[PATCHv2 5/7] blk-mq-dma: move common dma start code to a helper

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

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

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 block/blk-mq-dma.c | 69 +++++++++++++++++++++++++---------------------
 1 file changed, 38 insertions(+), 31 deletions(-)

diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c
index 56158ed504747..1e2e93c1cf5e2 100644
--- a/block/blk-mq-dma.c
+++ b/block/blk-mq-dma.c
@@ -120,44 +120,16 @@ static bool blk_rq_dma_map_iova(struct request *req, struct device *dma_dev,
 	return true;
 }
 
-/**
- * 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;
 
 	iter->bio = req->bio;
-	iter->iter = req->bio->bi_iter;
 	memset(&iter->p2pdma, 0, sizeof(iter->p2pdma));
 	iter->status = BLK_STS_OK;
 
-	if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
-		iter->bvec = &req->special_vec;
-	else
-		iter->bvec = req->bio->bi_io_vec;
-
 	/*
 	 * Grab the first segment ASAP because we'll need it to check for P2P
 	 * transfers.
@@ -186,6 +158,41 @@ 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)
+{
+	iter->iter = req->bio->bi_iter;
+	if (req->rq_flags & RQF_SPECIAL_PAYLOAD)
+		iter->bvec = &req->special_vec;
+	else
+		iter->bvec = req->bio->bi_io_vec;
+
+	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);
 
 /**
-- 
2.47.1