[coreutils] Patch to introduce FIEMAP to cp for effieicent sparse file copy

[jeff.liu]

Hello,

I'd like to introduce fiemap(available in mainline kernel-2.6.27 at least) to 
cp/mv commands
for efficient sparse file copy.

For the filesytems with FIEMAP supported, call ioctl(..FS_IOC_FIEMAP) could 
return the extents info
mapped to a file except holes.
This would result in much faster backups for any kind of sparse files.

For now, it works for some simple tests against cp(1), any help tests are 
appreciated!

I like to send out the patches for your guys review, the test scripts will be 
added to
coreutils/tests and send out soon.

I'll add the fiemap support for mv(1) once the above functions become stable.

Any comments are welcomed!



Best Regards,
-Jeff