On Wed, Mar 24 2021 at 8:19am -0400,
Ming Lei <ming.lei@xxxxxxxxxx> wrote:
> From: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
>
> IO polling is enabled when all underlying target devices are capable
> of IO polling. The sanity check supports the stacked device model, in
> which one dm device may be build upon another dm device. In this case,
> the mapped device will check if the underlying dm target device
> supports IO polling.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> drivers/md/dm-table.c | 24 ++++++++++++++++++++++++
> drivers/md/dm.c | 14 ++++++++++++++
> include/linux/device-mapper.h | 1 +
> 3 files changed, 39 insertions(+)
>
...
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 50b693d776d6..fe6893b078dc 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1720,6 +1720,19 @@ static blk_qc_t dm_submit_bio(struct bio *bio)
> return ret;
> }
>
> +static bool dm_bio_poll_capable(struct gendisk *disk)
> +{
> + int ret, srcu_idx;
> + struct mapped_device *md = disk->private_data;
> + struct dm_table *t;
> +
> + t = dm_get_live_table(md, &srcu_idx);
> + ret = dm_table_supports_poll(t);
> + dm_put_live_table(md, srcu_idx);
> +
> + return ret;
> +}
> +
I know this code will only get called by blk-core if bio-based but there
isn't anything about this method's implementation that is inherently
bio-based only.
So please rename from dm_bio_poll_capable to dm_poll_capable
Other than that:
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> /*-----------------------------------------------------------------
> * An IDR is used to keep track of allocated minor numbers.
> *---------------------------------------------------------------*/
> @@ -3132,6 +3145,7 @@ static const struct pr_ops dm_pr_ops = {
> };
>
> static const struct block_device_operations dm_blk_dops = {
> + .poll_capable = dm_bio_poll_capable,
> .submit_bio = dm_submit_bio,
> .open = dm_blk_open,
> .release = dm_blk_close,
