From fcd6a4f42deef7e9f28c7b82f7d340200fb7846e Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 27 Sep 2019 15:23:48 +0300 Subject: [PATCH] block: reverse order for reopen commits It's needed to fix reopening qcow2 with bitmaps to RW. Currently it can't work, as qcow2 needs write access to file child, to mark bitmaps in-image with IN_USE flag. But usually children goes after parents in reopen queue and file child is still RO on qcow2 reopen commit. Reverse reopen order to fix it. Signed-off-by: Vladimir Sementsov-Ogievskiy Acked-by: Max Reitz Acked-by: John Snow Message-id: 20190927122355.7344-3-vsementsov@virtuozzo.com Signed-off-by: John Snow --- block.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index 0347632c6c..cf312258a9 100644 --- a/block.c +++ b/block.c @@ -3486,10 +3486,16 @@ int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) bs_entry->perms_checked = true; } - /* If we reach this point, we have success and just need to apply the - * changes + /* + * If we reach this point, we have success and just need to apply the + * changes. + * + * Reverse order is used to comfort qcow2 driver: on commit it need to write + * IN_USE flag to the image, to mark bitmaps in the image as invalid. But + * children are usually goes after parents in reopen-queue, so go from last + * to first element. */ - QTAILQ_FOREACH(bs_entry, bs_queue, entry) { + QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { bdrv_reopen_commit(&bs_entry->state); } -- 2.39.2