Re: [Qemu-devel] [PATCH v13 03/14] qcow2: Optimize bdrv_make_empty()

[Eric Blake <eblake@redhat.com>]

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On 10/22/2014 06:51 AM, Max Reitz wrote:
> bdrv_make_empty() is currently only called if the current image
> represents an external snapshot that has been committed to its base
> image; it is therefore unlikely to have internal snapshots. In this
> case, bdrv_make_empty() can be greatly sped up by emptying the L1 and
> refcount table (while having the dirty flag set, which only works for
> compat=1.1) and creating a trivial refcount structure.
> 
> If there are snapshots or for compat=0.10, fall back to the simple
> implementation (discard all clusters).
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  block/blkdebug.c      |   2 +
>  block/qcow2.c         | 143 ++++++++++++++++++++++++++++++++++++++++++++------
>  include/block/block.h |   2 +
>  3 files changed, 132 insertions(+), 15 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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