From b8a78d2f99bb481e78686ef2e0beb369b5563d87 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 3 Sep 2019 15:28:28 +0200 Subject: [PATCH 23/23] block: Drain source node in bdrv_replace_node() RH-Author: Kevin Wolf Message-id: <20190903152828.15668-2-kwolf@redhat.com> Patchwork-id: 90257 O-Subject: [RHEL-7.7.z qemu-kvm PATCH 1/1] block: Drain source node in bdrv_replace_node() Bugzilla: 1711643 RH-Acked-by: John Snow RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Pankaj Gupta Instead of just asserting that no requests are in flight in bdrv_replace_node(), which is a requirement that most callers ignore, we can just drain the source node right there. This fixes at least starting a commit job while I/O is active on the backing chain, but probably other callers, too. Having requests in flight on the target node isn't a problem because the target just gets new parents, but the call path of running requests isn't modified. So we can just drop this assertion without a replacement. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1711643 Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz (cherry picked from commit f871abd60f4b67547e62c57c9bec19420052be39) Signed-off-by: Kevin Wolf Signed-off-by: Miroslav Rezanina --- block.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index 7061f9b..4986516 100644 --- a/block.c +++ b/block.c @@ -3505,13 +3505,13 @@ void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, uint64_t perm = 0, shared = BLK_PERM_ALL; int ret; - assert(!atomic_read(&from->in_flight)); - assert(!atomic_read(&to->in_flight)); - /* Make sure that @from doesn't go away until we have successfully attached * all of its parents to @to. */ bdrv_ref(from); + assert(qemu_get_current_aio_context() == qemu_get_aio_context()); + bdrv_drained_begin(from); + /* Put all parents into @list and calculate their cumulative permissions */ QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { if (!should_update_child(c, to)) { @@ -3546,6 +3546,7 @@ void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, out: g_slist_free(list); + bdrv_drained_end(from); bdrv_unref(from); } -- 1.8.3.1