Re: [PATCH 0/8] Introduce offline fsid/chunk tree uuid change for btrfstune.

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message  --------
Subject: Re: [PATCH 0/8] Introduce offline fsid/chunk tree uuid change 
for btrfstune.
From: Anand Jain <Anand.Jain@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>, <dsterba@suse.cz>
Date: 2015年05月12日 12:00

>
>
> On 05/12/2015 10:09 AM, Qu Wenruo wrote:
>>
>>
>> -------- Original Message  --------
>> Subject: Re: [PATCH 0/8] Introduce offline fsid/chunk tree uuid change
>> for btrfstune.
>> From: David Sterba <dsterba@suse.cz>
>> To: Qu Wenruo <quwenruo@cn.fujitsu.com>
>> Date: 2015年05月12日 00:24
>>
>>> On Fri, May 08, 2015 at 04:57:14PM +0800, Qu Wenruo wrote:
>>>>> Respecting the current syntax, the way to set the uuid is:
>>>>>
>>>>>    btrfs prop set -t filesytem /dev/sdx uuid ...UUID...
>>>>>
>>>>> In this special case, the property handler should check if the
>>>>> device is
>>>>> unmounted (and is a btrfs filesystem) and then do the rest.
>>>> This is one good idea, but I'm afraid it may still be confusing.
>>>> And things may get even worse when we try to move everything into
>>>> btrfs-prop,
>>>> E.g. if we auto move seeding flag to prop, we must give a quite
>>>> detailed
>>>> explain on which property is offline.
>>>>
>>>> So I prefer to add a new type called offline, and put uuid change with
>>>> other btrfstune function into this type.
>>>> IMHO this should provide a good explain on which is online and which is
>>>> offline.
>>>>
>>>> How do you think about this method?
>>>
>>> I don't think that 'offline' is a good choice. The type should denote
>>> the modified object, ie device, inode, filesystem. What's 'offline' in
>>> this context?
>> Right, 'offline' type here is just a easy trick for me to code, not a
>> meaningful type.
>>>
>>> The property interface can be used to modify other features both for
>>> mounted and unmounted filesystem, I agree that this should be done in a
>>> way that's not confusing. There are operations that are allowed on an
>>> unmounted fs (seeding), mounted + unmounted (extref feature) etc. so I
>>> think we could add options like --check-unmounted that would not allow
>>> to act on a mounted filesystem.
>>
>> Nice idea, but i prefer a option like "--offline" to enable the usage of
>> offline operations.
>> E.g, for normal online operations, nothing is changed.
>>
>> And for "btrfs prop set <DEV> uuid <UUID>", "--offline" must be
>> specified to work.
>> Or a message will be output to info user.
>>
>> What about this one?
>
>
> Qu, Thanks for the feature.
>
> Qu/David,
>
>   I strongly recommend this feature to be part of btrfstune as
>   of now, as originally planned by Qu. When its time to move
>   to btrfs cli we could. If we do it wrongly now it would stay
>   there forever.
>
>   We could take better call, when all the features of progs are
>   in place.
>
> Thanks, Anand
This is much easier for me, no need to consider the format of new 
online-offline mixed parameter for btrfs progs.

But the decision is on David.

Thanks,
Qu
>
>> Thanks,
>> Qu
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