[PATCH 03/11] block: remove the BIP_IP_CHECKSUM flag

[Christoph Hellwig]

On Tue, Jun 11, 2024 at 03:51:27PM -0400, Martin K. Petersen wrote:
> > But how do you even toggle the flag?  There is no no code to do that.
> > And if you already have a special kernel module for that it really
> > should just use a passthrough request to take care of that.
> 
> A passthrough command to the controller?

A passthrough command to the LU that has a mismatching checksum.

> > Note that unlike the NOCHECK flag which I just cleaned up because they
> > were unused, this one actually does get in the way of the architecture
> > of the whole series :( We could add a per-bip csum_type but it would
> > feel really weird.
> 
> Why would it feel weird? That's how it currently works.

Because there's no way to have it set to anything but the per-queue
one.  

> The qualification tool issues a flurry of commands injecting errors at
> various places in the stack to identify that the right entity (block
> layer, controller, storage device) catch a bad checksum, reference tag,
> etc.

How does it do that?  There's no actualy way to make it mismatch.