ib_dma_map_sgtable_attrs() should be mapping the sgls and setting nents
but the ib_uses_virt_dma() path falls back to ib_dma_virt_map_sg()
which will not set the nents in the sgtable.
Check the return value (per the map_sg calling convention) and set
sgt->nents appropriately on success.
Link: https://lore.kernel.org/all/996fa723-18ef-d35b-c565-c9cb9dc2d5e1@xxxxxxx/T/#u
Reported-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Tested-by: Bart Van Assche <bvanassche@xxxxxxx>