From 6e9cc0518113da423252a1fea328f27dc7bcf997 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Tue, 18 Feb 2020 11:34:46 +0100 Subject: [PATCH] mirror: Double-check immediately before replacing There is no guarantee that we can still replace the node we want to replace at the end of the mirror job. Double-check by calling bdrv_recurse_can_replace(). Signed-off-by: Max Reitz Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <20200218103454.296704-12-mreitz@redhat.com> Signed-off-by: Kevin Wolf --- block/mirror.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/block/mirror.c b/block/mirror.c index cacbc70014..447051dbc6 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -700,7 +700,19 @@ static int mirror_exit_common(Job *job) * drain potential other users of the BDS before changing the graph. */ assert(s->in_drain); bdrv_drained_begin(target_bs); - bdrv_replace_node(to_replace, target_bs, &local_err); + /* + * Cannot use check_to_replace_node() here, because that would + * check for an op blocker on @to_replace, and we have our own + * there. + */ + if (bdrv_recurse_can_replace(src, to_replace)) { + bdrv_replace_node(to_replace, target_bs, &local_err); + } else { + error_setg(&local_err, "Can no longer replace '%s' by '%s', " + "because it can no longer be guaranteed that doing so " + "would not lead to an abrupt change of visible data", + to_replace->node_name, target_bs->node_name); + } bdrv_drained_end(target_bs); if (local_err) { error_report_err(local_err);