Date: Sun, 29 Jun 2003 13:19:24 -0700 (PDT)
From: Davide Libenzi <davidel@xmailserver.org>
To: viro@parcelfarce.linux.theplanet.co.uk
cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: File System conversion -- ideas
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On Sun, 29 Jun 2003 viro@parcelfarce.linux.theplanet.co.uk wrote:

> I think that I will believe it when I see the patchset implementing it.
> Provided that it will be convincing enough.  Other than that...  Not
> really.  You will need code for each pair of filesystems, since
> convertor will need to know *both* layouts.  No amount of handwaving
> is likely to work around that.  And we have what, something between
> 10 and 20 local filesystems?  Have fun...
>
> If you want your idea to be considered seriously - take reiserfs code,
> take ext3 code, copy both to userland and put together a conversion
> between them.  Both ways.  That, by definition, is easier than doing
> it in kernel - you have the same code available and none of the limitations/
> interaction with other stuff.  When you have it working, well, time to
> see what extra PITA will come from making it coexist with other parts
> of kernel (and with much more poor runtime environment).
>
> AFAICS, it is _very_ hard to implement.  Even outside of the kernel.
> If you can get it done - well, that might do a lot for having the
> idea considered seriously.  "Might" since you need to do it in a way
> that would survive transplantation into the kernel _and_ would scale
> better that O((number of filesystem types)^2).

Maybe defining a "neutral" metadata export/import might help in limiting
such NFS^2 ...


- Davide

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