On Sun, 2008-02-24 at 07:57 +0100, Jörn Engel wrote: > Could a naïve implementation of this get exploited by doing a large > number of truncates that just shave single bytes off various files?
Yeah, which is why _my_ naïve implementation would do it for truncate-to-zero instead of just _any_ truncate (which could even be truncate-to-larger). A more complex version might allow _any_ transaction to eat into the ALLOC_DELETION pool if it is ultimately going to reduce the amount of space taken on the file system -- even overwriting 'real' data with zeroes which compress better. That's going to be hard to calculate in the general case though. If allowing only truncate-to-zero isn't good enough, perhaps we could allow truncation to use the ALLOC_DELETION pool when it's going to obsolete at least one full data node. That's not so hard to check. -- dwmw2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
