From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:1905 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750903AbaLESnv (ORCPT ); Fri, 5 Dec 2014 13:43:51 -0500 Date: Fri, 5 Dec 2014 13:43:35 -0500 From: Chris Mason Subject: Re: [RFC][PATCH v2] mount.btrfs helper To: CC: , Dimitri John Ledkov , cwillu , linux-btrfs , Zygo Blaxell Message-ID: <1417805015.4845.0@mail.thefacebook.com> In-Reply-To: <5481F657.8090307@inwind.it> References: <547B5724.1060507@libero.it> <1417793566.21214.11@mail.thefacebook.com> <20141205164144.GK9754@suse.cz> <5481F657.8090307@inwind.it> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Dec 5, 2014 at 1:15 PM, Goffredo Baroncelli wrote: > On 12/05/2014 05:41 PM, David Sterba wrote: >> We're looking >> for good reasons to justify the existence of the helper, but this is >> still not enough IMHO. I can see the convenience to do it >> automatically, >> but this assumes no udev available which is probably rare these >> days. > > I have the following reasons to support a mount.btrfs helper: > 1) it is in a good point to check that everything is ok (see the > thread > related LVM snapshot, due to a dev.uuid conflicts), > 2) it is in a good point to issue a good error explanation (missing > device....) > 3) it may handle case like "degraded" mode, where the filesystem is > not > fully functional but even as degraded have "some" functionals.. Ok, these three things are worth improving, but I'd like to take a slightly different direction. Instead of recreating chunks of btrfs dev scan, lets extend btrfs dev scan to at the very least understand #1 and #2. As much as possible we want to be leveraging the data in udev instead of recreating that functionality. #3 is a slightly different feature, but we can have an extended btrfs dev scan or show explain the state of the filesystem to you. From there if we really need a mount helper, it can either use a libbtrfs to hit the scan code or be a bash script. Thanks for trying to smooth our or wrinkles in this area. It's definitely worth working on, I just want to make sure we recreate as little infrastructure as possible ;) -chris