Re: reiser4 plugins

From: Artem B. Bityuckiy
Date: Mon Jun 27 2005 - 02:31:25 EST


Valdis.Kletnieks@xxxxxx wrote:
For more fun, consider how you can write 1 megabyte of data to a file,
lseek to the beginning and start writing again - and you go over quota
on the *second* write even though you're over-writing already existing
data. Can happen if you're compressing, and the second write doesn't
compress as well as the first. (To be fair, we already have similar
issues with sparse files - but at least 'tar --sparse' has an easy way
to deal with it compared to this. ;)
Sorry, may be I'm out of the context, but here is my view.

In case of compression in the kernel space you may take into account the size of file in the _uncompressed_ form and how much it takes in the compressed form - doesn't matter. So, no problems with rewriting.

Moreover, are you sure that the current quota model is enough for FSes with on-fligh compression? The model should probably be extended/changed.

Problems with quota and accounting is not the reason to forbid the on-flight compression. And they don't have to co-exist well.

--
Best Regards,
Artem B. Bityuckiy,
St.-Petersburg, Russia.
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