virtio-scsi: Catch BDS-BB removal/insertion

Make use of the BDS-BB removal and insertion notifiers to remove or set
up, respectively, virtio-scsi's op blockers.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/scsi/virtio-scsi.c

@@ -758,6 +758,22 @@ static void virtio_scsi_change(SCSIBus *bus, SCSIDevice *dev, SCSISense sense)
     }
 }
 
+static void virtio_scsi_blk_insert_notifier(Notifier *n, void *data)
+{
+    VirtIOSCSIBlkChangeNotifier *cn = DO_UPCAST(VirtIOSCSIBlkChangeNotifier,
+                                                n, n);
+    assert(cn->sd->conf.blk == data);
+    blk_op_block_all(cn->sd->conf.blk, cn->s->blocker);
+}
+
+static void virtio_scsi_blk_remove_notifier(Notifier *n, void *data)
+{
+    VirtIOSCSIBlkChangeNotifier *cn = DO_UPCAST(VirtIOSCSIBlkChangeNotifier,
+                                                n, n);
+    assert(cn->sd->conf.blk == data);
+    blk_op_unblock_all(cn->sd->conf.blk, cn->s->blocker);
+}
+
 static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
                                 Error **errp)
 {
@@ -766,6 +782,8 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     SCSIDevice *sd = SCSI_DEVICE(dev);
 
     if (s->ctx && !s->dataplane_disabled) {
+        VirtIOSCSIBlkChangeNotifier *insert_notifier, *remove_notifier;
+
         if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
             return;
         }
@@ -773,6 +791,20 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
         aio_context_acquire(s->ctx);
         blk_set_aio_context(sd->conf.blk, s->ctx);
         aio_context_release(s->ctx);
+
+        insert_notifier = g_new0(VirtIOSCSIBlkChangeNotifier, 1);
+        insert_notifier->n.notify = virtio_scsi_blk_insert_notifier;
+        insert_notifier->s = s;
+        insert_notifier->sd = sd;
+        blk_add_insert_bs_notifier(sd->conf.blk, &insert_notifier->n);
+        QTAILQ_INSERT_TAIL(&s->insert_notifiers, insert_notifier, next);
+
+        remove_notifier = g_new0(VirtIOSCSIBlkChangeNotifier, 1);
+        remove_notifier->n.notify = virtio_scsi_blk_remove_notifier;
+        remove_notifier->s = s;
+        remove_notifier->sd = sd;
+        blk_add_remove_bs_notifier(sd->conf.blk, &remove_notifier->n);
+        QTAILQ_INSERT_TAIL(&s->remove_notifiers, remove_notifier, next);
     }
 
     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
@@ -788,6 +820,7 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
     SCSIDevice *sd = SCSI_DEVICE(dev);
+    VirtIOSCSIBlkChangeNotifier *insert_notifier, *remove_notifier;
 
     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
         virtio_scsi_push_event(s, sd,
@@ -798,6 +831,25 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     if (s->ctx) {
         blk_op_unblock_all(sd->conf.blk, s->blocker);
     }
+
+    QTAILQ_FOREACH(insert_notifier, &s->insert_notifiers, next) {
+        if (insert_notifier->sd == sd) {
+            notifier_remove(&insert_notifier->n);
+            QTAILQ_REMOVE(&s->insert_notifiers, insert_notifier, next);
+            g_free(insert_notifier);
+            break;
+        }
+    }
+
+    QTAILQ_FOREACH(remove_notifier, &s->remove_notifiers, next) {
+        if (remove_notifier->sd == sd) {
+            notifier_remove(&remove_notifier->n);
+            QTAILQ_REMOVE(&s->remove_notifiers, remove_notifier, next);
+            g_free(remove_notifier);
+            break;
+        }
+    }
+
     qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
 }
 
@@ -912,6 +964,9 @@ static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
     add_migration_state_change_notifier(&s->migration_state_notifier);
 
     error_setg(&s->blocker, "block device is in use by data plane");
+
+    QTAILQ_INIT(&s->insert_notifiers);
+    QTAILQ_INIT(&s->remove_notifiers);
 }
 
 static void virtio_scsi_instance_init(Object *obj)

include/hw/virtio/virtio-scsi.h

@@ -76,6 +76,13 @@ typedef struct VirtIOSCSICommon {
     VirtQueue **cmd_vqs;
 } VirtIOSCSICommon;
 
+typedef struct VirtIOSCSIBlkChangeNotifier {
+    Notifier n;
+    struct VirtIOSCSI *s;
+    SCSIDevice *sd;
+    QTAILQ_ENTRY(VirtIOSCSIBlkChangeNotifier) next;
+} VirtIOSCSIBlkChangeNotifier;
+
 typedef struct VirtIOSCSI {
     VirtIOSCSICommon parent_obj;
 
@@ -86,6 +93,9 @@ typedef struct VirtIOSCSI {
     /* Fields for dataplane below */
     AioContext *ctx; /* one iothread per virtio-scsi-pci for now */
 
+    QTAILQ_HEAD(, VirtIOSCSIBlkChangeNotifier) insert_notifiers;
+    QTAILQ_HEAD(, VirtIOSCSIBlkChangeNotifier) remove_notifiers;
+
     /* Vring is used instead of vq in dataplane code, because of the underlying
      * memory layer thread safety */
     VirtIOSCSIVring *ctrl_vring;