Re: New filesystem for Linux kernel

[hooanon05@yahoo.co.jp]

Miklos Szeredi:
> It's always easier to review something with less features, even if
> that feature set is too little for real world use.

Generally I agree with you.


> The simplest version is with all branches read-only.  That gets rid of
> a _huge_ amount of complexity, yet it's still useful in some
> situations.  It also deals with a lot of the basic infrastucture
> needed for stacking.

If you really think it is a better way to get merged into mainline, then
I'll try implement such version.


> And that's when one starts thinking about whether unioning is really
> the right solution.  Instead this could be implemented with a special
> filesystem format that only contains deltas to the data, metatata and
> directory tree.  It would be much more space efficient, could easily
> handle renames, hard links etc, without all the hacks that
> unionfs/aufs does.

It sounds like an ODF (on disk format) version of unionfs (while it
seems to be inactive).
At implementing, I don't think it easier to maintain delta of filedata
and metadata. Since aufs has a writable branch in it, it is better and
easier to maintain data in a branch fs.
If you think there should not be any writable branch in aufs, and all
"write" goes to a new filesystem format, then it is equivalent to a
writable branch, isn't it?
If you say "just a part of write" goes to a new fs, then I don't think
we can support several essential features, for instance mmap.


J. R. Okajima