block: add dma_map_bvec helper

fix #29327388

commit 3ab3a0313cb8c50391d74e40fd46a3408d8e4de9 upstream

Provide a nice little shortcut for mapping a single bvec.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NSagi Grimberg <sagi@grimberg.me>
Reviewed-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: NJoseph Qi <joseph.qi@linux.alibaba.com>

include/linux/blkdev.h

@@ -794,6 +794,10 @@ static inline bool blk_account_rq(struct request *rq)
 #define rq_dma_dir(rq) \
 	(op_is_write(req_op(rq)) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
 
+#define dma_map_bvec(dev, bv, dir, attrs) \
+	dma_map_page_attrs(dev, (bv)->bv_page, (bv)->bv_offset, (bv)->bv_len, \
+	(dir), (attrs))
+
 /*
  * Driver can handle struct request, if it either has an old style
  * request_fn defined, or is blk-mq based.