Subject: Re: cp(1) vs. UVM/UBC
To: Matthias Scheler <tron@zhadum.de>
From: Ignatios Souvatzis <ignatios@theory.cs.uni-bonn.de>
List: tech-userlevel
Date: 07/19/2001 10:52:29
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On Thu, Jul 19, 2001 at 10:44:03AM +0200, Matthias Scheler wrote:
> On Thu, Jul 19, 2001 at 10:40:53AM +0200, Ignatios Souvatzis wrote:
> > There are other file systems with potential problems, if I recall right=
...
> > e.g., the DOS\0 and DOS\1 variants of adosfs, which always have some=20
> > metadata in their datablocks,
>=20
> It's DOS\0, DOS\2 and DOS\4 which have metadata in the data blocks.
>=20
> > ... so for this case, data copying always happens. (Chuck?)
>=20
> Does mmap() do that transperantly?

I don't remember ... that's why I wronte ``(Chuck?)'' above ('twas his code
that fixed DOS\0, only my alpha-testing). I might be able to just try one of
the next evenings. (Did I mention that I hate moving?)

> > Maybe we need to disable mmap()ing for such filesystems inside the kern=
el,
> > and make cp do the right thing if mmap fails? Is this possible?
>=20
> Sounds reasonable for "cp". But what about other applications?

Well, mmap() can always fail due to resource shortage, right? So an
application has to deal with it or fail in this case...

Regards,
	-is

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