iommu sg merging: IA64: make sba_iommu respect the segment size limits

This patch makes sba iommu respect segment size limits when merging sg
lists.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: NJens Axboe <jens.axboe@oracle.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/ia64/hp/common/sba_iommu.c

@@ -1265,7 +1265,7 @@ sba_fill_pdir(
  * the sglist do both.
  */
 static SBA_INLINE int
-sba_coalesce_chunks( struct ioc *ioc,
+sba_coalesce_chunks(struct ioc *ioc, struct device *dev,
 	struct scatterlist *startsg,
 	int nents)
 {
@@ -1275,6 +1275,7 @@ sba_coalesce_chunks( struct ioc *ioc,
 	struct scatterlist *dma_sg;        /* next DMA stream head */
 	unsigned long dma_offset, dma_len; /* start/len of DMA stream */
 	int n_mappings = 0;
+	unsigned int max_seg_size = dma_get_max_seg_size(dev);
 
 	while (nents > 0) {
 		unsigned long vaddr = (unsigned long) sba_sg_address(startsg);
@@ -1314,6 +1315,9 @@ sba_coalesce_chunks( struct ioc *ioc,
 			    > DMA_CHUNK_SIZE)
 				break;
 
+			if (dma_len + startsg->length > max_seg_size)
+				break;
+
 			/*
 			** Then look for virtually contiguous blocks.
 			**
@@ -1441,7 +1445,7 @@ int sba_map_sg(struct device *dev, struct scatterlist *sglist, int nents, int di
 	** w/o this association, we wouldn't have coherent DMA!
 	** Access to the virtual address is what forces a two pass algorithm.
 	*/
-	coalesced = sba_coalesce_chunks(ioc, sglist, nents);
+	coalesced = sba_coalesce_chunks(ioc, dev, sglist, nents);
 
 	/*
 	** Program the I/O Pdir