block: Keep subtree drained in drop_intermediate

bdrv_drop_intermediate() calls BdrvChildRole.update_filename().  That
may poll, thus changing the graph, which potentially breaks the
QLIST_FOREACH_SAFE() loop.

Just keep the whole subtree drained.  This is probably the right thing
to do anyway (dropping nodes while the subtree is not drained seems
wrong).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
stable-4.2
Max Reitz 2019-07-22 15:33:43 +02:00 committed by Kevin Wolf
parent e444fa8312
commit 637d54a5f3
1 changed files with 2 additions and 0 deletions

View File

@ -4491,6 +4491,7 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
int ret = -EIO;
bdrv_ref(top);
bdrv_subtree_drained_begin(top);
if (!top->drv || !base->drv) {
goto exit;
@ -4562,6 +4563,7 @@ int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
ret = 0;
exit:
bdrv_subtree_drained_end(top);
bdrv_unref(top);
return ret;
}