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Re: [Qemu-block] [PATCH v14 1/1] qcow2: skip writing zero buffers to emp
Re: [Qemu-block] [PATCH v14 1/1] qcow2: skip writing zero buffers to empty COW areas
Thu, 16 May 2019 14:51:31 +0000
16.05.2019 17:27, Anton Nefedov wrote:
> If COW areas of the newly allocated clusters are zeroes on the backing
> image, efficient bdrv_write_zeroes(flags=BDRV_REQ_NO_FALLBACK) 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: Vladimir Sementsov-Ogievskiy <address@hidden>