Most code of ubd_user.c already uses the os_* functions, so it can be moved to
ubd_kern.c.  This patch simply moves the code without any hidden changes.

The only change is inside io_thread(): since it calls signal(), I created a
little function in ubd_user.c which just calls signal() with the right
parameters.

In a later patch (send together) I'll do some changes, to fix the usage of
errno (which makes this code break when moved in a kernelspace file) and for
some other little cleanups.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>