On Sun 2008-02-24 18:57:32, David Woodhouse wrote: > > On Sun, 2008-02-24 at 07:57 +0100, Jörn Engel wrote: > > Could a na??ve 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_ na??ve 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.
I believe truncate-to-zero is good enough. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/
