[PATCH v3 06/10] block: forward create_dmabuf_token to drivers

[Pavel Begunkov <asml.silence@gmail.com>]

Add a trivial implementation of the create_dmabuf_token call for
block devices that forwards the call to a new blk-mq callback if it's
available.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 block/fops.c           | 14 ++++++++++++++
 include/linux/blk-mq.h |  9 +++++++++
 2 files changed, 23 insertions(+)

diff --git a/block/fops.c b/block/fops.c
index 713a3ba3f457..3d8a48a7d645 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -951,6 +951,19 @@ static int blkdev_mmap_prepare(struct vm_area_desc *desc)
 	return generic_file_mmap_prepare(desc);
 }
 
+static int blkdev_create_dmabuf_token(struct file *file,
+				      struct io_dmabuf_token *token)
+{
+	struct request_queue *q = bdev_get_queue(file_bdev(file));
+
+	if (!(file->f_flags & O_DIRECT))
+		return -EINVAL;
+	if (!q->mq_ops || !q->mq_ops->create_dmabuf_token)
+		return -EINVAL;
+
+	return q->mq_ops->create_dmabuf_token(q, token);
+}
+
 const struct file_operations def_blk_fops = {
 	.open		= blkdev_open,
 	.release	= blkdev_release,
@@ -969,6 +982,7 @@ const struct file_operations def_blk_fops = {
 	.fallocate	= blkdev_fallocate,
 	.uring_cmd	= blkdev_uring_cmd,
 	.fop_flags	= FOP_BUFFER_RASYNC,
+	.create_dmabuf_token = blkdev_create_dmabuf_token,
 };
 
 static __init int blkdev_init(void)
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 18a2388ba581..ee31fb3ada10 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -15,6 +15,8 @@ struct blk_mq_tags;
 struct blk_flush_queue;
 struct io_comp_batch;
 
+struct io_dmabuf_token;
+
 #define BLKDEV_MIN_RQ	4
 #define BLKDEV_DEFAULT_RQ	128
 
@@ -684,6 +686,13 @@ struct blk_mq_ops {
 	 */
 	void (*show_rq)(struct seq_file *m, struct request *rq);
 #endif
+
+	/**
+	 * @create_dma_token: Create a dma token, which will be using to map
+	 * a dmabuf for IO requests.
+	 */
+	int (*create_dmabuf_token)(struct request_queue *,
+				   struct io_dmabuf_token *token);
 };
 
 /* Keep hctx_flag_name[] in sync with the definitions below */
-- 
2.53.0