blk_queue_dma_alignment (9) - Linux Manuals
blk_queue_dma_alignment: set dma length and memory alignment
blk_queue_dma_alignment - set dma length and memory alignment
void blk_queue_dma_alignment(struct request_queue
* q, int mask);
- the request queue for the device
- alignment mask
set required memory and length alignment for direct dma transactions. this is used when building direct io requests for the queue.