[RFC 4/7] scsi_lib_dma: Add _attrs variant of scsi_dma_map()

[mhkelley58@gmail.com]

From: Michael Kelley <mhklinux@outlook.com>

Extend the SCSI DMA mapping interfaces by adding the "_attrs" variant
of scsi_dma_map(). This variant allows passing DMA_ATTR_* values, such
as is needed to support swiotlb throttling. The existing scsi_dma_map()
interface is unchanged, so no incompatibilities are introduced.

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
---
 drivers/scsi/scsi_lib_dma.c | 13 +++++++------
 include/scsi/scsi_cmnd.h    |  7 +++++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/scsi_lib_dma.c b/drivers/scsi/scsi_lib_dma.c
index 5723915275ad..34453a79be97 100644
--- a/drivers/scsi/scsi_lib_dma.c
+++ b/drivers/scsi/scsi_lib_dma.c
@@ -14,30 +14,31 @@
 #include <scsi/scsi_host.h>
 
 /**
- * scsi_dma_map - perform DMA mapping against command's sg lists
+ * scsi_dma_map_attrs - perform DMA mapping against command's sg lists
  * @cmd:	scsi command
+ * @attrs:	DMA attribute flags
  *
  * Returns the number of sg lists actually used, zero if the sg lists
  * is NULL, or -ENOMEM if the mapping failed.
  */
-int scsi_dma_map(struct scsi_cmnd *cmd)
+int scsi_dma_map_attrs(struct scsi_cmnd *cmd, unsigned long attrs)
 {
 	int nseg = 0;
 
 	if (scsi_sg_count(cmd)) {
 		struct device *dev = cmd->device->host->dma_dev;
 
-		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
-				  cmd->sc_data_direction);
+		nseg = dma_map_sg_attrs(dev, scsi_sglist(cmd),
+			scsi_sg_count(cmd), cmd->sc_data_direction, attrs);
 		if (unlikely(!nseg))
 			return -ENOMEM;
 	}
 	return nseg;
 }
-EXPORT_SYMBOL(scsi_dma_map);
+EXPORT_SYMBOL(scsi_dma_map_attrs);
 
 /**
- * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map
+ * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map_attrs
  * @cmd:	scsi command
  */
 void scsi_dma_unmap(struct scsi_cmnd *cmd)
diff --git a/include/scsi/scsi_cmnd.h b/include/scsi/scsi_cmnd.h
index 45c40d200154..6603003bc588 100644
--- a/include/scsi/scsi_cmnd.h
+++ b/include/scsi/scsi_cmnd.h
@@ -170,11 +170,14 @@ extern void scsi_kunmap_atomic_sg(void *virt);
 blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd);
 void scsi_free_sgtables(struct scsi_cmnd *cmd);
 
+#define scsi_dma_map(cmd) scsi_dma_map_attrs(cmd, 0)
+
 #ifdef CONFIG_SCSI_DMA
-extern int scsi_dma_map(struct scsi_cmnd *cmd);
+extern int scsi_dma_map_attrs(struct scsi_cmnd *cmd, unsigned long attrs);
 extern void scsi_dma_unmap(struct scsi_cmnd *cmd);
 #else /* !CONFIG_SCSI_DMA */
-static inline int scsi_dma_map(struct scsi_cmnd *cmd) { return -ENOSYS; }
+static inline int scsi_dma_map_attrs(struct scsi_cmnd *cmd, unsigned long attrs)
+						{ return -ENOSYS; }
 static inline void scsi_dma_unmap(struct scsi_cmnd *cmd) { }
 #endif /* !CONFIG_SCSI_DMA */
 
-- 
2.25.1