[PATCH] nvme-rdma: Fix T10-PI when SW doesn't generate/verify metadata

[Max Gurtovoy]

On 07/06/2023 8:08, Christoph Hellwig wrote:
> On Tue, Jun 06, 2023 at 01:51:30PM +0300, Israel Rukshin wrote:
>> When the SW doesn't generate/verify metadata, the SG length is
>> smaller than the transfer length.
> 
> What is "the SW"?

better to say the block layer.

> 
>> length when there is no metadata SGL. The bug reproduces when
>> setting read_verify/write_generate to 0 at the child multipath
>> device or at the primary device when multipath is disabled. Note
>> that setting those to 0 on the multipath device doesn't have any
>> impact on the I/Os.
> 
> And we really need to prevent this from happening per the last
> discussion.  Please submit a patch to fail adding a new path to
> a ns_head if the PI settings mismatch.

We're working on it.

I'm not sure what is the intention regarding the support for having 
shared namespaces that are not under multipath. There is some comment in 
the code that some support will be removed.
Will we allow the same namespace to be exposed twice ? or only the first 
one will be exposed in case there is no match in the PI-offload 
capabilities ?

but the above doesn't answer what is the behavior we should have if we 
change the read_verify/write_generate of the head device ? should it 
propagate to the children ?