On Sun, Mar 09, 2025 at 12:23:06AM +0800, Ming Lei wrote:
> + if (rq->bio != rq->biotail) {
This would probably be more self-explaining by checking for cmd->bdev
here.
> + bvec = cmd->bvec;
> + offset = 0;
> + } else {
> + struct bio *bio = rq->bio;
> +
> + offset = bio->bi_iter.bi_bvec_done;
> + bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
> + }
> + iov_iter_bvec(&iter, dir, bvec, nr_bvec, blk_rq_bytes(rq));
> + iter.iov_offset = offset;
And given that bvec and offset are only used here I'd just move the
iov_iter_bvec into the branches and do away with the two variables,
and kill the bio variable as well while at it.
> +static inline unsigned lo_cmd_nr_bvec(struct loop_cmd *cmd)
> +{
> + struct req_iterator rq_iter;
> + struct request *rq = blk_mq_rq_from_pdu(cmd);
> + struct bio_vec tmp;
> + int nr_bvec = 0;
> +
> rq_for_each_bvec(tmp, rq, rq_iter)
> nr_bvec++;
>
> + return nr_bvec;
> +}
> +
> +static int lo_rw_aio_prep(struct loop_device *lo, struct loop_cmd *cmd,
> + unsigned nr_bvec)
The function order is a bit weird. I would expect them to appear in
the rough order that they are called, e.g. lo_cmd_nr_bvec first, then
lo_rw_aio_prep, then the submit helper.
> - /*
> - * Same here, this bio may be started from the middle of the
> - * 'bvec' because of bio splitting, so offset from the bvec
> - * must be passed to iov iterator
> - */
It would be good if this comment didn't get lost.
