Commit e87d66ab authored by Caleb Sander Mateos's avatar Caleb Sander Mateos Committed by Jens Axboe
Browse files

ublk: use rq_for_each_segment() for user copy 



ublk_advance_io_iter() and ublk_copy_io_pages() currently open-code the
iteration over the request's bvecs. Switch to the rq_for_each_segment()
macro provided by blk-mq to avoid reaching into the bio internals and
simplify the code.

Suggested-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarCaleb Sander Mateos <csander@purestorage.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 2299ceec

drivers/block/ublk_drv.c

+19 −51
Original line number Diff line number Diff line
@@ -913,22 +913,29 @@ static const struct block_device_operations ub_fops = { 
	.report_zones =	ublk_report_zones,

};



struct ublk_io_iter {

	struct bio *bio;

	struct bvec_iter iter;

};



/* return how many bytes are copied */

static size_t ublk_copy_io_pages(struct ublk_io_iter *data,

		struct iov_iter *uiter, int dir)

/*

 * Copy data between request pages and io_iter, and 'offset'

 * is the start point of linear offset of request.

 */

static size_t ublk_copy_user_pages(const struct request *req,

		unsigned offset, struct iov_iter *uiter, int dir)

{

	struct req_iterator iter;

	struct bio_vec bv;

	size_t done = 0;



	for (;;) {

		struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);

		void *bv_buf = bvec_kmap_local(&bv);

	rq_for_each_segment(bv, req, iter) {

		void *bv_buf;

		size_t copied;



		if (offset >= bv.bv_len) {

			offset -= bv.bv_len;

			continue;

		}



		bv.bv_offset += offset;

		bv.bv_len -= offset;

		bv_buf = bvec_kmap_local(&bv);

		if (dir == ITER_DEST)

			copied = copy_to_iter(bv_buf, bv.bv_len, uiter);

		else
@@ -940,50 +947,11 @@ static size_t ublk_copy_io_pages(struct ublk_io_iter *data, 
		if (copied < bv.bv_len)

			break;



		/* advance bio */

		bio_advance_iter_single(data->bio, &data->iter, copied);

		if (!data->iter.bi_size) {

			data->bio = data->bio->bi_next;

			if (data->bio == NULL)

				break;

			data->iter = data->bio->bi_iter;

		}

		offset = 0;

	}

	return done;

}



static bool ublk_advance_io_iter(const struct request *req,

		struct ublk_io_iter *iter, unsigned int offset)

{

	struct bio *bio = req->bio;



	for_each_bio(bio) {

		if (bio->bi_iter.bi_size > offset) {

			iter->bio = bio;

			iter->iter = bio->bi_iter;

			bio_advance_iter(iter->bio, &iter->iter, offset);

			return true;

		}

		offset -= bio->bi_iter.bi_size;

	}

	return false;

}



/*

 * Copy data between request pages and io_iter, and 'offset'

 * is the start point of linear offset of request.

 */

static size_t ublk_copy_user_pages(const struct request *req,

		unsigned offset, struct iov_iter *uiter, int dir)

{

	struct ublk_io_iter iter;



	if (!ublk_advance_io_iter(req, &iter, offset))

		return 0;



	return ublk_copy_io_pages(&iter, uiter, dir);

}



static inline bool ublk_need_map_req(const struct request *req)

{

	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;