From c0829cb1fd5e0b35abfcf9fc3f04502c1ed5d7b6 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Mon, 24 Jan 2022 18:37:41 +0100 Subject: [PATCH] block: bdrv_set_backing_hd(): use drained section Graph modifications should be done in drained section. stream_prepare() handler of block stream job call bdrv_set_backing_hd() without using drained section and it's theoretically possible that some IO request will interleave with graph modification and will use outdated pointers to removed block nodes. Some other callers use bdrv_set_backing_hd() not caring about drained sections too. So it seems good to make a drained section exactly in bdrv_set_backing_hd(). Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20220124173741.2984056-1-vsementsov@virtuozzo.com> Signed-off-by: Kevin Wolf --- block.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block.c b/block.c index 7b3ce415d8..b54d59d1fa 100644 --- a/block.c +++ b/block.c @@ -3341,6 +3341,8 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, int ret; Transaction *tran = tran_new(); + bdrv_drained_begin(bs); + ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp); if (ret < 0) { goto out; @@ -3350,6 +3352,8 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, out: tran_finalize(tran, ret); + bdrv_drained_end(bs); + return ret; }