From: Vladimir Sementsov-Ogievskiy <vsementsov@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Acked-by: Max Reitz <mreitz@xxxxxxxxxx>
Acked-by: John Snow <jsnow@xxxxxxxxxx>
Message-id: 20190927122355.7344-3-vsementsov@xxxxxxxxxxxxx
Signed-off-by: John Snow <jsnow@xxxxxxxxxx>
---
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);
}
--
2.21.0
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