Re: [PATCH 0/4] block: Do not call BlockDriver.bdrv_make_empty() directly

[Eric Blake <eblake@redhat.com>]

On 4/28/20 8:49 AM, Eric Blake wrote:
> On 4/28/20 8:26 AM, Max Reitz wrote:
>> Branch: https://github.com/XanClic/qemu.git fix-bdrv_make_empty-v1
>> Branch: https://git.xanclic.moe/XanClic/qemu.git fix-bdrv_make_empty-v1
>>
>> Hi,
>>
>> Right now, there is no centralized bdrv_make_empty() function.  Not only
>> is it bad style to call BlockDriver methods directly, it is also wrong,
>> unless the caller has a BdrvChild with BLK_PERM_WRITE taken.
> 
> I'm also in the middle of writing a patch series that adds a 
> corresponding .bdrv_make_empty driver callback.  I'll rebase that work 
> on top of this, as part of my efforts at fixing more code to rely on 
> bdrv_make_empty rather than directly querying 
> bdrv_has_zero_init[_truncate].

Correction - I'm working on adding .bdrv_make_zero, not .bdrv_make empty 
(which already exists), although maybe it really only needs to be one 
callback instead of two if we have decent flags.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
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