Re: Reiser4 DOS

[Nikita Danilov]

Michael Buesch writes:
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 > 
 > Hi,
 > 
 > I'm running linux-2.6.5 with latest reiser4 snapshot patch.
 > The following script makes my system completely
 > unresponsive in a short time.
 > 
 > #!/bin/sh
 > mount -treiser4 /dev/hdX /mnt/reiser4
 > cd /mnt/reiser4
 > while `/bin/true`; do
 >  cd metas
 > done

One can DoS any Linux file-system by

$ while : ;do mkdir x && cd x ;done

Due to some shell peculiarities (like doing getcwd() on each cd), it may
be necessary to re-write this in C. Problem is less grave on SMP system,
but it's only matter of running enough instances of this in parallel. :)

Nikita.

 > 
 > - -- 
 > Regards Michael Buesch  [ http://www.tuxsoft.de.vu ]
 > 
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Re: Reiser4 DOS

[Hans Reiser]

Markus Törnqvist wrote:

On Sun, May 02, 2004 at 03:38:47PM +0200, Michael Buesch wrote:
 

#!/bin/sh
mount -treiser4 /dev/hdX /mnt/reiser4
cd /mnt/reiser4
while `/bin/true`; do
	cd metas
done
   

Do I remember something of my own, or wasn't there some discussion about
this?
"Should meta files have meta files"

I'd say this is a bug, meta files seem like they shouldn't have meta
data, by definition.
 

Nikita

Is this going away in the next snapshot?

What about the metas dir inheriting +x from it's parent DIRECTORY, and
not necessarily parent FILE?
 

Re: Reiser4 DOS

[Markus Törnqvist]

On Sun, May 02, 2004 at 03:38:47PM +0200, Michael Buesch wrote:
>
>#!/bin/sh
>mount -treiser4 /dev/hdX /mnt/reiser4
>cd /mnt/reiser4
>while `/bin/true`; do
>   cd metas
>done

Do I remember something of my own, or wasn't there some discussion about
this?

"Should meta files have meta files"

I'd say this is a bug, meta files seem like they shouldn't have meta
data, by definition.

Is this going away in the next snapshot?

What about the metas dir inheriting +x from it's parent DIRECTORY, and
not necessarily parent FILE?

-- 
mjt

Re: Reiser4 DOS

[Michael Buesch]

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On Sunday 02 May 2004 15:54, you wrote:
> Are you sure this does not happen on other filesystem? This loop

No, I don't know another filesystem with some kind of these
meta-files and directories.

> mainly creates process creation pressure and is more likely some
> scheduler thing than Reiser4.
> 
> Maybe you can cure this using:
> 
> while : ; do
> ...

Same thing. Memory usage grows and grows until the
system is dead.

> 
> Sincerely yours,
>   René Rebe
> - ROCK Linux stable release maintainer

- -- 
Regards Michael Buesch  [ http://www.tuxsoft.de.vu ]


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