[libvirt] [PULL 10/19] block: reverse order for reopen commits

From: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com&gt; 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 <vsementsov(a)virtuozzo.com&gt; Acked-by: Max Reitz <mreitz(a)redhat.com&gt; Acked-by: John Snow <jsnow(a)redhat.com&gt; Message-id: 20190927122355.7344-3-vsementsov(a)virtuozzo.com Signed-off-by: John Snow <jsnow(a)redhat.com&gt; --- block.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/block.c b/block.c index aaf5d796284..c548885608d 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); } -- 2.21.0