Re: silent semantic changes with reiser4
From: Hans Reiser
Date: Mon Aug 30 2004 - 14:08:04 EST
Alex Zarochentsev wrote:
On Thu, Aug 26, 2004 at 05:53:51PM +0100, Jamie Lokier wrote:
Rik van Riel wrote:
And if an unaware application reads the compound file
and then writes it out again, does the filesystem
interpret the contents and create the other streams ?
Yes, exactly that. The streams are created on demand of course, and
by userspace helpers when that's appropriate which I suspect it almost
always is.
Unless I overlook something (please tell me what), the
scheme just proposed requires filesystems to look at
the content of files that is being written out, in
order to make the streams work.
Yes. Hence the idea of coherent views between two files: writing to
one affects the content of the other, although the calcalation is only
done on demand (or when the fs wants to migrate the representation --
for example, creating the flat container prior to deleting the
regeneratable pieces in order to save space).
I haven't seen anything from Namesys that says they'll do that.
We do that, err, it is our design to do that. Hmm, the plugins to do
that seem to all be in the next to implement list and not on the
implemented already list.....
However, with respect to streams, those are just files in a
file-directory object in our scheme. If you want them unified, well,
then you cat compound-document/pseudos/glued, or you link
compound-document/pseudos/glued to compound-document/pseudos/body, where
body is our term for the default stream, and then you just cat
compound-document
If you have the impression I am being vaporwarish, well, you are
right.... glued is not yet on the already implemented list.
Hans
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