[PATCH] shred: overwrite inode storage used by some file systems

[Pádraig Brady]

Paul reminded me that for small files, their storage might
be completely within an inode.  Now that would not be cleared
if one was writing a full block, which shred does by default.
Now that full block write to clear the slack space at the end
of a file is useful, especially is used in a consistent manner
to remove all files from a file system, so to cater for both
use cases you could write the small amount first, and then
pad out to the full block.

Now we shouldn't jump through any hoops to improve shredding
of regular files, since there are so many edge cases we can't
handle with journalling file systems etc., but in this case
the improvement is easy and so probably worth adding.

Proposed untested implementation attached.
Also noted therein is the possiblity for also handling:
http://en.wikipedia.org/wiki/Tail_packing

thanks,
Pádraig.

shred-inode-data.patch
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