qcow2_do_open() calls a few no_co_wrappers that wrap functions taking
the graph lock internally as a writer. Therefore, it can't hold the
reader lock across these calls, it causes deadlocks. Drop the lock
temporarily around the calls.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/qcow2.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/block/qcow2.c b/block/qcow2.c
index 73f36447f9..b00b4e7575 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1619,9 +1619,11 @@ qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
if (open_data_file) {
/* Open external data file */
+ bdrv_graph_co_rdunlock();
s->data_file = bdrv_co_open_child(NULL, options, "data-file", bs,
&child_of_bds, BDRV_CHILD_DATA,
true, errp);
+ bdrv_graph_co_rdlock();
if (*errp) {
ret = -EINVAL;
goto fail;
@@ -1629,10 +1631,12 @@ qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) {
if (!s->data_file && s->image_data_file) {
+ bdrv_graph_co_rdunlock();
s->data_file = bdrv_co_open_child(s->image_data_file, options,
"data-file", bs,
&child_of_bds,
BDRV_CHILD_DATA, false, errp);
+ bdrv_graph_co_rdlock();
if (!s->data_file) {
ret = -EINVAL;
goto fail;
@@ -1857,7 +1861,9 @@ qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
fail:
g_free(s->image_data_file);
if (open_data_file && has_data_file(bs)) {
+ bdrv_graph_co_rdunlock();
bdrv_unref_child(bs, s->data_file);
+ bdrv_graph_co_rdlock();
s->data_file = NULL;
}
g_free(s->unknown_header_fields);
--
2.40.1