On 25.09.19 15:45, Vladimir Sementsov-Ogievskiy wrote:
> 20.09.2019 18:27, Max Reitz wrote:
>> We will need this to verify that Quorum can let one of its children be
>> replaced without breaking anything else.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   block/quorum.c | 23 +++++++++++++++++++++++
>>   1 file changed, 23 insertions(+)
>>
>> diff --git a/block/quorum.c b/block/quorum.c
>> index cf2171cc74..207054a64e 100644
>> --- a/block/quorum.c
>> +++ b/block/quorum.c
>> @@ -67,6 +67,13 @@ typedef struct QuorumVotes {
>>   
>>   typedef struct QuorumChild {
>>       BdrvChild *child;
>> +
>> +    /*
>> +     * If set, check whether this node can be replaced without any
>> +     * other parent noticing: Unshare CONSISTENT_READ, and take the
>> +     * WRITE permission.
>> +     */
>> +    bool to_be_replaced;
>>   } QuorumChild;
>>   
>>   /* the following structure holds the state of one quorum instance */
>> @@ -1128,6 +1135,16 @@ static void quorum_child_perm(BlockDriverState *bs, BdrvChild *c,
>>                                 uint64_t perm, uint64_t shared,
>>                                 uint64_t *nperm, uint64_t *nshared)
>>   {
>> +    BDRVQuorumState *s = bs->opaque;
>> +    int i;
>> +
>> +    for (i = 0; i < s->num_children; i++) {
>> +        if (s->children[i].child == c) {
>> +            break;
>> +        }
>> +    }
>> +    assert(!c || i < s->num_children);
> 
> seems, the loop is useless if c == NULL.

Not wrong.  I’ll put it all into an if (c) and initialize i to -1.

Max