block-backend: Remember if attached device is non-qdev

Almost all block devices are qdevified by now. This allows us to go back
from the BlockBackend to the DeviceState. xen_disk is the last device
that is missing. We'll remember in the BlockBackend if a xen_disk is
attached and can then disable any features that require going from a BB
to the DeviceState.

While at it, clearly mark the function used by xen_disk as legacy even
in its name, not just in TODO comments.

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

3 files changed, 23 insertions, 11 deletions

diff --git a/block/block-backend.c b/block/block-backend.c
index 27ddacb..d97afa1 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -38,6 +38,7 @@ struct BlockBackend {
     BlockBackendPublic public;
 
     void *dev;                  /* attached device model, if any */
+    bool legacy_dev;            /* true if dev is not a DeviceState */
     /* TODO change to DeviceState when all users are qdevified */
     const BlockDevOps *dev_ops;
     void *dev_opaque;
@@ -506,32 +507,38 @@ void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs)
     }
 }
 
-/*
- * Attach device model @dev to @blk.
- * Return 0 on success, -EBUSY when a device model is attached already.
- */
-int blk_attach_dev(BlockBackend *blk, void *dev)
-/* TODO change to DeviceState *dev when all users are qdevified */
+static int blk_do_attach_dev(BlockBackend *blk, void *dev)
 {
     if (blk->dev) {
         return -EBUSY;
     }
     blk_ref(blk);
     blk->dev = dev;
+    blk->legacy_dev = false;
     blk_iostatus_reset(blk);
     return 0;
 }
 
 /*
  * Attach device model @dev to @blk.
+ * Return 0 on success, -EBUSY when a device model is attached already.
+ */
+int blk_attach_dev(BlockBackend *blk, DeviceState *dev)
+{
+    return blk_do_attach_dev(blk, dev);
+}
+
+/*
+ * Attach device model @dev to @blk.
  * @blk must not have a device model attached already.
  * TODO qdevified devices don't use this, remove when devices are qdevified
  */
-void blk_attach_dev_nofail(BlockBackend *blk, void *dev)
+void blk_attach_dev_legacy(BlockBackend *blk, void *dev)
 {
-    if (blk_attach_dev(blk, dev) < 0) {
+    if (blk_do_attach_dev(blk, dev) < 0) {
         abort();
     }
+    blk->legacy_dev = true;
 }
 
 /*
@@ -585,6 +592,11 @@ BlockBackend *blk_by_dev(void *dev)
 void blk_set_dev_ops(BlockBackend *blk, const BlockDevOps *ops,
                      void *opaque)
 {
+    /* All drivers that use blk_set_dev_ops() are qdevified and we want to keep
+     * it that way, so we can assume blk->dev is a DeviceState if blk->dev_ops
+     * is set. */
+    assert(!blk->legacy_dev);
+
     blk->dev_ops = ops;
     blk->dev_opaque = opaque;
 }
diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 5aa350a..1292a4b 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -1079,7 +1079,7 @@ static int blk_connect(struct XenDevice *xendev)
          * so we can blk_unref() unconditionally */
         blk_ref(blkdev->blk);
     }
-    blk_attach_dev_nofail(blkdev->blk, blkdev);
+    blk_attach_dev_legacy(blkdev->blk, blkdev);
     blkdev->file_size = blk_getlength(blkdev->blk);
     if (blkdev->file_size < 0) {
         BlockDriverState *bs = blk_bs(blkdev->blk);
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index a7993af..b07159b 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -107,8 +107,8 @@ BlockDeviceIoStatus blk_iostatus(const BlockBackend *blk);
 void blk_iostatus_disable(BlockBackend *blk);
 void blk_iostatus_reset(BlockBackend *blk);
 void blk_iostatus_set_err(BlockBackend *blk, int error);
-int blk_attach_dev(BlockBackend *blk, void *dev);
-void blk_attach_dev_nofail(BlockBackend *blk, void *dev);
+int blk_attach_dev(BlockBackend *blk, DeviceState *dev);
+void blk_attach_dev_legacy(BlockBackend *blk, void *dev);
 void blk_detach_dev(BlockBackend *blk, void *dev);
 void *blk_get_attached_dev(BlockBackend *blk);
 BlockBackend *blk_by_dev(void *dev);