On 1/27/15, Christoph Hellwig <hch@xxxxxx> wrote: > On Mon, Jan 26, 2015 at 10:02:30AM +0800, Ming Lei wrote: >> >> Sorry, I have one question: I understand one bvec should only cover >> >> one page, but >> >> one sg may cover lots of pages, so could ITER_BVEC handle that >> >> correctly? >> > >> > Each scatterlist entry only contains a single page, which is returned >> >> I mean scatterlist does not guarantee that, and one sg entry often >> contains lots of pages, which DMA/bus address is continuous. > > But we still get away with using page_address(), so from the VM > point of view that matters here it's the same as a single high order > page. Yes, but simply passing the page, offset and length from sg to bvec is misleading, so it may be better to add comment about the fact of single page sg entry. Thanks Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
