm_area_struct *vma,
 			     unsigned long start,
 			     unsigned long end,
 			     long adjust_next)