On Sun, Mar 09, 2025 at 12:23:05AM +0800, Ming Lei wrote:
> lo_rw_aio() is only called for READ/WRITE operation, which can be
> figured out from request directly, so remove 'rw' parameter from
> lo_rw_aio(), meantime rename the local variable as 'dir' which matches
> the actual use more.
>
> Meantime merge lo_read_simple() and lo_write_simple() into
> lo_rw_simple().
That's two entirely separate things, please split them into separate
patches.
static int lo_rw_simple(struct loop_device *lo, struct request *rq, loff_t pos)
> {
> struct bio_vec bvec;
> struct req_iterator iter;
> struct iov_iter i;
> ssize_t len;
>
> + if (req_op(rq) == REQ_OP_WRITE) {
> + int ret;
> +
> + rq_for_each_segment(bvec, rq, iter) {
> + ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
> + if (ret < 0)
> + break;
> + cond_resched();
> + }
> + return ret;
> + }
> +
> rq_for_each_segment(bvec, rq, iter) {
.. and nothing is really merged here. So unless you actually merge
some code later this part doesn't seem particularly useful.
> struct request *rq = blk_mq_rq_from_pdu(cmd);
> + int dir = (req_op(rq) == REQ_OP_READ) ? ITER_DEST : ITER_SOURCE;
> struct bio *bio = rq->bio;
> struct file *file = lo->lo_backing_file;
> struct bio_vec tmp;
> @@ -448,7 +442,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> }
> atomic_set(&cmd->ref, 2);
>
> - iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
> + iov_iter_bvec(&iter, dir, bvec, nr_bvec, blk_rq_bytes(rq));
> iter.iov_offset = offset;
>
> cmd->iocb.ki_pos = pos;
> @@ -457,7 +451,7 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
> cmd->iocb.ki_flags = IOCB_DIRECT;
> cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
>
> - if (rw == ITER_SOURCE)
> + if (dir == ITER_SOURCE)
i'd just use the request direction check here, and then open code
the iter source/dest in the iov_iter_bvec call.
> case REQ_OP_READ:
> if (cmd->use_aio)
> - return lo_rw_aio(lo, cmd, pos, ITER_DEST);
> + return lo_rw_aio(lo, cmd, pos);
> else
> - return lo_read_simple(lo, rq, pos);
> + return lo_rw_simple(lo, rq, pos);
Not entirely new here, but there is no reason to use an else after a
return.
