On Thu, Oct 18, 2018 at 09:18:14PM +0800, Ming Lei wrote:

Turns out q->dma_alignement should be stack limit because now bvec table
is immutalbe, the underlying queue's dma alignment has to be perceptible
by stack driver, so IO buffer can be allocated as dma aligned before
adding to bio.

So this patch moves .dma_alignment into q->limits and prepares for
making it as one stacked limit.

Looks fine:

Reviewed-by: Christoph Hellwig <hch@lst.de>