[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for
From: |
Wen Congyang |
Subject: |
Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication |
Date: |
Wed, 14 Oct 2015 08:55:48 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 |
On 10/13/2015 06:12 PM, Fam Zheng wrote:
> On Tue, 10/13 17:46, Wen Congyang wrote:
>> On 10/13/2015 05:41 PM, Fam Zheng wrote:
>>> On Tue, 10/13 16:59, Wen Congyang wrote:
>>>> On 10/13/2015 12:25 AM, Stefan Hajnoczi wrote:
>>>>> On Fri, Sep 25, 2015 at 02:17:36PM +0800, Wen Congyang wrote:
>>>>>> +static void backup_job_completed(void *opaque, int ret)
>>>>>> +{
>>>>>> + BDRVReplicationState *s = opaque;
>>>>>> +
>>>>>> + if (s->replication_state != BLOCK_REPLICATION_DONE) {
>>>>>> + /* The backup job is cancelled unexpectedly */
>>>>>> + s->error = -EIO;
>>>>>> + }
>>>>>> +
>>>>>> + bdrv_op_block(s->hidden_disk, BLOCK_OP_TYPE_BACKUP_TARGET,
>>>>>> + s->active_disk->backing_blocker);
>>>>>> + bdrv_op_block(s->secondary_disk, BLOCK_OP_TYPE_BACKUP_SOURCE,
>>>>>> + s->hidden_disk->backing_blocker);
>>>>>> +
>>>>>> + bdrv_put_ref_bh_schedule(s->secondary_disk);
>>>>>
>>>>> Why is bdrv_put_ref_bh_schedule() necessary?
>>>>
>>>> It is copied from block_job_cb(). According to the comments in
>>>> bdrv_put_ref_bh_schedule():
>>>> /*
>>>> * Release a BDS reference in a BH
>>>> *
>>>> * It is not safe to use bdrv_unref() from a callback function when the
>>>> callers
>>>> * still need the BlockDriverState. In such cases we schedule a BH to
>>>> release
>>>> * the reference.
>>>> */
>>>>
>>>> If the comment is right, I think it is necessary to call
>>>> bdrv_put_ref_bh_schedule() here.
>>>> Because the job is created on the BDS s->secondary disk,
>>>> backup_job_completed() is
>>>> called in block_job_completed(), and we will still use s->secondary_disk
>>>> in block_job_release().
>>>
>>> Where is the matching bdrv_ref called?
>>
>> It is in block_job_create()....
>>
>> source: we call in bdrv_ref() in block_job_create(), and the user should
>> unref it.
>> target: the user call bdrv_ref(), and we will unref it in the job
>>
>> I don't know why we design it like this...
>>
>
> Maybe it's better to unref it in block_job_release. Then we can simply drop
> bdrv_put_ref_bh_schedule.
I agree with it.
Thanks
Wen Congyang
>
> Fam
> .
>
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Stefan Hajnoczi, 2015/10/12
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Wen Congyang, 2015/10/15
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Stefan Hajnoczi, 2015/10/15
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Wen Congyang, 2015/10/14
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Stefan Hajnoczi, 2015/10/15
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Wen Congyang, 2015/10/15
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Wen Congyang, 2015/10/16
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Stefan Hajnoczi, 2015/10/16
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Wen Congyang, 2015/10/26
- Re: [Qemu-devel] [Qemu-block] [PATCH v10 08/10] Implement new driver for block replication, Stefan Hajnoczi, 2015/10/27