[Libguestfs] [PATCH libnbd v3 2/3] copy: Use preferred block size for copying

[Richard W.M. Jones]

On Thu, Jun 30, 2022 at 05:38:14PM +0200, Laszlo Ersek wrote:
> > +static bool
> > +only_zeroes (const extent_list exts, size_t *i,
[...]
> > +
> > +    if (start >= offset + len)
> > +      break;
> > +
> 
> (13) I think we can insert a micro-optimization here:
> 
>     *i = j;
[...]
> The loop at the start of the function is correct, but here we can save
> some work for its next execution (in the next invocation of this function).

Just a note that I didn't do this optimization.

The reason is that it breaks the ability (which we don't use) of
calling only_zeroes twice on the same offset.  I just feel that it
might cause unexpected results if someone hoisted out the only_zeroes
call into a debug printf or similar.

I made the rest of the suggested changes, except for splitting out the
test into another commit - we surely want to keep the test with the
change that is being tested.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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