Linux Virtualization - Jun 2016 - [PATCH] drivers: virtio_blk: notify blk-core when hw-queue number changes

A guest might be migrated to other hosts with different num_queues, the
blk-core should aware of that else the reference of &vblk->vqs[qid] may
be wrong.

Signed-off-by: Bob Liu <bob.liu at oracle.com>
---
 drivers/block/virtio_blk.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 42758b5..c169238 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -819,6 +819,9 @@ static int virtblk_restore(struct virtio_device *vdev)
 	if (ret)
 		return ret;
 
+	if (vblk->num_vqs != vblk->tag_set.nr_hw_queues)
+		blk_mq_update_nr_hw_queues(&vblk->tag_set, vblk->num_vqs);
+
 	virtio_device_ready(vdev);
 
 	blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
-- 
2.7.4