lk 2.5.31 sg version 3.5.27 re-adds dio

This version of sg for the lk 2.5 series re-adds direct IO support using work done by Kai Makisara (on st driver, posted 2002/7/29).

Changelog:
Changes since 3.5.26 (20020708)
- re-add direct IO using Kai Makisara's work
- re-tab to 8, start using C99-isms
- simplify memory management

Like Kai's patch, this one needs kernel/ksyms.c altered to export get_user_pages(). Kai's worker routines st_map_user_pages() and st_unmap_user_pages() are duplicated as is. Hopefully these routines will find a home in a library soon.

The re-tabbing makes the patches rather large so here are 2 urls:
This tarball contains sg.h and sg.c

	http://www.torque.net/sg/p/sg3527.tgz
This gzipped patch is against lk 2.5.31 and touches
kernel/ksyms.c as well
	http://www.torque.net/sg/p/sg_3527_lk2531.diff.gz

Testing is ongoing, everything works apart from "zero copy" copy. That uses mmap-ed IO on the read side and direct IO on the write side. Not too many people would be using that I suspect.

Doug Gilbert