mm: use helper for calling f_op->mmap()

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a3145cd..93691b5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1727,6 +1727,11 @@ static inline ssize_t call_write_iter(struct file *file, struct kiocb *kio,
 	return file->f_op->write_iter(kio, iter);
 }
 
+static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return file->f_op->mmap(file, vma);
+}
+
 ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			      unsigned long nr_segs, unsigned long fast_segs,
 			      struct iovec *fast_pointer,