Dear linux-mm team,

This patch is for patching the mm and fs stuff to make the Linux 2.4.21 
swap code to allow a concept of modularized swap methods. This concept 
and swap code is originally from Justus Heine who created the NFS swap 
patch for 2.2 and 2.4 . I've extracted the code and modified to make it 
as a generic swap module code. The vanilla kernel swap code is been 
moved to a file fs/blkdev_swap.c which is for normal plain block device 
swaps. Users can configure the kernel to include the local block device 
swap code or compile it as a module. Developers can also develop their 
own swap methods instead of using the plain swap code (may be some 
crypto for security reasons) . I've been using this API to develop NFS 
swap and netswap code for a year an more. This patch has been tested for 
more than a year in a production environment on smp and non-smp (I think 
it is quite stable though). Please find it useful.

regards,
David Chow