Files full of zeros with coreutils-8.11 and xfs (FIEMAP related?)

[Theodore Tso]

On Apr 16, 2011, at 1:11 AM, Andreas Dilger wrote:

> In that case, it means cp should just always use FIEMAP_FLAG_SYNC, which is fine. 

Except that if someone is copying a large delay allocated file, it will cause 
the file to immediately snapped to disk, which might not be the greatest
thing in the world.  Christoph is write, SEEK_HOLE and SEEK_DATA are
a much better API for what cp woulld lke to do.  Unfortunately it hasn't
been implemented yet in the VFS...

- Ted