Re: [PATCH v2 09/11] block: Expose queue nr_zones in sysfs

Ewan D. Milne
2018-10-11T14:42:16Z

So in v2 you moved the #ifdef CONFIG_BLK_DEV_ZONED
so that nr_zones is always present? It was previously
changed to keep the request_queue size smaller.

Would make more sense to make the nr_zones sysfs
code here conditional on CONFIG_BLK_DEV_ZONED?

-Ewan

On Thu, 2018-10-11 at 16:09 +0900, Damien Le Moal wrote:
> Expose through sysfs the nr_zones field of a zoned block device request
> queue. This represents the total number of zones of the device
> calculated using the known disk capacity and zone size.
>
> Exposing this value helps in debugging disk issues as well as
> facilitating scripts based use of the disk (e.g. blktests).
>
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
> block/blk-sysfs.c | 11 +++++++++++
> include/linux/blkdev.h | 2 +-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 3772671cf2bc..f7060a938bf9 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -300,6 +300,11 @@ static ssize_t queue_zoned_show(struct request_queue *q, char *page)
> }
> }
>
> +static ssize_t queue_nr_zones_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(q->nr_zones, page);
> +}
> +
> static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
> {
> return queue_var_show((blk_queue_nomerges(q) << 1) |
> @@ -637,6 +642,11 @@ static struct queue_sysfs_entry queue_zoned_entry = {
> .show = queue_zoned_show,
> };
>
> +static struct queue_sysfs_entry queue_nr_zones_entry = {
> + .attr = {.name = "nr_zones", .mode = 0444 },
> + .show = queue_nr_zones_show,
> +};
> +
> static struct queue_sysfs_entry queue_nomerges_entry = {
> .attr = {.name = "nomerges", .mode = 0644 },
> .show = queue_nomerges_show,
> @@ -727,6 +737,7 @@ static struct attribute *default_attrs[] = {
> &queue_write_zeroes_max_entry.attr,
> &queue_nonrot_entry.attr,
> &queue_zoned_entry.attr,
> + &queue_nr_zones_entry.attr,
> &queue_nomerges_entry.attr,
> &queue_rq_affinity_entry.attr,
> &queue_iostats_entry.attr,
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index c24969b1741b..23ab53d2d4ca 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -593,7 +593,6 @@ struct request_queue {
>
> struct queue_limits limits;
>
> -#ifdef CONFIG_BLK_DEV_ZONED
> /*
> * Zoned block device information for request dispatch control.
> * nr_zones is the total number of zones of the device. This is always
> @@ -612,6 +611,7 @@ struct request_queue {
> * blk_mq_unfreeze_queue().
> */
> unsigned int nr_zones;
> +#ifdef CONFIG_BLK_DEV_ZONED
> unsigned long *seq_zones_bitmap;
> unsigned long *seq_zones_wlock;
> #endif /* CONFIG_BLK_DEV_ZONED */