On Sun, Apr 27, 2025 at 6:05 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
> On Sat, Apr 26, 2025 at 10:58:00PM -0600, Caleb Sander Mateos wrote:
> > In preparation for calling it from outside ublk_dispatch_req(), factor
> > out the code responsible for setting up an incoming ublk I/O request.
> >
> > Signed-off-by: Caleb Sander Mateos <csander@xxxxxxxxxxxxxxx>
> > ---
> > drivers/block/ublk_drv.c | 53 ++++++++++++++++++++++------------------
> > 1 file changed, 29 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > index 01fc92051754..90a38a82f8cc 100644
> > --- a/drivers/block/ublk_drv.c
> > +++ b/drivers/block/ublk_drv.c
> > @@ -1151,17 +1151,44 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq,
> > blk_mq_requeue_request(rq, false);
> > else
> > blk_mq_end_request(rq, BLK_STS_IOERR);
> > }
> >
> > +static void ublk_start_io(struct ublk_queue *ubq, struct request *req,
> > + struct ublk_io *io)
> > +{
> > + unsigned mapped_bytes = ublk_map_io(ubq, req, io);
> > +
> > + /* partially mapped, update io descriptor */
> > + if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
> > + /*
> > + * Nothing mapped, retry until we succeed.
> > + *
> > + * We may never succeed in mapping any bytes here because
> > + * of OOM. TODO: reserve one buffer with single page pinned
> > + * for providing forward progress guarantee.
> > + */
> > + if (unlikely(!mapped_bytes)) {
> > + blk_mq_requeue_request(req, false);
> > + blk_mq_delay_kick_requeue_list(req->q,
> > + UBLK_REQUEUE_DELAY_MS);
> > + return;
> > + }
> > +
> > + ublk_get_iod(ubq, req->tag)->nr_sectors =
> > + mapped_bytes >> 9;
> > + }
> > +
> > + ublk_init_req_ref(ubq, req);
> > +}
> > +
> > static void ublk_dispatch_req(struct ublk_queue *ubq,
> > struct request *req,
> > unsigned int issue_flags)
> > {
> > int tag = req->tag;
> > struct ublk_io *io = &ubq->ios[tag];
> > - unsigned int mapped_bytes;
> >
> > pr_devel("%s: complete: qid %d tag %d io_flags %x addr %llx\n",
> > __func__, ubq->q_id, req->tag, io->flags,
> > ublk_get_iod(ubq, req->tag)->addr);
> >
> > @@ -1204,33 +1231,11 @@ static void ublk_dispatch_req(struct ublk_queue *ubq,
> > pr_devel("%s: update iod->addr: qid %d tag %d io_flags %x addr %llx\n",
> > __func__, ubq->q_id, req->tag, io->flags,
> > ublk_get_iod(ubq, req->tag)->addr);
> > }
> >
> > - mapped_bytes = ublk_map_io(ubq, req, io);
> > -
> > - /* partially mapped, update io descriptor */
> > - if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
> > - /*
> > - * Nothing mapped, retry until we succeed.
> > - *
> > - * We may never succeed in mapping any bytes here because
> > - * of OOM. TODO: reserve one buffer with single page pinned
> > - * for providing forward progress guarantee.
> > - */
> > - if (unlikely(!mapped_bytes)) {
> > - blk_mq_requeue_request(req, false);
> > - blk_mq_delay_kick_requeue_list(req->q,
> > - UBLK_REQUEUE_DELAY_MS);
> > - return;
> > - }
>
> Here it needs to break ublk_dispatch_req() for not completing the
> uring_cmd, however ublk_start_io() can't support it.
Good catch. How about I change ublk_start_io() to return a bool
indicating whether the I/O was successfully started?
Thanks,
Caleb
