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Date: Thu, 26 Feb 2015 15:08:03 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [RFC PATCH 07/14] NBD client: implement block
 driver interfaces for block replication
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To: Max Reitz <mreitz@redhat.com>, Wen Congyang <wency@cn.fujitsu.com>, qemu devel <qemu-devel@nongnu.org>, Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>, Jiang Yunhong <yunhong.jiang@intel.com>, Dong Eddie <eddie.dong@intel.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Gonglei <arei.gonglei@huawei.com>, Yang Hongyang <yanghy@cn.fujitsu.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>



On 23/02/2015 22:41, Max Reitz wrote:
>>
>>   }
>>   +static int nbd_start_replication(BlockDriverState *bs, int mode)
>> +{
>> +    BDRVNBDState *s = bs->opaque;
>> +    Error *local_err = NULL;
>> +    int ret;
>> +
>> +    /*
>> +     * TODO: support COLO_SECONDARY_MODE if we allow secondary
>> +     * QEMU becoming primary QEMU.
>> +     */
>> +    if (mode != COLO_PRIMARY_MODE) {
>> +        return -1;
> 
> Once again, I'd like -ENOTSUP more (or -EINVAL or whatever you prefer).

Using the Error API is the right thing to do here.

Paolo