04.11.2021 13:38, Hanna Reitz wrote:
bdrv_cor_filter_drop() modifies the block graph. That means that other
parties can also modify the block graph before it returns. Therefore,
we cannot assume that the result of a graph traversal we did before
remains valid afterwards.
We should thus fetch `base` and `unfiltered_base` afterwards instead of
before.
Signed-off-by: Hanna Reitz <hre...@redhat.com>
The fact that other parties can modify graph during our graph modification is a
global problem.. The patch doesn't fix it, but reduces its effect in specific
case.. OK.
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
block/stream.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/block/stream.c b/block/stream.c
index 97bee482dc..e45113aed6 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -54,8 +54,8 @@ static int stream_prepare(Job *job)
{
StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
BlockDriverState *unfiltered_bs = bdrv_skip_filters(s->target_bs);
- BlockDriverState *base = bdrv_filter_or_cow_bs(s->above_base);
- BlockDriverState *unfiltered_base = bdrv_skip_filters(base);
+ BlockDriverState *base;
+ BlockDriverState *unfiltered_base;
Error *local_err = NULL;
int ret = 0;
@@ -63,6 +63,9 @@ static int stream_prepare(Job *job)
bdrv_cor_filter_drop(s->cor_filter_bs);
s->cor_filter_bs = NULL;
+ base = bdrv_filter_or_cow_bs(s->above_base);
+ unfiltered_base = bdrv_skip_filters(base);
+
if (bdrv_cow_child(unfiltered_bs)) {
const char *base_id = NULL, *base_fmt = NULL;
if (unfiltered_base) {
--
Best regards,
Vladimir
