diff --git a/mm/filemap.c b/mm/filemap.c
index a4a5260..51efee6 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1712,8 +1712,27 @@
 }
 EXPORT_SYMBOL(filemap_fault);
 
+int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	struct page *page = vmf->page;
+	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	int ret = VM_FAULT_LOCKED;
+
+	file_update_time(vma->vm_file);
+	lock_page(page);
+	if (page->mapping != inode->i_mapping) {
+		unlock_page(page);
+		ret = VM_FAULT_NOPAGE;
+		goto out;
+	}
+out:
+	return ret;
+}
+EXPORT_SYMBOL(filemap_page_mkwrite);
+
 const struct vm_operations_struct generic_file_vm_ops = {
 	.fault		= filemap_fault,
+	.page_mkwrite	= filemap_page_mkwrite,
 };
 
 /* This is used for a general mmap of a disk file */