[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-block] [PATCH 1/1] nbd: implement bdrv_get_info callback

From: Eric Blake
Subject: Re: [Qemu-block] [PATCH 1/1] nbd: implement bdrv_get_info callback
Date: Fri, 26 Jan 2018 08:28:21 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2

On 01/26/2018 06:39 AM, Edgar Kaziakhmedov wrote:
> PIng
> So, let me know if I need to make any changes in patch
> On 1/18/18 1:09 PM, Paolo Bonzini wrote:
>> On 18/01/2018 12:51, Edgar Kaziakhmedov wrote:
>>> +static int nbd_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
>>> +{
>>> +    if (bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP) {
>>> +        bdi->can_write_zeroes_with_unmap = true;
>>> +    }
>>> +    return 0;
>>> +}
>>> +
>> Other drivers set the flag always, while NBD only sets it if the server
>> knows the flag.

Well, other drivers may be able to always implement it (NBD can only
implement it if the server supports WRITE_ZEROES - and I'm even in the
middle of working up an nbdkit patch [1] that makes it easier to write
an NBD server that specifically does not support WRITE_ZEROES to make
code paths like this easier to test)


>> I think NBD is more correct, so:
>> Reviewed-by: Paolo Bonzini <address@hidden>

Agreed; I'm fine queueing this on my NBD queue, except I'd first like to
hear Kevin's opinion:

>> However, it would be nice to remove can_write_zeroes_with_unmap from
>> BlockDriverInfo, and make bdrv_can_write_zeroes_with_unmap just return
>> !!(bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP).  Kevin, what do you
>> think?

Actually, I may even just give a shot at writing this alternative patch,
to make Kevin's decision easier.

Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Attachment: signature.asc
Description: OpenPGP digital signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]