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

[Jens Axboe <axboe@kernel.dk>]

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.

-- 
Jens Axboe