Re: [CFD] disk format fixing

[Jiro SEKIBA <jir-hfpbi5WX9J54Eiagz67IpQ@public.gmane.org>]

Hi,

I'd like to summarize the comments so far for disk fomat fix.
Please correct it if it's wrong or missing something.


I've started this thread to fix disk format of nilfs2 at the point
everybody thinks it's ok, strip "experimental", encourage developing
user land tools and different implementation like on NetBSD.

So far, we have been talking disk format from two aspects,
spuer block and rest of disk.  That's simply because most of user land tools
care only super block and rest of disk are much more controversial
than super block.  I'd like to summarize from those aspects.

- Super block format

Super blocks are frequently updated hotspot of nilfs2.  This is not good
for low-end flash device for wearing point of view.  To address this problem,
suggested introducing new mount option that makes less updates super blocks.

At this point, super block format itself is unchanged, still oloder
nilfs implementation can find correct latest log in case of unclean mount.

- Rest of disk

* directory indexing
There is long term controversial discussion about directory indexing.
One is on memory indexing, the other is on disk indexing.  We have not
reached a resolution, but at least agreed "unchange for now".
So, disk format point of view, it'll be fixed for nilfs2.
However it is a subject to change for future nilfs2 or nilfs3 or so.

~~

There are more missing features that should be in a modern filesystem,
like xattr or posix acls, check ToDo list in following url:
http://www.nilfs.org/en/current_status.html

You may not have to know disk format but if you feel functions which 
are not in nilfs2, but mandatory to support, please state so.
Then we can start that the how those functions can be implmented in nilfs2
from disk format point of view.  Otherwise, any functions that requires disk
format change will be not supported in near future or forever "experimental".

thanks,

regards,
-- 
Jiro SEKIBA <jir-hfpbi5WX9J54Eiagz67IpQ@public.gmane.org>
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