Hi,

I backported the block layer generic tcq bits and ide tcq parts to
2.4.19-pre.

The IDE bits are nearly identical, they differ only where 2.5 does
things differently than 2.5. In addition, 2.4 has dual code paths
(taskfile i/o is currently disabled per default) so tagging needs to be
started a few places extra.

The block bits have a few extra fixes, some of which have been posted
already.

People who were (rightfully so) afraid to test 2.5 can now play with ide
tagged queueing in 2.4. Works great here.

-- 
Jens Axboe