[PULL 33/34] block: Fix locking in qmp_block_resize()

[Kevin Wolf <kwolf@redhat.com>]

The drain functions assume that we hold the AioContext lock of the
drained block node. Make sure to actually take the lock.

Cc: qemu-stable@nongnu.org
Fixes: eb94b81a94bce112e6b206df846c1551aaf6cab6
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20201203172311.68232-3-kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 blockdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/blockdev.c b/blockdev.c
index 660c735c81..412354b4b6 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2481,13 +2481,16 @@ void coroutine_fn qmp_block_resize(bool has_device, const char *device,
         return;
     }
 
+    bdrv_co_lock(bs);
     bdrv_drained_begin(bs);
+    bdrv_co_unlock(bs);
+
     old_ctx = bdrv_co_enter(bs);
     blk_truncate(blk, size, false, PREALLOC_MODE_OFF, 0, errp);
     bdrv_co_leave(bs, old_ctx);
-    bdrv_drained_end(bs);
 
     bdrv_co_lock(bs);
+    bdrv_drained_end(bs);
     blk_unref(blk);
     bdrv_co_unlock(bs);
 }
-- 
2.29.2