ia64/sba_iommu: return error code from sba_map_sg_attrs()

The .map_sg() op now expects an error code instead of zero on failure.

In the case of a dma_mapping_error() return -EIO as the actual cause
is opaque here.

sba_coalesce_chunks() may only presently fail if sba_alloc_range()
fails, which in turn only fails if the iommu is out of mapping
resources, hence a -ENOMEM is used in that case.
Signed-off-by: Martin Oliveira <martin.oliveira@eideticom.com>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

arch/ia64/hp/common/sba_iommu.c

@@ -1459,7 +1459,7 @@ static int sba_map_sg_attrs(struct device *dev, struct scatterlist *sglist,
 		sglist->dma_address = sba_map_page(dev, sg_page(sglist),
 				sglist->offset, sglist->length, dir, attrs);
 		if (dma_mapping_error(dev, sglist->dma_address))
-			return 0;
+			return -EIO;
 		return 1;
 	}
 
@@ -1486,7 +1486,7 @@ static int sba_map_sg_attrs(struct device *dev, struct scatterlist *sglist,
 	coalesced = sba_coalesce_chunks(ioc, dev, sglist, nents);
 	if (coalesced < 0) {
 		sba_unmap_sg_attrs(dev, sglist, nents, dir, attrs);
-		return 0;
+		return -ENOMEM;
 	}
 
 	/*