Re: [Qemu-block] [PATCH v9 8/9] qcow2: skip writing zero buffers to empty COW areas

[Alberto Garcia]

On Tue 08 May 2018 04:58:15 PM CEST, Anton Nefedov wrote:
> If COW areas of the newly allocated clusters are zeroes on the backing image,
> efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole
> cluster instead of writing explicit zero buffers later in perform_cow().
>
> iotest 060:
> write to the discarded cluster does not trigger COW anymore.
> Use a backing image instead.
>
> Signed-off-by: Anton Nefedov <address@hidden>

Reviewed-by: Alberto Garcia <address@hidden>

Berto