Re: [PULL 06/18] qemu-img: Add --target-is-zero to convert

[David Edmondson]

On Thursday, 2020-02-20 at 10:36:04 -06, Eric Blake wrote:

> On 2/20/20 10:06 AM, Max Reitz wrote:
>> From: David Edmondson <address@hidden>
>> 
>> In many cases the target of a convert operation is a newly provisioned
>> target that the user knows is blank (reads as zero). In this situation
>> there is no requirement for qemu-img to wastefully zero out the entire
>> device.
>> 
>> Add a new option, --target-is-zero, allowing the user to indicate that
>> an existing target device will return zeros for all reads.
>> 
>> Signed-off-by: David Edmondson <address@hidden>
>> Message-Id: <address@hidden>
>> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>> Reviewed-by: Eric Blake <address@hidden>
>> Signed-off-by: Max Reitz <address@hidden>
>> ---
>>   docs/interop/qemu-img.rst |  9 ++++++++-
>>   qemu-img-cmds.hx          |  4 ++--
>>   qemu-img.c                | 26 +++++++++++++++++++++++---
>>   3 files changed, 33 insertions(+), 6 deletions(-)
>> 
>> diff --git a/docs/interop/qemu-img.rst b/docs/interop/qemu-img.rst
>> index 42e4451db4..5f40137c10 100644
>> --- a/docs/interop/qemu-img.rst
>> +++ b/docs/interop/qemu-img.rst
>> @@ -214,6 +214,13 @@ Parameters to convert subcommand:
>>     will still be printed.  Areas that cannot be read from the source will be
>>     treated as containing only zeroes.
>>   
>> +.. option:: --target-is-zero
>> +
>> +  Assume that reading the destination image will always return
>> +  zeros. This parameter is mutually exclusive with a destination image
>
> Late tweak now that this is in a pull request, so we may want a followup 
> patch, but:
>
> The image doesn't always return zeros after we write to it, maybe we 
> should tweak this sentence:
>
> Assume that reading the destination image will initially return all zeros.

I will send a patch for this.

> Also, my earlier comment about 'zeroes' one line before 'zeros' still 
> applies - although both spellings are valid, we look inconsistent when 
> we can't make up our mind within two adjacent paragraphs.

If we can agree on one of "zeros" or "zeroes" then I'm happy to send a
patch making it consistent everywhere.

I think that given there are existing functions with "zeroes" in the
name, I'd be inclined to go that way.

dme.
-- 
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