On Sun, Mar 04, 2007 at 08:11:17PM +0000, Anton Altaparmakov wrote:

glibc cannot ever be smart enough because a file system driver will  
always know better and be able to do things in a much more optimized  
way.

Please read the thread again.  That is not what anyone proposed.
The issues we're discussing is whether fallback for a filesystem that
does not support preallocation natively should be done in kernelspace
or in userspace.