Am 28.02.24 um 15:15 schrieb Vladimir Sementsov-Ogievskiy: > Add a parameter that enables discard-after-copy. That is mostly useful > in "push backup with fleecing" scheme, when source is snapshot-access > format driver node, based on copy-before-write filter snapshot-access > API: > > [guest] [snapshot-access] ~~ blockdev-backup ~~> [backup target] > | | > | root | file > v v > [copy-before-write] > | | > | file | target > v v > [active disk] [temp.img] > > In this case discard-after-copy does two things: > > - discard data in temp.img to save disk space > - avoid further copy-before-write operation in discarded area > > Note that we have to declare WRITE permission on source in > copy-before-write filter, for discard to work. Still we can't take it > unconditionally, as it will break normal backup from RO source. So, we > have to add a parameter and pass it thorough bdrv_open flags. > > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@yandex-team.ru>
Reviewed-by: Fiona Ebner <f.eb...@proxmox.com>
