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

On 8/30/18 12:53 PM, Logan Gunthorpe wrote:

QUEUE_FLAG_PCI_P2P is introduced meaning a driver's request queue
supports targeting P2P memory.

When a request is submitted we check if PCI P2PDMA memory is assigned
to the first page in the bio. If it is, we ensure the queue it's
submitted to supports it, and enforce REQ_NOMERGE.

I think this belongs in the caller - both the validity check, and
passing in NOMERGE for this type of request. I don't want to impose
this overhead on everything, for a pretty niche case.

-- 
Jens Axboe