From: Keith Busch <kbusch@xxxxxxxxxx>
The same buffer may be used for many subsequent IO's. Instead of setting
up the mapping per-IO, provide an interface that can allow a buffer to be
premapped just once and referenced again later.
Signed-off-by: Keith Busch <kbusch@xxxxxxxxxx>
---
block/bdev.c | 20 ++++++++++++++++++++
include/linux/blk-mq.h | 13 +++++++++++++
include/linux/blkdev.h | 16 ++++++++++++++++
3 files changed, 49 insertions(+)
diff --git a/block/bdev.c b/block/bdev.c
index ce05175e71ce..345176e12bb1 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -1069,3 +1069,23 @@ void sync_bdevs(bool wait)
spin_unlock(&blockdev_superblock->s_inode_list_lock);
iput(old_inode);
}
+
+#ifdef CONFIG_HAS_DMA
+void *block_dma_map(struct block_device *bdev, struct bio_vec *bvec,
+ int nr_vecs)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ if (q->mq_ops && q->mq_ops->dma_map)
+ return q->mq_ops->dma_map(q, bvec, nr_vecs);
+ return ERR_PTR(-EINVAL);
+}
+
+void block_dma_unmap(struct block_device *bdev, void *dma_tag)
+{
+ struct request_queue *q = bdev_get_queue(bdev);
+
+ if (q->mq_ops && q->mq_ops->dma_unmap)
+ return q->mq_ops->dma_unmap(q, dma_tag);
+}
+#endif
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index effee1dc715a..e10aabb36c2c 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -639,6 +639,19 @@ struct blk_mq_ops {
*/
void (*show_rq)(struct seq_file *m, struct request *rq);
#endif
+
+#ifdef CONFIG_HAS_DMA
+ /**
+ * @dma_map: Create a dma mapping. On success, returns an opaque cookie
+ * that the can be referenced by the driver in future requests.
+ */
+ void *(*dma_map)(struct request_queue *q, struct bio_vec *bvec, int nr_vecs);
+
+ /**
+ * @dma_unmap: Tear down a previously created dma mapping.
+ */
+ void (*dma_unmap)(struct request_queue *q, void *dma_tag);
+#endif
};
enum {
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d04bdf549efa..47f7f6f430d9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1526,4 +1526,20 @@ struct io_comp_batch {
#define DEFINE_IO_COMP_BATCH(name) struct io_comp_batch name = { }
+#ifdef CONFIG_HAS_DMA
+void *block_dma_map(struct block_device *bdev, struct bio_vec *bvec,
+ int nr_vecs);
+void block_dma_unmap(struct block_device *bdev, void *dma_tag);
+#else
+static inline void *block_dma_map(struct block_device *bdev,
+ struct bio_vec *bvec, int nr_vecs)
+{
+ return ERR_PTR(-ENOTSUPP);
+}
+
+static inline void block_dma_unmap(struct block_device *bdev, void *dma_tag)
+{
+}
+#endif
+
#endif /* _LINUX_BLKDEV_H */
--
2.30.2
