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