File block-Fix-locking-in-qmp_block_resize.patch of Package qemu.35260

From: Kevin Wolf <kwolf@redhat.com>
Date: Thu, 3 Dec 2020 18:23:10 +0100
Subject: block: Fix locking in qmp_block_resize()

Git-commit: 8089eab2bd5fb160b038e64e14cf7ffb3f37091e

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>
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 blockdev.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/blockdev.c b/blockdev.c
index a7f0149d64152651be78f6cd8e61..e4dfa65aa444346c3c09dbc6d1c5 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);
 }