Re: [Qemu-devel] [PATCH v2 3/5] qcow2: Employ metadata overlap checks

[Max Reitz <mreitz@redhat.com>]

Am 29.08.2013 11:18, schrieb Kevin Wolf:
> Am 28.08.2013 um 16:55 hat Max Reitz geschrieben:
>> The pre-write overlap check function is now called before most of the
>> qcow2 writes (aborting it on collision or other error).
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block/qcow2-cache.c    | 17 +++++++++++++++++
>>   block/qcow2-cluster.c  | 21 +++++++++++++++++++++
>>   block/qcow2-snapshot.c | 22 ++++++++++++++++++++++
>>   block/qcow2.c          | 36 +++++++++++++++++++++++++++++++++++-
>>   4 files changed, 95 insertions(+), 1 deletion(-)
>> @@ -1753,10 +1779,18 @@ static int qcow2_save_vmstate(BlockDriverState *bs, QEMUIOVector *qiov,
>>       BDRVQcowState *s = bs->opaque;
>>       int growable = bs->growable;
>>       int ret;
>> +    int64_t offset = qcow2_vm_state_offset(s) + pos;
>>   
>>       BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE);
>>       bs->growable = 1;
>> -    ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov);
>> +
>> +    ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, offset,
>> +                                        qiov->size);
>> +    if (ret < 0) {
>> +        return ret;
>> +    }
>> +
>> +    ret = bdrv_pwritev(bs, offset, qiov);
>>       bs->growable = growable;
>>   
>>       return ret;
> Sorry for not catching it in v1, this one is actually wrong. The
> bdrv_pwritev() is against bs, not bs->file, so you would be comparing
> virtual/guest offsets with physical/host offsets.
Oh, yes, sorry; thanks for noticing. I do this mistake way too often – I 
think it's time for some regex to catch it…

Max