[PATCH] block: disable block layer bouncing for most memory on 64bit systems

[PATCH] block: disable block layer bouncing for most memory on 64bit systems

The low level PCI DMA mapping functions should handle it in most cases.

This should fix problems with depleting the DMA zone early. The old
code used precious GFP_DMA memory in many cases where it was not needed.

Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>