| Message ID | 1477728600-12938-16-git-send-email-tom.leiming@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Btw, the lib/iov_iter.c code that iterates over bvec currently expects single-page segments. Is the loop code fine with that? Even if it is I think we'd be much better off if it becomes multipage segment aware. -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Oct 31, 2016 at 11:31 PM, Christoph Hellwig <hch@infradead.org> wrote: > Btw, the lib/iov_iter.c code that iterates over bvec currently > expects single-page segments. Is the loop code fine with that? lib/iov_iter.c has switched to bvec iterator already in the mp-bvec preparing patchset, so every thing will be fine after multipage bvec is enabled. Another multipage bvec benefit for lib/iov_iter.c(dio) is that we can return whole pages in one segment, instead of one page each time, such as iov_iter_get_pages(), but that can be a follow-up optimization. > Even if it is I think we'd be much better off if it becomes multipage > segment aware. This patch is for auditing possible effect with multipage bvec, so looks we should expose as much as possible direct access to bvec table. Thanks, Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index fa1b7a90ba11..55ce4226590d 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -485,6 +485,11 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, /* nomerge for loop request queue */ WARN_ON(cmd->rq->bio != cmd->rq->biotail); + /* + * For multipage bvec support, it is safe to pass the bvec + * table to iov iterator, because iov iter still uses bvec + * iter helpers to travese bvec. + */ bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, bio_segments(bio), blk_rq_bytes(cmd->rq));
Signed-off-by: Ming Lei <tom.leiming@gmail.com> --- drivers/block/loop.c | 5 +++++ 1 file changed, 5 insertions(+)