Metadata integrity, single segment and peer-to-peer

[Leon Romanovsky]

On Mon, Oct 20, 2025, at 20:04, Keith Busch wrote:
> On Mon, Oct 20, 2025 at 02:50:04PM +0300, Leon Romanovsky wrote:
>> Hi Keith,
>> 
>> I'm looking on the nvme_pci_setup_meta_mptr() implementation [1] and
>> don't see is_pci_p2pdma_page() which exists in
>> nvme_pci_setup_data_simple() [2]. Is it intentionally? Can single
>> segment be p2p transfer?
>
> We may be calling unnecessarily dma_unmap_page in that case for mptr,
> but I think that still works anyway.

How? dma_map_bvec() is actually dma_map_page_attrs() and that function doesn't handle PCI_P2PDMA_MAP_BUS_ADDR and PCI_P2PDMA_MAP_THRU_HOST_BRIDGE states.

Thanks