iommu sg merging: call blk_queue_segment_boundary in __scsi_alloc_queue

request_queue and device struct must have the same value of a segment
size limit. This patch adds blk_queue_segment_boundary in
__scsi_alloc_queue so LLDs don't need to call both
blk_queue_segment_boundary and set_dma_max_seg_size. A LLD can change
the default value (64KB) can call device_dma_parameters accessors like
pci_set_dma_max_seg_size when allocating scsi_host.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Jeff Garzik <jeff@garzik.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/scsi/scsi_lib.c

@@ -1569,6 +1569,7 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
 					 request_fn_proc *request_fn)
 {
 	struct request_queue *q;
+	struct device *dev = shost->shost_gendev.parent;
 
 	q = blk_init_queue(request_fn, NULL);
 	if (!q)
@@ -1584,6 +1585,8 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
 	blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
 	blk_queue_segment_boundary(q, shost->dma_boundary);
 
+	blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
+
 	if (!shost->use_clustering)
 		clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);