Re: [PATCH v2 0/7] btrfs-progs: Support for BG_TREE feature

Qu Wenruo
2019-10-15T00:32:45Z

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On 2019/10/14 下午11:17, David Sterba wrote:
> On Tue, Oct 08, 2019 at 12:49:29PM +0800, Qu Wenruo wrote:
>> This patchset can be fetched from github:
>> https://github.com/adam900710/btrfs-progs/tree/bg_tree
>> Which is based on v5.2.2 tag.
>>
>> This patchset provides the needed user space infrastructure for BG_TREE
>> feature.
>>
>> Since it's an new incompatible feature, unlike SKINNY_METADATA, btrfs-progs
>> is needed to convert existing fs (unmounted) to new format.
>>
>> Now btrfstune can convert regular extent tree fs to bg tree fs to
>> improve mount time.
>
> Have we settled the argument whether to use a new tree or key tricks for
> the blocgroup data? I think we have not and will read the previous
> discussions. For a feature like this I want to be sure we understand all
> the pros and cons.
>
Yep, we haven't settled on the whether creating a new tree, or
re-organize the keys.

But as my last discussion said, I see no obvious pro using the existing
extent tree to hold the new block group item keys, even we can pack them
all together.

And for backup roots, indeed I forgot to add this feature.
But to me that's a minor point, not a show stopper.

The most important aspect to me is, to allow real world user of super
large fs to try this feature, to prove the usefulness of this design,
other than my on-paper analyse.

That's why I'm pushing the patchset, even it may not pass any review.
I just want to hold a up-to-date branch so that when some one needs, it
can grab and try them themselves.

Thanks,
Qu

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