Re: [PATCH v3] virtio_blk: add VIRTIO_BLK_F_LIFETIME feature support

[Chaitanya Kulkarni <chaitanyak@nvidia.com>]

On 12/5/22 10:24, Jens Axboe wrote:
> On 12/5/22 9:20 AM, Alvaro Karsz wrote:
>> Implement the VIRTIO_BLK_F_LIFETIME feature for VirtIO block devices.
>>
>> This commit introduces a new ioctl command, VBLK_LIFETIME.
>>
>> VBLK_LIFETIME ioctl asks for the block device to provide lifetime
>> information by sending a VIRTIO_BLK_T_GET_LIFETIME command to the device.
>>
>> lifetime information fields:
>>
>> - pre_eol_info: specifies the percentage of reserved blocks that are
>> 		consumed.
>> 		optional values following virtio spec:
>> 		*) 0 - undefined.
>> 		*) 1 - normal, < 80% of reserved blocks are consumed.
>> 		*) 2 - warning, 80% of reserved blocks are consumed.
>> 		*) 3 - urgent, 90% of reserved blocks are consumed.
>>
>> - device_lifetime_est_typ_a: this field refers to wear of SLC cells and
>> 			     is provided in increments of 10used, and so
>> 			     on, thru to 11 meaning estimated lifetime
>> 			     exceeded. All values above 11 are reserved.
>>
>> - device_lifetime_est_typ_b: this field refers to wear of MLC cells and is
>> 			     provided with the same semantics as
>> 			     device_lifetime_est_typ_a.
>>
>> The data received from the device will be sent as is to the user.
>> No data check/decode is done by virtblk.
> 
> Is this based on some spec? Because it looks pretty odd to me. There
> can be a pretty wide range of two/three/etc level cells with wildly
> different ranges of durability. And there's really not a lot of slc
> for generic devices these days, if any.
> 

This is exactly what I said on initial version about new types ...

-ck