Re: [PATCH 6/6] nvme: Add consistency check for zone count

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

On 2020/06/26 6:49, Keith Busch wrote:
> On Thu, Jun 25, 2020 at 02:21:52PM +0200, Javier González wrote:
>>  drivers/nvme/host/zns.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c
>> index 7d8381fe7665..de806788a184 100644
>> --- a/drivers/nvme/host/zns.c
>> +++ b/drivers/nvme/host/zns.c
>> @@ -234,6 +234,13 @@ static int nvme_ns_report_zones(struct nvme_ns *ns, sector_t sector,
>>  		sector += ns->zsze * nz;
>>  	}
>>  
>> +	if (nr_zones < 0 && zone_idx != ns->nr_zones) {
>> +		dev_err(ns->ctrl->device, "inconsistent zone count %u/%u\n",
>> +				zone_idx, ns->nr_zones);
>> +		ret = -EINVAL;
>> +		goto out_free;
>> +	}
>> +
>>  	ret = zone_idx;
> 
> nr_zones is unsigned, so it's never < 0.
> 
> The API we're providing doesn't require zone_idx equal the namespace's
> nr_zones at the end, though. A subset of the total number of zones can
> be requested here.
> 

Yes, absolutely. zone_idx is not an absolute zone number. It is the index of the
reported zone descriptor in the current report range requested by the user,
which is not necessarily for the entire drive (i.e., provided nr zones is less
than the total number of zones of the disk and/or start sector is > 0). So
zone_idx indicates the actual number of zones reported, it is not the total
number of zones of the drive.

-- 
Damien Le Moal
Western Digital Research