[RFC v5 07/11] config: add check to block layer

[Sam Li <faithilikerun@gmail.com>]

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

Signed-off-by: Sam Li <faithilikerun@gmail.com>
---
 block.c                          | 13 +++++++++++++
 block/file-posix.c               |  2 ++
 block/raw-format.c               |  1 +
 include/block/block_int-common.h | 10 ++++++++++
 4 files changed, 26 insertions(+)

diff --git a/block.c b/block.c
index bc85f46eed..8a259b158c 100644
--- a/block.c
+++ b/block.c
@@ -7947,6 +7947,19 @@ 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->drv->is_zoned) {
+        error_setg(errp, "Cannot add a %s child to a %s parent",
+                   child_bs->drv->is_zoned ? "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);
diff --git a/block/file-posix.c b/block/file-posix.c
index 6c045eb6e8..8eb0b7bc9b 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -4023,6 +4023,8 @@ static BlockDriver bdrv_zoned_host_device = {
         .format_name = "zoned_host_device",
         .protocol_name = "zoned_host_device",
         .instance_size = sizeof(BDRVRawState),
+        .is_zoned = true,
+        .supports_zoned_children = true,
         .bdrv_needs_filename = true,
         .bdrv_probe_device  = hdev_probe_device,
         .bdrv_parse_filename = zoned_host_device_parse_filename,
diff --git a/block/raw-format.c b/block/raw-format.c
index 6b20bd22ef..9441536819 100644
--- a/block/raw-format.c
+++ b/block/raw-format.c
@@ -614,6 +614,7 @@ static void raw_child_perm(BlockDriverState *bs, BdrvChild *c,
 BlockDriver bdrv_raw = {
     .format_name          = "raw",
     .instance_size        = sizeof(BDRVRawState),
+    .supports_zoned_children = true,
     .bdrv_probe           = &raw_probe,
     .bdrv_reopen_prepare  = &raw_reopen_prepare,
     .bdrv_reopen_commit   = &raw_reopen_commit,
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index de44c7b6f4..0476cd0491 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -126,6 +126,16 @@ struct BlockDriver {
      */
     bool is_format;
 
+    /*
+     * Set to true if the BlockDriver is a zoned block driver.
+     */
+    bool is_zoned;
+
+    /*
+     * Set to true if the BlockDriver supports zoned children.
+     */
+    bool supports_zoned_children;
+
     /*
      * Drivers not implementing bdrv_parse_filename nor bdrv_open should have
      * this field set to true, except ones that are defined only by their
-- 
2.37.1