Re: [Qemu-devel] [PATCH] block: Document BDRV_REQ_WRITE_UNCHANGED support

[Max Reitz <mreitz@redhat.com>]

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On 2018-05-02 16:03, Max Reitz wrote:
> Add BDRV_REQ_WRITE_UNCHANGED to the list of flags honored during pwrite
> and pwrite_zeroes, and also add a note on when you absolutely need to
> support it.
> 
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
> I did not include a note on how this might be useful to protocol
> drivers, because BDRV_REQ_WRITE_UNCHANGED requests will usually not end
> up on the protocol level anyway.
> (I suppose it would be possible in theory if a protocol driver reports a
>  certain range as unallocated and the user installs a copy-on-read
>  driver on top, but I think every protocol driver currently reports
>  everything as allocated.)
> ---
>  include/block/block_int.h | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)

Thanks for the review, applied to my block branch.

Max


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