[PATCH v2 06/15] block: Fix locking for bdrv_reopen_queue_child()

[Kevin Wolf <kwolf@redhat.com>]

Callers don't agree whether bdrv_reopen_queue_child() should be called
with the AioContext lock held or not. Standardise on holding the lock
(as done by QMP blockdev-reopen and the replication block driver) and
fix bdrv_reopen() to do the same.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index 214e5055a5..191dfc5d0c 100644
--- a/block.c
+++ b/block.c
@@ -4153,6 +4153,8 @@ static bool bdrv_recurse_has_child(BlockDriverState *bs,
  * bs_queue, or the existing bs_queue being used.
  *
  * bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple().
+ *
+ * To be called with bs->aio_context locked.
  */
 static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
                                                  BlockDriverState *bs,
@@ -4311,6 +4313,7 @@ static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
     return bs_queue;
 }
 
+/* To be called with bs->aio_context locked */
 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
                                     BlockDriverState *bs,
                                     QDict *options, bool keep_old_opts)
@@ -4475,11 +4478,11 @@ int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts,
     GLOBAL_STATE_CODE();
 
     bdrv_subtree_drained_begin(bs);
+    queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
+
     if (ctx != qemu_get_aio_context()) {
         aio_context_release(ctx);
     }
-
-    queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts);
     ret = bdrv_reopen_multiple(queue, errp);
 
     if (ctx != qemu_get_aio_context()) {
-- 
2.38.1