scsi: RDMA/srp: Don't set a max_segment_size when virt_boundary_mask is set

virt_boundary_mask implies an unlimited max_segment_size. Setting both
can lead to data corruption because __blk_rq_map_sg() can split requests
so that the virt_boundary_mask is not respected if max_segment_size is
not UINT_MAX.

Signed-off-by: Christoph Hellwig <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Hannes Reinecke <[e-mail]>
Reviewed-by: John Garry <[e-mail]>
Acked-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/infiniband/ulp/srp/ib_srp.c

···
 	target_host->max_id      = 1;
 	target_host->max_lun     = -1LL;
 	target_host->max_cmd_len = sizeof ((struct srp_cmd *) (void *) 0L)->cdb;
-	target_host->max_segment_size = ib_dma_max_seg_size(ibdev);
 
-	if (!(ibdev->attrs.kernel_cap_flags & IBK_SG_GAPS_REG))
+	if (ibdev->attrs.kernel_cap_flags & IBK_SG_GAPS_REG)
+		target_host->max_segment_size = ib_dma_max_seg_size(ibdev);
+	else
 		target_host->virt_boundary_mask = ~srp_dev->mr_page_mask;
 
 	target = host_to_target(target_host);