blk-mq: split out tag initialization, support shared tags

Add a new blk_mq_tag_set structure that gets set up before we initialize
the queue.  A single blk_mq_tag_set structure can be shared by multiple
queues.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Modular export of blk_mq_{alloc,free}_tagset added by me.

Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 31 insertions, 17 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index d06206abd340..f909a8821e65 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -30,6 +30,9 @@ struct virtio_blk
 	/* The disk structure for the kernel. */
 	struct gendisk *disk;
 
+	/* Block layer tags. */
+	struct blk_mq_tag_set tag_set;
+
 	/* Process context for config space updates */
 	struct work_struct config_work;
 
@@ -480,8 +483,9 @@ static const struct device_attribute dev_attr_cache_type_rw =
 	__ATTR(cache_type, S_IRUGO|S_IWUSR,
 	       virtblk_cache_type_show, virtblk_cache_type_store);
 
-static int virtblk_init_request(void *data, struct blk_mq_hw_ctx *hctx,
-		struct request *rq, unsigned int nr)
+static int virtblk_init_request(void *data, struct request *rq,
+		unsigned int hctx_idx, unsigned int request_idx,
+		unsigned int numa_node)
 {
 	struct virtio_blk *vblk = data;
 	struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq);
@@ -495,18 +499,12 @@ static struct blk_mq_ops virtio_mq_ops = {
 	.map_queue	= blk_mq_map_queue,
 	.alloc_hctx	= blk_mq_alloc_single_hw_queue,
 	.free_hctx	= blk_mq_free_single_hw_queue,
-	.init_request	= virtblk_init_request,
 	.complete	= virtblk_request_done,
+	.init_request	= virtblk_init_request,
 };
 
-static struct blk_mq_reg virtio_mq_reg = {
-	.ops		= &virtio_mq_ops,
-	.nr_hw_queues	= 1,
-	.queue_depth	= 0, /* Set in virtblk_probe */
-	.numa_node	= NUMA_NO_NODE,
-	.flags		= BLK_MQ_F_SHOULD_MERGE,
-};
-module_param_named(queue_depth, virtio_mq_reg.queue_depth, uint, 0444);
+static unsigned int virtblk_queue_depth;
+module_param_named(queue_depth, virtblk_queue_depth, uint, 0444);
 
 static int virtblk_probe(struct virtio_device *vdev)
 {
@@ -562,20 +560,32 @@ static int virtblk_probe(struct virtio_device *vdev)
 	}
 
 	/* Default queue sizing is to fill the ring. */
-	if (!virtio_mq_reg.queue_depth) {
-		virtio_mq_reg.queue_depth = vblk->vq->num_free;
+	if (!virtblk_queue_depth) {
+		virtblk_queue_depth = vblk->vq->num_free;
 		/* ... but without indirect descs, we use 2 descs per req */
 		if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
-			virtio_mq_reg.queue_depth /= 2;
+			virtblk_queue_depth /= 2;
 	}
-	virtio_mq_reg.cmd_size =
+
+	memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
+	vblk->tag_set.ops = &virtio_mq_ops;
+	vblk->tag_set.nr_hw_queues = 1;
+	vblk->tag_set.queue_depth = virtblk_queue_depth;
+	vblk->tag_set.numa_node = NUMA_NO_NODE;
+	vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+	vblk->tag_set.cmd_size =
 		sizeof(struct virtblk_req) +
 		sizeof(struct scatterlist) * sg_elems;
+	vblk->tag_set.driver_data = vblk;
 
-	q = vblk->disk->queue = blk_mq_init_queue(&virtio_mq_reg, vblk);
+	err = blk_mq_alloc_tag_set(&vblk->tag_set);
+	if (err)
+		goto out_put_disk;
+
+	q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
 	if (!q) {
 		err = -ENOMEM;
-		goto out_put_disk;
+		goto out_free_tags;
 	}
 
 	q->queuedata = vblk;
@@ -678,6 +688,8 @@ static int virtblk_probe(struct virtio_device *vdev)
 out_del_disk:
 	del_gendisk(vblk->disk);
 	blk_cleanup_queue(vblk->disk->queue);
+out_free_tags:
+	blk_mq_free_tag_set(&vblk->tag_set);
 out_put_disk:
 	put_disk(vblk->disk);
 out_free_vq:
@@ -704,6 +716,8 @@ static void virtblk_remove(struct virtio_device *vdev)
 	del_gendisk(vblk->disk);
 	blk_cleanup_queue(vblk->disk->queue);
 
+	blk_mq_free_tag_set(&vblk->tag_set);
+
 	/* Stop all the virtqueues. */
 	vdev->config->reset(vdev);