Re: [PATCH 05/16] nvme: zns: Allow ZNS drives that have non-power_of_2 zone size

Hannes Reinecke
2022-05-04T17:32:48Z

On 4/27/22 09:02, Pankaj Raghav wrote:
> Remove the condition which disallows non-power_of_2 zone size ZNS drive
> to be updated and use generic method to calculate number of zones
> instead of relying on log and shift based calculation on zone size.
>
> The power_of_2 calculation has been replaced directly with generic
> calculation without special handling. Both modified functions are not
> used in hot paths, they are only used during initialization &
> revalidation of the ZNS device.
>
> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
> drivers/nvme/host/zns.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index 9f81beb4df4e..2087de0768ee 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -101,13 +101,6 @@ int nvme_update_zone_info(struct nvme_ns *ns, unsigned lbaf)
> }
>
> ns->zsze = nvme_lba_to_sect(ns, le64_to_cpu(id->lbafe[lbaf].zsze));
> - if (!is_power_of_2(ns->zsze)) {
> - dev_warn(ns->ctrl->device,
> - "invalid zone size:%llu for namespace:%u\n",
> - ns->zsze, ns->head->ns_id);
> - status = -ENODEV;
> - goto free_data;
> - }
>
> blk_queue_set_zoned(ns->disk, BLK_ZONED_HM);
> blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
> @@ -129,7 +122,7 @@ static void *nvme_zns_alloc_report_buffer(struct nvme_ns *ns,
> sizeof(struct nvme_zone_descriptor);
>
> nr_zones = min_t(unsigned int, nr_zones,
> - get_capacity(ns->disk) >> ilog2(ns->zsze));
> + div64_u64(get_capacity(ns->disk), ns->zsze));
>
Same here; please add a helper calculating the number of zones for a
given disk.

> bufsize = sizeof(struct nvme_zone_report) +
> nr_zones * sizeof(struct nvme_zone_descriptor);
> @@ -197,7 +190,7 @@ int nvme_ns_report_zones(struct nvme_ns *ns, sector_t sector,
> c.zmr.zrasf = NVME_ZRASF_ZONE_REPORT_ALL;
> c.zmr.pr = NVME_REPORT_ZONE_PARTIAL;
>
> - sector &= ~(ns->zsze - 1);
> + sector = rounddown(sector, ns->zsze);
> while (zone_idx < nr_zones && sector < get_capacity(ns->disk)) {
> memset(report, 0, buflen);
>
Please be a bit more consistent. In the previous patches you always had
a condition to check if it's a power_of_2 zone size, but here you are
using the same calculation for each disk.
So please use the check in all locations, or add a comment why the
generic calculation is okay to use here.

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
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