Re: [Qemu-devel] [PATCH 1/5] RFC: Efficient VM backup for qemu (v1)

[Dietmar Maurer]

> In short, the idea is that you can stick filters on top of a 
> BlockDriverState, so
> that any read/writes (and possibly more requests, if necessary) are routed
> through the filter before they are passed to the block driver of this BDS.
> Filters would be implemented as BlockDrivers, i.e. you could implement
> .bdrv_co_write() in a filter to intercept all writes to an image.

I am quite unsure if that make things easier.