commit 8aa045421979e59fa27cae6056471d33406a1eba
author Kevin Wolf <kwolf@redhat.com> Mon Jun 05 10:57:08 2023 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed Jun 28 08:46:18 2023 +0200
tree e8a9d9e37dbcd59b6af71804e3a8132d9a1ff61b
parent f665f01f729680077fc0ff2e5489618d9ecc380e

block: Fix AioContext locking in bdrv_open_backing_file()

bdrv_set_backing() requires the caller to hold the AioContext lock for
@backing_hd. Take it in bdrv_open_backing_file() before calling the
function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230605085711.21261-9-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

diff --git a/block.c b/block.c
index 9815a6b..dc691b9 100644
--- a/block.c
+++ b/block.c
@@ -3526,6 +3526,7 @@
     int ret = 0;
     bool implicit_backing = false;
     BlockDriverState *backing_hd;
+    AioContext *backing_hd_ctx;
     QDict *options;
     QDict *tmp_parent_options = NULL;
     Error *local_err = NULL;
@@ -3610,8 +3611,12 @@
 
     /* Hook up the backing file link; drop our reference, bs owns the
      * backing_hd reference now */
+    backing_hd_ctx = bdrv_get_aio_context(backing_hd);
+    aio_context_acquire(backing_hd_ctx);
     ret = bdrv_set_backing_hd(bs, backing_hd, errp);
     bdrv_unref(backing_hd);
+    aio_context_release(backing_hd_ctx);
+
     if (ret < 0) {
         goto free_exit;
     }