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Re: [libvirt] [PATCH 5/9] storage: Break out actual raw cloning to separate function.



On Fri, Jul 10, 2009 at 04:47:02PM -0400, Cole Robinson wrote:
> The CreateRaw function has some 'file' only assumptions, so break the agnostic
> cloning bits to a separate function.
> ---
>  src/storage_backend.c |  160 ++++++++++++++++++++++++++++---------------------
>  1 files changed, 92 insertions(+), 68 deletions(-)


ACK. One thing occurs to me for the future. We should probably use
the fallocate() call to attempt to pre-allocate the  target volume
and then copy the data across afterwards. fallocate() will only
succeeed on filesystems supporting extents (eg ext4), so it is
guareteened always fast (unlike posix_fallocate() which  falls back
to writing zeros.  Anyway, by attempting fallocate() before cloning
we get good extents allocation for filesystems where this matters.


Daniel
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