[PATCH v2 2/2] nvme-multipath: fix path failover for integrity ns

[Martin K. Petersen]

Hi Max!

> In case the integrity capabilities of the failed path and the failover
> path don't match, we may run into NULL dereference. Free the integrity
> context during the path failover and let the block layer prepare it
> again if needed during bio_submit.

This assumes that the protection information is just an ephemeral
checksum. However, that is not always the case. The application may
store values in the application or storage tags which must be returned
on a subsequent read.

In addition, in some overseas markets (financial, government), PI is a
regulatory requirement. It would be really bad for us to expose a device
claiming PI support and then it turns out the protection isn't actually
always active.

DM multipathing doesn't allow mismatched integrity profiles. I don't
think NVMe should either.

-- 
Martin K. Petersen	Oracle Linux Engineering