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由 Anton Nefedov 提交于
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: NAnton Nefedov <anton.nefedov@virtuozzo.com> Message-id: 20190516142749.81019-2-anton.nefedov@virtuozzo.com Reviewed-by: NVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: NAlberto Garcia <berto@igalia.com> Signed-off-by: NMax Reitz <mreitz@redhat.com>
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