Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests

[Christoph Hellwig]

On Wed, Sep 05, 2018 at 01:54:31PM -0600, Jens Axboe wrote:
> On 9/5/18 1:56 PM, Christoph Hellwig wrote:
> > On Wed, Sep 05, 2018 at 01:45:04PM -0600, Jens Axboe wrote:
> >> The point is that the caller doesn't necessarily know where the bio
> >> will end up, hence the caller can't fully check if the whole stack
> >> supports P2P.
> > 
> > The caller must necessarily know where the bio will end up, as for P2P
> > support we need to query if the bio target is P2P capable vs the
> > source of the P2P memory.
> 
> Then what's the point of having the check at all?

Just an additional little safe guard.  If you think it isn't worth
it I guess we can just drop it for now.