Re: [Qemu-devel] [PATCH v2 5/9] qcow2: Rework qcow2_snapshot_create error handling

[Kevin Wolf <kwolf@redhat.com>]

Am 21.11.2011 17:47, schrieb Stefan Hajnoczi:
> On Fri, Nov 18, 2011 at 6:29 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> +    /*
>> +     * Increase the refcounts of all clusters and make sure everything is
>> +     * stable on disk before updating the snapshot table to contain a pointer
>> +     * to the new L1 table.
>> +     */
>> +    ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
>> +    if (ret < 0) {
>> +        goto fail;
>> +    }
>> +
>> +    ret = bdrv_flush(bs->file);
> 
> Do we need to explicitly flush the qcow2 cache to ensure metadata
> reaches the disk?

Yes, I think this should be a bdrv_flush(bs). I'm not completely sure if
it is really required, but I couldn't immediately tell why it's safe and
this isn't a fast path anyway, so I'll replace this before merging the
series (won't send out a v3 for this).

Kevin