Re: reiser4 plugins

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Hans Reiser wrote:
Hubert Chan wrote:


On Tue, 05 Jul 2005 20:50:08 -0400 EDT, "Alexander G. M. Smith" <[email protected]> said:




That sounds equivalent to no hard links (other than the usual parent
directory one).  If there's any directory with two links to it, then
there will be a cycle somewhere!

What we want is no directed cycles.  That is A is the parent of B is the
parent of C is the parent of A.  We don't care about A is the parent of
B is the parent of C; A is the parent of B is the parent of C.

OK, here's a random idea that just popped into my head, and to which
I've given little thought (read: none whatsoever), and may be the
stupidest idea ever proposed on LKML, but thought I would just toss it
out to see if it could stimulate someone to come up with something
better (read: sane):  Conceptually, foo/.... is just a symlink to
/meta/[filesystem]/[inode of foo].



Except that we want the metafiles to go away when the base file goes away.

Only, /meta is a filesystem that already makes stuff go away for us, so all we have left is the issue of whether using /meta costs us performance, or whether breaking POSIX to add a symlink (such as foo/...) really gives us that much more usability.

I don't know the first thing about whether it costs us performance, although it seems like it could be negligable considering the existance of mount --bind.

I don't think file-as-dir gives us that much more usability, because we can always create a simple program or shell script that 'cd's us into metadata. It's still easier than having a simple program that manipulates the metadata directly, because this way we can do 'cd' and 'ls' and so on inside the metadata directory.

And, once we start talking about applications, /meta will be more readily supported (as in, some apps will go through a pathname and stop when they get to a file, and then there's tar). On apps which don't have direct support for /meta, you'd be navigating to the file in question and then manually typing '...' into the dialog, so I don't see why typing '...' at the end is better than typing '/meta' or '/meta/vfs' at the beginning.

That said, I'm still not entirely sure how we get /meta/vfs to work other than adding a '...' sort of delimiter anyway.

And a question: is it feasible to store, for each inode, its parent(s),
instead of just the hard link count?



Ooh, now that is an interesting old idea I haven't considered in 20
years.... makes fsck more robust too....

Doesn't it make directory operations slower, too?

And, will it require a format change?
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