block-highmem-all-19

Hi,

In preparation of 2.4.20-pre, here's an updated version of the block-highme patch. This enables block drivers to do I/O to high memory pages instead of reverting to low memory bounce buffers.

Changes:

- (scsi) Fix critical SCpnt->request_buffer -> SCpnt->request.buffer error

- (scsi) Backport __init_io() changes from 2.5, that enable us to politely back off on queueing more I/O with any failure. We use this now instead of reverting to single segment requests on sgtable allocation failures. For a highmem host this got nasty, because we had to map the buffer_head and use a bounce buffer for that single segment anyway. That is now eliminated. Even for non-highmem I/O the single segment fall back is slower because of the over head associated with command setup etc.

*.kernel.org/pub/linux/kernel/people/axboe/patches/v2.4/2.4.19-pre10/block-highmem-all-19.bz2

Enjoy,

Jens Axboe