Return-Path: Received: from mail-ed1-f50.google.com ([209.85.208.50]:45782 "EHLO mail-ed1-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729415AbeJAVKh (ORCPT ); Mon, 1 Oct 2018 17:10:37 -0400 MIME-Version: 1.0 From: Joshi Date: Mon, 1 Oct 2018 20:02:17 +0530 Message-ID: Subject: cross-fs copy support To: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-ext4-owner@vger.kernel.org List-ID: I was wondering about the cross-fs copy through copy_file_range. It seems current implement has below check, that disables such copy. 1577 /* this could be relaxed once a method supports cross-fs copies */ 1578 if (inode_in->i_sb != inode_out->i_sb) 1579 return -EXDEV; May I know what are the thoughts behind disabling cross-fs copy? Code has the comment "once a method supports", but that leaves me wondering exactly what 'method' is expected, and from whom. I disabled the check, and copy across volumes seemed to work fine. At least for a single file (1G size), with no data mismatch, and faster speed than regular copy. -- Joshi