Revert "UBUNTU: SAUCE: mm/mmap: fix oopsing on remap_file_pages"

BugLink: http://bugs.launchpad.net/bugs/1558120

This reverts commit c7082994.

Revert in favor of slightly different upstream patch.
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

mm/mmap.c

@@ -2644,7 +2644,6 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	struct vm_area_struct *vma;
 	unsigned long populate = 0;
 	unsigned long ret = -EINVAL;
-	struct file *file;
 
 	pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
 			"See Documentation/vm/remap_file_pages.txt.\n",
@@ -2712,10 +2711,10 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 		}
 	}
 
-	file = get_file(vma->vm_file);
+	vma_get_file(vma);
 	ret = do_mmap_pgoff(vma->vm_file, start, size,
 			prot, flags, pgoff, &populate);
-	fput(file);
+	vma_fput(vma);
 out:
 	up_write(&mm->mmap_sem);
 	if (populate)