blk-mq-dma: move common dma start code to a helper

In preparing for dma mapping integrity metadata, move the common dma
setup to a helper.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20250813153153.3260897-6-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 33 insertions, 26 deletions

diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c
index 58defab21882..31dd8f58f081 100644
--- a/block/blk-mq-dma.c
+++ b/block/blk-mq-dma.c
@@ -141,35 +141,12 @@ static inline void blk_rq_map_iter_init(struct request *rq,
 	}
 }
 
-/**
- * blk_rq_dma_map_iter_start - map the first DMA segment for a request
- * @req:	request to map
- * @dma_dev:	device to map to
- * @state:	DMA IOVA state
- * @iter:	block layer DMA iterator
- *
- * Start DMA mapping @req to @dma_dev.  @state and @iter are provided by the
- * caller and don't need to be initialized.  @state needs to be stored for use
- * at unmap time, @iter is only needed at map time.
- *
- * Returns %false if there is no segment to map, including due to an error, or
- * %true ft it did map a segment.
- *
- * If a segment was mapped, the DMA address for it is returned in @iter.addr and
- * the length in @iter.len.  If no segment was mapped the status code is
- * returned in @iter.status.
- *
- * The caller can call blk_rq_dma_map_coalesce() to check if further segments
- * need to be mapped after this, or go straight to blk_rq_dma_map_iter_next()
- * to try to map the following segments.
- */
-bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev,
-		struct dma_iova_state *state, struct blk_dma_iter *iter)
+static bool blk_dma_map_iter_start(struct request *req, struct device *dma_dev,
+		struct dma_iova_state *state, struct blk_dma_iter *iter,
+		unsigned int total_len)
 {
-	unsigned int total_len = blk_rq_payload_bytes(req);
 	struct phys_vec vec;
 
-	blk_rq_map_iter_init(req, &iter->iter);
 	memset(&iter->p2pdma, 0, sizeof(iter->p2pdma));
 	iter->status = BLK_STS_OK;
 
@@ -201,6 +178,36 @@ bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev,
 		return blk_rq_dma_map_iova(req, dma_dev, state, iter, &vec);
 	return blk_dma_map_direct(req, dma_dev, iter, &vec);
 }
+
+/**
+ * blk_rq_dma_map_iter_start - map the first DMA segment for a request
+ * @req:	request to map
+ * @dma_dev:	device to map to
+ * @state:	DMA IOVA state
+ * @iter:	block layer DMA iterator
+ *
+ * Start DMA mapping @req to @dma_dev.  @state and @iter are provided by the
+ * caller and don't need to be initialized.  @state needs to be stored for use
+ * at unmap time, @iter is only needed at map time.
+ *
+ * Returns %false if there is no segment to map, including due to an error, or
+ * %true ft it did map a segment.
+ *
+ * If a segment was mapped, the DMA address for it is returned in @iter.addr and
+ * the length in @iter.len.  If no segment was mapped the status code is
+ * returned in @iter.status.
+ *
+ * The caller can call blk_rq_dma_map_coalesce() to check if further segments
+ * need to be mapped after this, or go straight to blk_rq_dma_map_iter_next()
+ * to try to map the following segments.
+ */
+bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev,
+		struct dma_iova_state *state, struct blk_dma_iter *iter)
+{
+	blk_rq_map_iter_init(req, &iter->iter);
+	return blk_dma_map_iter_start(req, dma_dev, state, iter,
+				      blk_rq_payload_bytes(req));
+}
 EXPORT_SYMBOL_GPL(blk_rq_dma_map_iter_start);
 
 /**