On Wed, 2007-06-27 at 23:36 +1000, David Chinner wrote:

.... Allows setup_swap_extents() to use preallocated files on XFS
filesystems for swap files without ever needing to convert them.

Using unwritten extents (as opposed to the MKSWAP flag mentioned
earlier) has the unfortunate down side of requiring transactions,
possibly additional IO, and memory allocation during swap.  (but,
this patch should probably go in regardless, as teaching generic
code about unwritten extents is not a bad idea).

cheers.

--
Nathan