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Re: [Qemu-devel] [PATCH v2 1/9] nbd: Allow unmap and fua during write ze
Re: [Qemu-devel] [PATCH v2 1/9] nbd: Allow unmap and fua during write zeroes
Fri, 18 Nov 2016 15:12:09 +0100
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On 17/11/2016 22:10, Max Reitz wrote:
> On 17.11.2016 21:13, Eric Blake wrote:
>> Commit fa778fff wired up support to send the NBD_CMD_WRITE_ZEROES,
>> but forgot to inform the block layer that FUA unmapping of zeroes is
>> supported. Without BDRV_REQ_MAY_UNMAP listed as a supported flag,
>> the block layer will always insist on the NBD layer passing
>> NBD_CMD_FLAG_NO_HOLE, resulting in the server always allocating
>> things even when it was desired to let the server punch holes.
>> Similarly, failing to set BDRV_REQ_FUA means that the client may
>> send unnecessary NBD_CMD_FLUSH when it could have instead used the
>> NBD_CMD_FLAG_FUA bit.
>> CC: address@hidden
>> Signed-off-by: Eric Blake <address@hidden>
>> block/nbd-client.c | 4 ++++
>> 1 file changed, 4 insertions(+)
> Reviewed-by: Max Reitz <address@hidden>
I'll take this one.
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