[PATCH v5 8/8] nvdimm: virtio_pmem: drain requests in freeze

[Li Chen <me@linux.beauty>]

virtio_pmem_freeze() currently deletes virtqueues and resets the device
without waking threads waiting for a virtqueue descriptor or a host
completion.

Mark the request virtqueue broken before reset. This makes new submissions
fail fast and lets -ENOSPC waiters leave the wait list. Reset the device
before draining used and unused request tokens, then delete the virtqueues.
This wakes waiters with -EIO. It also keeps the detach call on a quiesced
device.

Signed-off-by: Li Chen <me@linux.beauty>
---
Changes in v5:
- Reset the device before draining used and unused request tokens.
- Use the split broken-marking and post-reset drain helpers.
v2->v3:
- No change.
v3->v4:
- Rebased onto v7.1-rc7 and renumbered after the flush error patches.

 drivers/nvdimm/virtio_pmem.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c
index 3bcc7b3671d21..9961bc2678d0f 100644
--- a/drivers/nvdimm/virtio_pmem.c
+++ b/drivers/nvdimm/virtio_pmem.c
@@ -158,9 +158,21 @@ static void virtio_pmem_remove(struct virtio_device *vdev)
 
 static int virtio_pmem_freeze(struct virtio_device *vdev)
 {
-	vdev->config->del_vqs(vdev);
+	struct virtio_pmem *vpmem = vdev->priv;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vpmem->pmem_lock, flags);
+	virtio_pmem_mark_broken(vpmem);
+	spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
+
 	virtio_reset_device(vdev);
 
+	spin_lock_irqsave(&vpmem->pmem_lock, flags);
+	virtio_pmem_drain(vpmem);
+	spin_unlock_irqrestore(&vpmem->pmem_lock, flags);
+
+	vdev->config->del_vqs(vdev);
+
 	return 0;
 }
 
-- 
2.52.0