RDMA/umem: Combine contiguous PAGE_SIZE regions in SGEs

Combine contiguous regions of PAGE_SIZE pages into single scatter list
entry while building the scatter table for a umem. This minimizes the
number of the entries in the scatter list and reduces the DMA mapping
overhead, particularly with the IOMMU.

Set default max_seg_size in core for IB devices to 2G and do not combine
if we exceed this limit.

Also, purge npages in struct ib_umem as we now DMA map the umem SGL with
sg_nents and npage computation is not needed. Drivers should now be using
ib_umem_num_pages(), so fix the last stragglers.

Move npages tracking to ib_umem_odp as ODP drivers still need it.

Suggested-by: Jason Gunthorpe <jgg@ziepe.ca>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Adit Ranadive <aditr@vmware.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Tested-by: Gal Pressman <galpress@amazon.com>
Tested-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 6f8c36fcda78..97219143f16f 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -526,7 +526,7 @@ static int ib_umem_odp_map_dma_single_page(
 		}
 		umem_odp->dma_list[page_index] = dma_addr | access_mask;
 		umem_odp->page_list[page_index] = page;
-		umem->npages++;
+		umem_odp->npages++;
 	} else if (umem_odp->page_list[page_index] == page) {
 		umem_odp->dma_list[page_index] |= access_mask;
 	} else {
@@ -752,7 +752,7 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
 			}
 			umem_odp->page_list[idx] = NULL;
 			umem_odp->dma_list[idx] = 0;
-			umem->npages--;
+			umem_odp->npages--;
 		}
 	}
 	mutex_unlock(&umem_odp->umem_mutex);