[PATCH v3 09/10] nvme: add handling for app_tag

[Kanchan Joshi]

On 8/29/2024 8:30 AM, Martin K. Petersen wrote:
> 
> Anuj,
> 
>> With user integrity buffer, there is a way to specify the app_tag. Set
>> the corresponding protocol specific flags and send the app_tag down.
> 
> This assumes the app tag is the same for every block in the I/O? That's
> not how it's typically used (to the extent that it is used at all due to
> the value 0xffff acting as escape).
> 

NVMe spec allows only one value to be passed in each read/write command 
(LBAT for write, and ELBAT for read). And that's what controller checks 
for the entire block range covered by one command.
So per-io tag rather than per-block tag. The integrity buffer creator is 
supposed to put the same application-tag for each block if it is sending 
multi-block IO.