Hi Paolo,

Thanks. I found a function called bdrv_invalidate_cache() in qcow2.c. After
migration, it will be called to invalidate the cache of the block device?


On Fri, Jun 27, 2014 at 5:49 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:

> Il 27/06/2014 21:41, Xiongzi Ge ha scritto:
>
>
>> When I studied the code, I found in migration.c,
>> bdrv_clear_incoming_migration_all();
>>
>> the cache of the bdrv devices will be deleted.
>>
>> Is this the one for the functions to be called after migration?
>>
>> Does the bdrv device need to be reopen or load state in block.c?
>>
>> I would like to find this function to add my new code.
>>
>
> This function is not going to do anything if your code is in "raw" format.
>  In particular, it has *nothing* to do with the guest OS's cache.  That
> cache is managed by the guest OS and, as I have already told you multiple
> times, there is *nothing* that QEMU can do about it.
>
> All you can do is use O_DIRECT in the guest.
>
> Paolo
>