From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:41909 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750957AbbIRGqs (ORCPT ); Fri, 18 Sep 2015 02:46:48 -0400 Message-ID: <55FBB2F7.4040402@oracle.com> Date: Fri, 18 Sep 2015 14:45:11 +0800 From: Anand Jain MIME-Version: 1.0 To: Qu Wenruo , Qu Wenruo , linux-btrfs@vger.kernel.org Subject: Re: [PATCH 2/2] btrfs: Remove unneeded missing device number check References: <1442375031-18212-1-git-send-email-quwenruo@cn.fujitsu.com> <1442375031-18212-2-git-send-email-quwenruo@cn.fujitsu.com> <55FA8B31.9080604@oracle.com> <55FA8F8B.6060903@gmx.com> <55FB6D31.9030504@oracle.com> <55FB71A8.3000004@cn.fujitsu.com> In-Reply-To: <55FB71A8.3000004@cn.fujitsu.com> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi Qu, Thanks for the comments on patch [1]. > For example, if one use single metadata for 2 disks, > and each disk has one metadata chunk on it. how that can be achieved ? > One device got missing later. it would surely depend on which one of the device ? (initial only devid 1 mountable, with other missing) Thanks, Anand > Then your patch will allow the fs to be mounted as rw, even some tree > block can be in the missing device. > For RO case, it won't be too dangerous, but if we mounted it as RW, who > knows what will happen. > (Normal tree COW thing should fail before real write, but I'm not sure > about other RW operation like scrub/replace/balance and others) > > And I think that's the original design concept behind the old missing > device number check, and it's not a bad idea to follow it anyway. > > For the patch size, I find a good idea to handle it, and should make the > patch(set) size below 200 lines. > > Further more, it's even possible to make btrfs change mount option to > degraded for runtime device missing. > > Thanks, > Qu >> >> I tried to break both the approaches (this patch set and [1]) but I >> wasn't successful. sorry if I am missing something. >> >> Thanks, Anand >> >> [1] [PATCH 23/23] Btrfs: allow -o rw,degraded for single group profile