Hi all! As reported in https://bugzilla.redhat.com/show_bug.cgi?id=2004812 backup don't work when copy-before-write is not white-listed.
Yes, we do need copy-before-write filter for backup to work (like we always use copy-on-read filter in block-stream). The problem is that in bdrv_insert_node() (called to insert filters internally) we use bdrv_open(), which does a lot of things we don't need for internal node creation and among them check the white-list. Backup job should of course work when copy-before-write is not white-listed. As well, block-stream should work with not-white-listed copy-on-read. White-list is for user, not for internal implementation. Following Kevin's suggestion fix the problem by implementing a version of bdrv_new_open_driver() that supports QDict of options, and use it instead of bdrv_open(). Vladimir Sementsov-Ogievskiy (5): block: implement bdrv_new_open_driver_opts() block: bdrv_insert_node(): fix and improve error handling block: bdrv_insert_node(): doc and style block: bdrv_insert_node(): don't use bdrv_open() iotests/image-fleecing: declare requirement of copy-before-write include/block/block.h | 4 ++ block.c | 77 ++++++++++++++++++++----- tests/qemu-iotests/tests/image-fleecing | 1 + 3 files changed, 68 insertions(+), 14 deletions(-) -- 2.29.2
