[PATCH v2 RFC 2/3] virtio_blk: add virtblk_notify() as virtio_driver's notify() callback

[Heinz Graalfs <graalfs@linux.vnet.ibm.com>]

Add virtblk_notify() as virtio_driver's notify() callback.

When a transport driver is notified that a device disappeared it
should invoke this callback to prevent further request queueing.

Subsequent block layer calls of virtio_blk's request function will
fail, resulting in appropriate I/O errors.

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
---
 drivers/block/virtio_blk.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 2d43be4..04fd635 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -11,6 +11,7 @@
 #include <linux/string_helpers.h>
 #include <scsi/scsi_cmnd.h>
 #include <linux/idr.h>
+#include <linux/notifier.h>
 
 #define PART_BITS 4
 
@@ -901,6 +902,21 @@ static void virtblk_remove(struct virtio_device *vdev)
 		ida_simple_remove(&vd_index_ida, index);
 }
 
+static int virtblk_notify(struct virtio_device *vdev, int event)
+{
+	struct virtio_blk *vblk = vdev->priv;
+	unsigned long flags;
+
+	if (event == VDEV_GONE) {
+		spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
+		queue_flag_set(QUEUE_FLAG_DYING, vblk->disk->queue);
+		queue_flag_set(QUEUE_FLAG_NOMERGES, vblk->disk->queue);
+		queue_flag_set(QUEUE_FLAG_NOXMERGES, vblk->disk->queue);
+		spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
+	}
+	return NOTIFY_DONE;
+}
+
 #ifdef CONFIG_PM
 static int virtblk_freeze(struct virtio_device *vdev)
 {
@@ -961,6 +977,7 @@ static struct virtio_driver virtio_blk = {
 	.probe			= virtblk_probe,
 	.remove			= virtblk_remove,
 	.config_changed		= virtblk_config_changed,
+	.notify			= virtblk_notify,
 #ifdef CONFIG_PM
 	.freeze			= virtblk_freeze,
 	.restore		= virtblk_restore,
-- 
1.8.3.1