We will calculate the required new permissions in the prepare stage of a
reopen. Required permissions of children can be influenced by the
changes made to their parents, but parents are independent from their
children. This means that permissions need to be calculated top-down. In
order to achieve this, queue parents before their children rather than
queuing the children first.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/block.c b/block.c
index ed8d51dd42..204cbb46c7 100644
--- a/block.c
+++ b/block.c
@@ -2768,6 +2768,19 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
         flags |= BDRV_O_ALLOW_RDWR;
     }
 
+    if (!bs_entry) {
+        bs_entry = g_new0(BlockReopenQueueEntry, 1);
+        QSIMPLEQ_INSERT_TAIL(bs_queue, bs_entry, entry);
+    } else {
+        QDECREF(bs_entry->state.options);
+        QDECREF(bs_entry->state.explicit_options);
+    }
+
+    bs_entry->state.bs = bs;
+    bs_entry->state.options = options;
+    bs_entry->state.explicit_options = explicit_options;
+    bs_entry->state.flags = flags;
+
     QLIST_FOREACH(child, &bs->children, next) {
         QDict *new_child_options;
         char *child_key_dot;
@@ -2787,19 +2800,6 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
                                 child->role, options, flags);
     }
 
-    if (!bs_entry) {
-        bs_entry = g_new0(BlockReopenQueueEntry, 1);
-        QSIMPLEQ_INSERT_TAIL(bs_queue, bs_entry, entry);
-    } else {
-        QDECREF(bs_entry->state.options);
-        QDECREF(bs_entry->state.explicit_options);
-    }
-
-    bs_entry->state.bs = bs;
-    bs_entry->state.options = options;
-    bs_entry->state.explicit_options = explicit_options;
-    bs_entry->state.flags = flags;
-
     return bs_queue;
 }
 
-- 
2.13.5

On 09/15/2017 05:10 AM, Kevin Wolf wrote:
> We will calculate the required new permissions in the prepare stage of a
> reopen. Required permissions of children can be influenced by the
> changes made to their parents, but parents are independent from their
> children. This means that permissions need to be calculated top-down. In
> order to achieve this, queue parents before their children rather than
> queuing the children first.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org