huge tmpfs: move shmem_huge_enabled() upwards

shmem_huge_enabled() is about to be enhanced into shmem_is_huge(), so that
it can be used more widely throughout: before making functional changes,
shift it to its final position (to avoid forward declaration).

Link: https://lkml.kernel.org/r/16fec7b7-5c84-415a-8586-69d8bf6a6685@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Author: Hugh Dickins

mm/shmem.c

@@ -473,6 +473,41 @@ static bool shmem_confirm_swap(struct address_space *mapping,
 
 static int shmem_huge __read_mostly;
 
+bool shmem_huge_enabled(struct vm_area_struct *vma)
+{
+	struct inode *inode = file_inode(vma->vm_file);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+	loff_t i_size;
+	pgoff_t off;
+
+	if ((vma->vm_flags & VM_NOHUGEPAGE) ||
+	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
+		return false;
+	if (shmem_huge == SHMEM_HUGE_FORCE)
+		return true;
+	if (shmem_huge == SHMEM_HUGE_DENY)
+		return false;
+	switch (sbinfo->huge) {
+	case SHMEM_HUGE_NEVER:
+		return false;
+	case SHMEM_HUGE_ALWAYS:
+		return true;
+	case SHMEM_HUGE_WITHIN_SIZE:
+		off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
+		i_size = round_up(i_size_read(inode), PAGE_SIZE);
+		if (i_size >= HPAGE_PMD_SIZE &&
+				i_size >> PAGE_SHIFT >= off)
+			return true;
+		fallthrough;
+	case SHMEM_HUGE_ADVISE:
+		/* TODO: implement fadvise() hints */
+		return (vma->vm_flags & VM_HUGEPAGE);
+	default:
+		VM_BUG_ON(1);
+		return false;
+	}
+}
+
 #if defined(CONFIG_SYSFS)
 static int shmem_parse_huge(const char *str)
 {
@@ -3979,43 +4014,6 @@ struct kobj_attribute shmem_enabled_attr =
 	__ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-bool shmem_huge_enabled(struct vm_area_struct *vma)
-{
-	struct inode *inode = file_inode(vma->vm_file);
-	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
-	loff_t i_size;
-	pgoff_t off;
-
-	if ((vma->vm_flags & VM_NOHUGEPAGE) ||
-	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
-		return false;
-	if (shmem_huge == SHMEM_HUGE_FORCE)
-		return true;
-	if (shmem_huge == SHMEM_HUGE_DENY)
-		return false;
-	switch (sbinfo->huge) {
-		case SHMEM_HUGE_NEVER:
-			return false;
-		case SHMEM_HUGE_ALWAYS:
-			return true;
-		case SHMEM_HUGE_WITHIN_SIZE:
-			off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
-			i_size = round_up(i_size_read(inode), PAGE_SIZE);
-			if (i_size >= HPAGE_PMD_SIZE &&
-					i_size >> PAGE_SHIFT >= off)
-				return true;
-			fallthrough;
-		case SHMEM_HUGE_ADVISE:
-			/* TODO: implement fadvise() hints */
-			return (vma->vm_flags & VM_HUGEPAGE);
-		default:
-			VM_BUG_ON(1);
-			return false;
-	}
-}
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-
 #else /* !CONFIG_SHMEM */
 
 /*