You can reproduce this by passing an invalid filter-node-name (like
"1234") to block-commit. In this case the base image is put in
read-write mode but is never reset back to read-only.

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/commit.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/block/commit.c b/block/commit.c
index ba60fef58a..698eda1dfe 100644
--- a/block/commit.c
+++ b/block/commit.c
@@ -384,6 +384,9 @@ fail:
     if (s->top) {
         blk_unref(s->top);
     }
+    if (s->base_read_only) {
+        bdrv_reopen_set_read_only(base, true, NULL);
+    }
     job_early_fail(&s->common.job);
     /* commit_top_bs has to be replaced after deleting the block job,
      * otherwise this would fail because of lack of permissions. */
-- 
2.11.0

On 11.04.19 14:32, Alberto Garcia wrote:
> You can reproduce this by passing an invalid filter-node-name (like
> "1234") to block-commit. In this case the base image is put in
> read-write mode but is never reset back to read-only.
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  block/commit.c | 3 +++
>  1 file changed, 3 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>