Re: remove dma_virt_ops v2

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Nov 06, 2020 at 07:19:31PM +0100, Christoph Hellwig wrote:
> Hi Jason,
> 
> this series switches the RDMA core to opencode the special case of
> devices bypassing the DMA mapping in the RDMA ULPs.  The virt ops
> have caused a bit of trouble due to the P2P code node working with
> them due to the fact that we'd do two dma mapping iterations for a
> single I/O, but also are a bit of layering violation and lead to
> more code than necessary.
> 
> Tested with nvme-rdma over rxe.
> 
> Note that the rds changes are untested, as I could not find any
> simple rds test setup.
> 
> Changes since v2:
>  - simplify the INFINIBAND_VIRT_DMA dependencies
>  - add a ib_uses_virt_dma helper
>  - use ib_uses_virt_dma in nvmet-rdma to disable p2p for virt_dma devices
>  - use ib_dma_max_seg_size in umem
>  - stop using dmapool in rds
> 
> Changes since v1:
>  - disable software RDMA drivers for highmem configs
>  - update the PCI commit logs

Lets give Santosh a little longer for RDS, I've grabbed the precursor
parts to for-next for now:

 nvme-rdma: Use ibdev_to_node instead of dereferencing ->dma_device
 RDMA: Lift ibdev_to_node from rds to common code
 RDMA/core: Remove ib_dma_{alloc,free}_coherent
 RDMA/umem: Use ib_dma_max_seg_size instead of dma_get_max_seg_size
 RMDA/sw: Don't allow drivers using dma_virt_ops on highmem configs

Will get the rest next week regardless.

Thanks,
Jason