Re: [PATCH v2] block: ublk: enable zoned storage support

[Damien Le Moal]

On 3/2/23 16:31, Andreas Hindborg wrote:
>>> +struct ublk_param_zoned {
>>> +	__u64	max_open_zones;
>>> +	__u64	max_active_zones;
>>> +	__u64	max_append_size;
>>> +};
>>
>> Is the above zoned parameter enough for future extension?
>> Does ZNS need extra parameter? Or some zoned new(important) features?
> 
> @Damien, @Hans, @Matias, what do you think?

Yes, add some reserved fields. The struct is 24 B for now, you can make it 32 B.
But it is a little odd: why 64 bits for max open/active zones and max append ?
bio len is 32 bits and number of zones also 32 bits. You do not need 64 bits for
all these fields. Also, no zone model reported with this ? What about write
granularity (for SMR HDDs) too ?

So something like:

struct ublk_param_zoned {
	__u32	model;
	__u32	write_granularity;
	__u32	max_open_zones;
	__u32	max_active_zones;
	__u32	max_append_size;
	__u8	reserved[12];
};

looks better to me. Note sure about the need for model and write_granularity
here though. I did not follow zoned ublk patches.


-- 
Damien Le Moal
Western Digital Research