From e3e31dc87208007784b93a19f8efcdda90ea64f6 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Wed, 10 May 2023 22:35:56 +0200 Subject: [PATCH] qcow2: Unlock the graph in qcow2_do_open() where necessary 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 Message-Id: <20230510203601.418015-4-kwolf@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- 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);