Re: [PATCH 3/4] nvme: Add consistency check for zone count

[Damien Le Moal <Damien.LeMoal@wdc.com>]

On 2020/07/02 15:55, Javier González wrote:
> From: Javier González <javier.gonz@samsung.com>
> 
> Since the number of zones is calculated through the reported device
> capacity and the ZNS specification allows to report the total number of
> zones in the device, add an extra check to guarantee consistency between
> the device and the kernel.
> 
> Also, fix a checkpatch warning: unsigned -> unsigned int in the process
> 
> Signed-off-by: Javier González <javier.gonz@samsung.com>
> Signed-off-by: SelvaKumar S <selvakuma.s1@samsung.com>
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
> ---
>  drivers/nvme/host/core.c |  2 +-
>  drivers/nvme/host/nvme.h |  6 ++++--
>  drivers/nvme/host/zns.c  | 39 ++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 43 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> index 1f5c7fc3d2c9..8b9c69172931 100644
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -1994,7 +1994,7 @@ static int __nvme_revalidate_disk(struct gendisk *disk, struct nvme_id_ns *id)
>  	case NVME_CSI_NVM:
>  		break;
>  	case NVME_CSI_ZNS:
> -		ret = nvme_update_zone_info(disk, ns, lbaf);
> +		ret = nvme_update_zone_info(disk, ns, lbaf, le64_to_cpu(id->nsze));
>  		if (ret)
>  			return ret;
>  		break;
> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> index 662f95fbd909..ef80e0b4df56 100644
> --- a/drivers/nvme/host/nvme.h
> +++ b/drivers/nvme/host/nvme.h
> @@ -407,6 +407,7 @@ struct nvme_ns {
>  	u32 sws;
>  	u8 pi_type;
>  #ifdef CONFIG_BLK_DEV_ZONED
> +	u64 nr_zones;
>  	u64 zsze;
>  #endif
>  	unsigned long features;
> @@ -700,7 +701,7 @@ static inline void nvme_mpath_start_freeze(struct nvme_subsystem *subsys)
>  
>  #ifdef CONFIG_BLK_DEV_ZONED
>  int nvme_update_zone_info(struct gendisk *disk, struct nvme_ns *ns,
> -			  unsigned lbaf);
> +			  unsigned int lbaf, sector_t nsze);
>  
>  int nvme_report_zones(struct gendisk *disk, sector_t sector,
>  		      unsigned int nr_zones, report_zones_cb cb, void *data);
> @@ -720,7 +721,8 @@ static inline blk_status_t nvme_setup_zone_mgmt_send(struct nvme_ns *ns,
>  
>  static inline int nvme_update_zone_info(struct gendisk *disk,
>  					struct nvme_ns *ns,
> -					unsigned lbaf)
> +					unsigned lbaf

missing a comma here. Does this even compiles ?

> +					sector_t nsze)
>  {
>  	dev_warn(ns->ctrl->device,
>  		 "Please enable CONFIG_BLK_DEV_ZONED to support ZNS devices\n");
> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
> index b34d2ed13825..d785d179a343 100644
> --- a/drivers/nvme/host/zns.c
> +++ b/drivers/nvme/host/zns.c
> @@ -32,13 +32,36 @@ static int nvme_set_max_append(struct nvme_ctrl *ctrl)
>  	return 0;
>  }
>  
> +static u64 nvme_zns_nr_zones(struct nvme_ns *ns)
> +{
> +	struct nvme_command c = { };
> +	struct nvme_zone_report report;
> +	int buflen = sizeof(struct nvme_zone_report);
> +	int ret;
> +
> +	c.zmr.opcode = nvme_cmd_zone_mgmt_recv;
> +	c.zmr.nsid = cpu_to_le32(ns->head->ns_id);
> +	c.zmr.slba = cpu_to_le64(0);
> +	c.zmr.numd = cpu_to_le32(nvme_bytes_to_numd(buflen));
> +	c.zmr.zra = NVME_ZRA_ZONE_REPORT;
> +	c.zmr.zrasf = NVME_ZRASF_ZONE_REPORT_ALL;
> +	c.zmr.pr = 0;
> +
> +	ret = nvme_submit_sync_cmd(ns->queue, &c, &report, buflen);
> +	if (ret)
> +		return ret;
> +
> +	return le64_to_cpu(report.nr_zones);
> +}
> +
>  int nvme_update_zone_info(struct gendisk *disk, struct nvme_ns *ns,
> -			  unsigned lbaf)
> +			  unsigned int lbaf, sector_t nsze)
>  {
>  //	struct nvme_effects_log *log = ns->head->effects;
>  	struct request_queue *q = disk->queue;
>  	struct nvme_command c = { };
>  	struct nvme_id_ns_zns *id;
> +	sector_t cap_nr_zones;
>  	int status;
>  
>  	/* Driver requires zone append support */
> @@ -80,6 +103,20 @@ int nvme_update_zone_info(struct gendisk *disk, struct nvme_ns *ns,
>  		goto free_data;
>  	}
>  
> +	ns->nr_zones = nvme_zns_nr_zones(ns);
> +	if (!ns->nr_zones) {
> +		status = -EINVAL;
> +		goto free_data;
> +	}
> +
> +	cap_nr_zones = nvme_lba_to_sect(ns, le64_to_cpu(nsze)) >> ilog2(ns->zsze);
> +	if (ns->nr_zones != cap_nr_zones) {
> +		dev_err(ns->ctrl->device, "inconsistent zone count: %llu/%llu\n",
> +			ns->nr_zones, cap_nr_zones);
> +		status = -EINVAL;
> +		goto free_data;
> +	}
> +

I am not opposed to this, but I am not sure if this adds anything to the checks
in blk_revalidate_disk_zones() as that does a full zone report that is checked
against capacity. This seems more like a test of the drive conformance, checking
that the report header nr_zones is correct...

>  	q->limits.zoned = BLK_ZONED_HM;
>  	q->zone_flags = BLK_ZONE_REP_CAPACITY | BLK_ZONE_REP_OFFLINE;
>  	blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, q);
> 


-- 
Damien Le Moal
Western Digital Research