How to generate a large file allocating space

Alex Bligh alex at
Sun Oct 31 18:09:26 UTC 2010

--On 31 October 2010 19:46:09 +0100 Matija Nalis <mnalis-ml at> 

> Sorry, I don't. debugfs(8) only appears to have read-only support for
> reading extents, and not for (re-)writing them, so I guess you'll have to
> find some function in libext2fs if it exists (or write your own if it
> doesn't) to use on unmounted fs.

Yes. I need to iterate through the extents. debugfs does that but I don't
know how to change the flag or (more relevantly) whether it is safe to do

Alex Bligh

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