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Subject[PATCH 2/2] virtio-scsi: support online resizing of disks
Date
Support the LUN parameter change event.  Currently, the host fires this event
when the capacity of a disk is changed from the virtual machine monitor.
The resize then appears in the kernel log like this:

sd 0:0:0:0: [sda] 46137344 512-byte logical blocks: (23.6 GB/22.0 GIb)
sda: detected capacity change from 22548578304 to 23622320128

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
drivers/scsi/virtio_scsi.c | 31 ++++++++++++++++++++++++++++++-
include/linux/virtio_scsi.h | 2 ++
2 files changed, 32 insertions(+), 1 deletions(-)

diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c
index c937232..d8c6a57 100644
--- a/drivers/scsi/virtio_scsi.c
+++ b/drivers/scsi/virtio_scsi.c
@@ -285,6 +285,31 @@ static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi,
}
}

+static void virtscsi_handle_param_change(struct virtio_scsi *vscsi,
+ struct virtio_scsi_event *event)
+{
+ struct scsi_device *sdev;
+ struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev);
+ unsigned int target = event->lun[1];
+ unsigned int lun = virtscsi_get_lun(event->lun);
+ u8 asc = event->reason & 255;
+ u8 ascq = event->reason >> 8;
+
+ sdev = scsi_device_lookup(shost, 0, target, lun);
+ if (!sdev) {
+ pr_err("SCSI device %d 0 %d %d not found\n",
+ shost->host_no, target, lun);
+ return;
+ }
+
+ /* Handle "Parameters changed", "Mode parameters changed", and
+ "Capacity data has changed". */
+ if (asc == 0x2a && (ascq == 0x00 || ascq == 0x01 || ascq == 0x09))
+ scsi_rescan_device(&sdev->sdev_gendev);
+
+ scsi_device_put(sdev);
+}
+
static void virtscsi_handle_event(struct work_struct *work)
{
struct virtio_scsi_event_node *event_node =
@@ -303,6 +328,9 @@ static void virtscsi_handle_event(struct work_struct *work)
case VIRTIO_SCSI_T_TRANSPORT_RESET:
virtscsi_handle_transport_reset(vscsi, event);
break;
+ case VIRTIO_SCSI_T_PARAM_CHANGE:
+ virtscsi_handle_param_change(vscsi, event);
+ break;
default:
pr_err("Unsupport virtio scsi event %x\n", event->event);
}
@@ -739,7 +767,8 @@ static struct virtio_device_id id_table[] = {
};

static unsigned int features[] = {
- VIRTIO_SCSI_F_HOTPLUG
+ VIRTIO_SCSI_F_HOTPLUG,
+ VIRTIO_SCSI_F_CHANGE,
};

static struct virtio_driver virtio_scsi_driver = {
diff --git a/include/linux/virtio_scsi.h b/include/linux/virtio_scsi.h
index dc8d305..d6b4440 100644
--- a/include/linux/virtio_scsi.h
+++ b/include/linux/virtio_scsi.h
@@ -72,6 +72,7 @@ struct virtio_scsi_config {
/* Feature Bits */
#define VIRTIO_SCSI_F_INOUT 0
#define VIRTIO_SCSI_F_HOTPLUG 1
+#define VIRTIO_SCSI_F_CHANGE 2

/* Response codes */
#define VIRTIO_SCSI_S_OK 0
@@ -108,6 +109,7 @@ struct virtio_scsi_config {
#define VIRTIO_SCSI_T_NO_EVENT 0
#define VIRTIO_SCSI_T_TRANSPORT_RESET 1
#define VIRTIO_SCSI_T_ASYNC_NOTIFY 2
+#define VIRTIO_SCSI_T_PARAM_CHANGE 3

/* Reasons of transport reset event */
#define VIRTIO_SCSI_EVT_RESET_HARD 0
--
1.7.1


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