On 02/04/14 05:28, Mike Snitzer wrote:
> From: Hannes Reinecke <hare@xxxxxxx>
>
> There is no reason why multipath needs to queue requests internally for
> queue_if_no_path or pg_init; we should rather push them back onto the
> request queue.
>
> And while we're at it we can simplify the conditional statement in
> map_io() to make it easier to read.
>
> Since mpath no longer does internal queuing of I/O the table info no
> longer emits the internal queue_size. Instead it displays 1 if queuing
> is being used or 0 if it is not.
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> Cc: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> @@ -391,37 +392,30 @@ static int map_io(struct multipath *m, struct request *clone,
>
> pgpath = m->current_pgpath;
>
> - if (was_queued)
> - m->queue_size--;
> -
> - if (m->pg_init_required) {
> - if (!m->pg_init_in_progress)
> - queue_work(kmultipathd, &m->process_queued_ios);
> - r = DM_MAPIO_REQUEUE;
> - } else if ((pgpath && m->queue_io) ||
> - (!pgpath && m->queue_if_no_path)) {
> - /* Queue for the daemon to resubmit */
> - list_add_tail(&clone->queuelist, &m->queued_ios);
> - m->queue_size++;
> - if (!m->queue_io)
> - queue_work(kmultipathd, &m->process_queued_ios);
> - pgpath = NULL;
> - r = DM_MAPIO_SUBMITTED;
> - } else if (pgpath) {
> - bdev = pgpath->path.dev->bdev;
> - clone->q = bdev_get_queue(bdev);
> - clone->rq_disk = bdev->bd_disk;
> - } else if (__must_push_back(m))
> - r = DM_MAPIO_REQUEUE;
> - else
> - r = -EIO; /* Failed */
> -
> - mpio->pgpath = pgpath;
> - mpio->nr_bytes = nr_bytes;
> -
> - if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io)
> - pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path,
> - nr_bytes);
> + if (pgpath) {
> + if (__pgpath_busy(pgpath))
> + r = DM_MAPIO_REQUEUE;
Sorry I forgot to comment on this.
The above 2 lines should be removed from this patch.
I suggested to add them because the early version of this patch was
going to remove multipath_busy(). It's no longer true.
Removing them will make this patch easier to understand.
Other than that:
Reviewed-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
> + else if (pg_ready(m)) {
> + bdev = pgpath->path.dev->bdev;
> + clone->q = bdev_get_queue(bdev);
> + clone->rq_disk = bdev->bd_disk;
> + mpio->pgpath = pgpath;
> + mpio->nr_bytes = nr_bytes;
> + if (pgpath->pg->ps.type->start_io)
> + pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
> + &pgpath->path,
> + nr_bytes);
> + } else {
> + __pg_init_all_paths(m);
> + r = DM_MAPIO_REQUEUE;
> + }
> + } else {
> + /* No path */
> + if (__must_push_back(m))
> + r = DM_MAPIO_REQUEUE;
> + else
> + r = -EIO; /* Failed */
> + }
>
> spin_unlock_irqrestore(&m->lock, flags);
>
--
Jun'ichi Nomura, NEC Corporation
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