Messages in this thread | | | Date | Thu, 26 Aug 2004 17:00:53 +0100 | From | Jamie Lokier <> | Subject | Re: silent semantic changes with reiser4 |
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Christophe Saout wrote: > I'm just thinking about something. While you can't cut bytes out of unix > iles a lot of filesystems can do this (holes). Most of them only on a > block boundary, reiser4 on a byte boundary. If the filesystems could > export this functionality using an enhanced API we could implement a > compression plugin and other things on the VFS level that works with > every filesystem supporting the required mechanisms, not only reiser4. > And those features would take advantage of reiser4's storage mechanisms. > I think Hans made the plugins reiser4-only because only reiser4 has a > similar API at that time (and obviously because he didn't even think > about doing it otherwise).
Yes. In some cases the compression or re-archiving algorithm would choose different parameters, depending on the alignment capabilities of the underlying filesystem. In some cases, that alignment is "offset 0 is the only one you can have", which is a severe special case where truncate and rewrite is required for changes.
> > By the way, can reiser4 share parts of files between different files? > > At the moment a file is exactly one object. But someone could write > another file plugin that spans a file across multiple objects, then yes, > multiple files could share parts.
Nice. That's useful for files which appear as themselves and also as part of a container.
And also for revision managed filesystems :)
-- Jamie
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