Consider that as RFC. I'm preparing an alternative and more efficient fleecing scheme, based on special block driver, not on backing link.
So, this will be rebased, and probably some permission-related difficulties may be avoided. 21.07.2021 17:04, Vladimir Sementsov-Ogievskiy wrote:
Hi all! Here is push-backup with fleecing. What is it: 1. Make fleecing scheme guest blk | |root v copy-before-write filter -------> temp qcow2 | | |file | backing V | active disk <------------------------- 2. Start backup job from temp qcow2 to final remote target (NBD or something) Benefit in comparison with simple backup job: for remote final target write operations are not very fast. And guest have to wait for copy-before-write operations. With fleecing scheme target for copy-before-write operations is local qcow2 file with faster access than actual backup target. So, guest is less disturbed by copy-before-write operations. Based-on: <20210721100555.45594-1-vsement...@virtuozzo.com> ([PATCH v6 00/33] block: publish backup-top filter) v2: 01: changed to simply check s->target->perm 06: make explicit immutable-source parameter instead of auto-detecting Vladimir Sementsov-Ogievskiy (6): block/block-copy: use write-unchanged for fleecing scheme block/copy-before-write: require BLK_PERM_WRITE_UNCHANGED for fleecing block: share writes on backing child of fleecing node block: blk_root(): return non-const pointer qapi: backup: add immutable-source paramter iotests/image-fleecing: test push backup with fleecing qapi/block-core.json | 12 ++- block/copy-before-write.h | 1 + include/block/block_int.h | 1 + include/sysemu/block-backend.h | 2 +- block.c | 3 +- block/backup.c | 71 ++++++++++++- block/block-backend.c | 2 +- block/block-copy.c | 18 +++- block/copy-before-write.c | 48 ++++++++- block/replication.c | 2 +- blockdev.c | 1 + tests/qemu-iotests/tests/image-fleecing | 105 +++++++++++++++----- tests/qemu-iotests/tests/image-fleecing.out | 61 ++++++++++++ 13 files changed, 287 insertions(+), 40 deletions(-)
-- Best regards, Vladimir