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From bc78ee07bf400cbff0021367e05d308870471710 Mon Sep 17 00:00:00 2001
From: Sergio Lopez Pascual <slp@redhat.com>
Date: Fri, 7 Feb 2020 11:27:45 +0000
Subject: [PATCH 12/18] backup-top: Begin drain earlier

RH-Author: Sergio Lopez Pascual <slp@redhat.com>
Message-id: <20200207112749.25073-6-slp@redhat.com>
Patchwork-id: 93757
O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 5/9] backup-top: Begin drain earlier
Bugzilla: 1745606 1746217 1773517 1779036 1782111 1782175 1783965
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Max Reitz <mreitz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

From: Max Reitz <mreitz@redhat.com>

When dropping backup-top, we need to drain the node before freeing the
BlockCopyState.  Otherwise, requests may still be in flight and then the
assertion in shres_destroy() will fail.

(This becomes visible in intermittent failure of 056.)

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191219182638.104621-1-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit 503ca1262bab2c11c533a4816d1ff4297d4f58a6)
Signed-off-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/backup-top.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/backup-top.c b/block/backup-top.c
index 7cdb1f8..818d3f2 100644
--- a/block/backup-top.c
+++ b/block/backup-top.c
@@ -257,12 +257,12 @@ void bdrv_backup_top_drop(BlockDriverState *bs)
     BDRVBackupTopState *s = bs->opaque;
     AioContext *aio_context = bdrv_get_aio_context(bs);
 
-    block_copy_state_free(s->bcs);
-
     aio_context_acquire(aio_context);
 
     bdrv_drained_begin(bs);
 
+    block_copy_state_free(s->bcs);
+
     s->active = false;
     bdrv_child_refresh_perms(bs, bs->backing, &error_abort);
     bdrv_replace_node(bs, backing_bs(bs), &error_abort);
-- 
1.8.3.1