[PATCH v2 2/2] virtio-blk: mark disk dead on ERS permanent failure

After ERS reports pci_channel_io_perm_failure, virtio-pci must ask the
virtio driver to tear down the block device, not only mark virtqueues
broken.  Call the virtio driver shutdown hook from virtio-pci on
perm_failure; virtio-blk implements shutdown with blk_mark_disk_dead().

Fail new requests early in virtio_queue_rq when virtqueues were removed
during frozen reset_prepare (vqs == NULL).  A broken vq already fails in
virtqueue_add; no separate disk_live() check is needed.

Assisted-by: DeepSeek:deepseek-v3
Signed-off-by: Xixin Liu <[email protected]>
---
 drivers/block/virtio_blk.c         | 31 ++++++++++++++++++++++++++++++
 drivers/virtio/virtio_pci_common.c | 10 +++++++++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 32bf3ba07a9d..fda2d4f3c7c6 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -435,6 +435,12 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
 	blk_status_t status;
 	int err;
 
+	/* VQs may be gone after frozen reset_prepare; avoid NULL deref. */
+	if (unlikely(!vblk->vqs || !vblk->vdev)) {
+		blk_mq_start_request(req);
+		return BLK_STS_IOERR;
+	}
+
 	status = virtblk_prep_rq(hctx, vblk, req, vbr);
 	if (unlikely(status))
 		return status;
@@ -1561,6 +1567,30 @@ static int virtblk_probe(struct virtio_device *vdev)
 	return err;
 }
 
+
+/* Stop I/O and mark the gendisk dead (ERS perm_failure or system shutdown). */
+static void virtblk_shutdown(struct virtio_device *vdev)
+{
+	struct virtio_blk *vblk = vdev->priv;
+	struct request_queue *q;
+	unsigned int memflags;
+
+	if (!vblk || !vblk->disk)
+		return;
+
+	virtio_break_device(vdev);
+	flush_work(&vblk->config_work);
+
+	q = vblk->disk->queue;
+	memflags = blk_mq_freeze_queue(q);
+	blk_mq_quiesce_queue_nowait(q);
+
+	blk_mark_disk_dead(vblk->disk);
+
+	blk_mq_unquiesce_queue(q);
+	blk_mq_unfreeze_queue(q, memflags);
+}
+
 static void virtblk_remove(struct virtio_device *vdev)
 {
 	struct virtio_blk *vblk = vdev->priv;
@@ -1684,6 +1714,7 @@ static struct virtio_driver virtio_blk = {
 	.probe				= virtblk_probe,
 	.remove				= virtblk_remove,
 	.config_changed			= virtblk_config_changed,
+	.shutdown			= virtblk_shutdown,
 #ifdef CONFIG_PM_SLEEP
 	.freeze				= virtblk_freeze,
 	.restore			= virtblk_restore,
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index fff6b6e2d0c5..957b3282865c 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -849,7 +849,15 @@ static pci_ers_result_t virtio_pci_error_detected(struct pci_dev *pci_dev,
 	case pci_channel_io_perm_failure:
 		dev_warn(&pci_dev->dev,
 			 "permanent failure, disconnecting device\n");
-		virtio_break_device(&vp_dev->vdev);
+		{
+			struct virtio_driver *drv =
+				drv_to_virtio(vp_dev->vdev.dev.driver);
+
+			if (drv && drv->shutdown)
+				drv->shutdown(&vp_dev->vdev);
+			else
+				virtio_break_device(&vp_dev->vdev);
+		}
 		return PCI_ERS_RESULT_DISCONNECT;
 	default:
 		break;
-- 
2.43.0