Re: [Qemu-block] [PATCH v5 4/4] block/backup: fix fleecing scheme: use serialized writes

2018-07-09 Thread Fam Zheng
On Mon, 07/09 19:37, Vladimir Sementsov-Ogievskiy wrote: > Fleecing scheme works as follows: we want a kind of temporary snapshot > of active drive A. We create temporary image B, with B->backing = A. > Then we start backup(sync=none) from A to B. From this point, B reads > as point-in-time snapsho

[Qemu-block] [PATCH v5 4/4] block/backup: fix fleecing scheme: use serialized writes

2018-07-09 Thread Vladimir Sementsov-Ogievskiy
Fleecing scheme works as follows: we want a kind of temporary snapshot of active drive A. We create temporary image B, with B->backing = A. Then we start backup(sync=none) from A to B. From this point, B reads as point-in-time snapshot of A (A continues to be active drive, accepting guest IO). Thi