Re: [Qemu-devel] [PATCH v2 1/9] nbd: Allow unmap and fua during write zeroes

[Eric Blake]

On 11/17/2016 03:10 PM, 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

I guess this one is technically not for qemu-stable (as fa778fff is not
part of 2.7); rather, I just got carried away with the CC lines
distinguishing the first half of my series for 2.8 vs. the second for 2.9.

>> Signed-off-by: Eric Blake <address@hidden>
>> ---
>>  block/nbd-client.c | 4 ++++
>>  1 file changed, 4 insertions(+)
> 
> Reviewed-by: Max Reitz <address@hidden>
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

signature.asc
Description: OpenPGP digital signature