From 7094f12f868fc1b75b105bcc676e15964dab77af Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 11 Apr 2012 11:06:37 +0200
Subject: [PATCH] block: Drain requests in bdrv_close

If an AIO request is in flight that refers to a BlockDriverState that
has been closed and possibly even freed, more or less anything could
happen. I have seen segfaults, -EBADF return values and qcow2 sometimes
actually catches the situation in bdrv_close() and abort()s.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block.c b/block.c
index c0c90f061b..4b96654e7d 100644
--- a/block.c
+++ b/block.c
@@ -816,6 +816,8 @@ void bdrv_close(BlockDriverState *bs)
         if (bs->job) {
             block_job_cancel_sync(bs->job);
         }
+        bdrv_drain_all();
+
         if (bs == bs_snapshots) {
             bs_snapshots = NULL;
         }