block: add zoned BlockDriver check to block layer

Putting zoned/non-zoned BlockDrivers on top of each other is not
allowed.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20230508045533.175575-6-faithilikerun@gmail.com
Message-id: 20230324090605.28361-6-faithilikerun@gmail.com
[Adjust commit message prefix as suggested by Philippe Mathieu-Daudé
<philmd@linaro.org> and clarify that the check is about zoned
BlockDrivers.
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/block.c b/block.c
index dad9a4fa43..f04a6ad4e8 100644
--- a/block.c
+++ b/block.c
@@ -7982,6 +7982,25 @@ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
         return;
     }
 
+    /*
+     * Non-zoned block drivers do not follow zoned storage constraints
+     * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
+     * drivers in a graph.
+     */
+    if (!parent_bs->drv->supports_zoned_children &&
+        child_bs->bl.zoned == BLK_Z_HM) {
+        /*
+         * The host-aware model allows zoned storage constraints and random
+         * write. Allow mixing host-aware and non-zoned drivers. Using
+         * host-aware device as a regular device.
+         */
+        error_setg(errp, "Cannot add a %s child to a %s parent",
+                   child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
+                   parent_bs->drv->supports_zoned_children ?
+                   "support zoned children" : "not support zoned children");
+        return;
+    }
+
     if (!QLIST_EMPTY(&child_bs->parents)) {
         error_setg(errp, "The node %s already has a parent",
                    child_bs->node_name);