Re: [Qemu-devel] About the snapshot

[Stefan Hajnoczi]

On Tue, Dec 6, 2011 at 10:01 AM, Zhi Hui Li <address@hidden> wrote:
> On 2011年12月06日 17:40, Stefan Hajnoczi wrote:
>>
>> On Tue, Dec 6, 2011 at 9:07 AM, Zhi Hui Li<address@hidden>
>>  wrote:
>>>
>>>
>>> 1) :
>>>
>>> for example:
>>>
>>> BDRVQcowState *s = bs->opaque;
>>>
>>> s->snapshots
>>> s->nb_snapshots
>>>
>>>
>>> 1:use the command:   qemu-img snapshot ./test.qcow2  -c aa
>>> the memory of the s->snapshot don't free,
>>> if the s->nb_snapshots is large, Does it have some problems.
>>>
>>> 2: use the command:  qemu-system-x86_64  ./test.qcow2 -snapshot
>>> when the program ends, Does it need to free the s->snapshots ?
>>
>>
>> These two commands are unrelated.  QEMU uses the term "snapshot" for
>> several different features:
>>
>> 1. qemu-img snapshot refers to "internal snapshots" that are contained
>> within qcow2 image files.  The savevm/loadvm/delvm monitor commands
>> operate on internal snapshots.
>>
>> 2. qemu -snapshot refers to a temporary qcow2 image file created to
>> buffer any data that the guest writes.  When QEMU exits your disk
>> image is not modified and the temporary qcow2 file is deleted.  You
>> can also apply the buffer to the disk image using the "commit" monitor
>> command.
>
>
> yes, I understand what you say, but the qemu-img and savevm both call the
> function of qcow2_snapshot_create, when I use the command qemu-img snapshot
> ./test.qcow2  -c aa,
> but the memory of the s->snapshot don't free.

Okay, I think you're saying that in #1 s->snapshots is leaked because
qcow2_free_snapshots() is not being called from qcow2_close().

Do you want to send a patch to fix this?

Stefan