quoted

This ensures all proper DMA layer handling is taken care of by the
SCSI midlayer.

Maybe not entirely related to this series, but it looks like the SCSI
layer is changing the device global dma_set_max_seg_size() - at least
in RDMA the dma device is being shared between many users, so we
really don't want SCSI to make this value smaller.

Can we do something about this?

srp seems to do the right thing:
target_host->max_segment_size = ib_dma_max_seg_size(ibdev);

But iser does not, which means that scsi limits it to:
BLK_MAX_SEGMENT_SIZE (64k)

I can send a fix to iser.

Wondering about other values too, and the interaction with the new
combining stuff in umem.c

The only other values AFAICT is the dma_boundary that rdma llds don't
set...