Re: [PATCH 2/3] md-cluster: introduce clear_clusterinfo_from_sb

[NeilBrown <neilb@suse.com>]

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On Fri, Nov 27 2015, Guoqing Jiang wrote:

> Hi Neil,
>
> On 11/27/2015 01:42 PM, NeilBrown wrote:
>> On Fri, Nov 20 2015, Guoqing Jiang <gqjiang@suse.com> wrote:
>>
>>> To change the bitmap from clustered to none, we also
>>> need to clean related info about cluster from sb, such
>>> as version, nodes and cluster_name.
>> I've applied the other two (though I removed the __func__ and __LINE__
>>  From error messages - they are just noise: the source of the message can
>> easily be found with out them - I should remove all the others).
>>
>> However I haven't applied this because there doesn't seem to be any
>> point.
>> Once your told that main md superblock that there is no bitmap, it
>> doesn't really matter what data is in the superblock of that
>> non-existent bitmap - it will never be looked at.  Will it?
> mdadm could still get nodes and cluster_name after change
> bitmap to none, so some cmds like "mdadm -X /dev/sda" could
> still see clustered info, it seems a little confused for user.

In that case we should fix mdadm to not report a bitmap if
MD_FEATURE_BITMAP_OFFSET isn't set (though maybe still report it if
--force is given).

i.e. if this is an issue, it is not specific to clustered-bitmaps.

NeilBrown

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