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Re: [Qemu-block] [PATCH] block: Document BDRV_REQ_WRITE_UNCHANGED suppor
From: |
Max Reitz |
Subject: |
Re: [Qemu-block] [PATCH] block: Document BDRV_REQ_WRITE_UNCHANGED support |
Date: |
Wed, 9 May 2018 22:10:18 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
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 <address@hidden>
> ---
> 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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