Re: [Qemu-devel] [PATCH v2 12/16] block/mirror: Distinguish active from passive ops

[Max Reitz]

On 2018-02-27 10:12, Fam Zheng wrote:
> On Mon, 01/22 23:08, Max Reitz wrote:
>> Currently, the mirror block job only knows passive operations.  But once
>> we introduce active writes, we need to distinguish between the two; for
>> example, mirror_wait_for_free_in_flight_slot() should wait for a passive
>> operation because active writes will not use the same in-flight slots.
>>
>> Signed-off-by: Max Reitz <address@hidden>
>> ---
>>  block/mirror.c | 7 +++++--
>>  1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/block/mirror.c b/block/mirror.c
>> index 2363e79563..bb46f3c4e9 100644
>> --- a/block/mirror.c
>> +++ b/block/mirror.c
>> @@ -89,6 +89,7 @@ struct MirrorOp {
>>      int64_t *bytes_handled;
>>  
>>      bool is_pseudo_op;
>> +    bool is_active_write;
>>      CoQueue waiting_requests;
>>  
>>      QTAILQ_ENTRY(MirrorOp) next;
>> @@ -281,8 +282,10 @@ static inline void 
>> mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s)
>>           * some other operation to start, which may in fact be the
>>           * caller of this function.  Since there is only one pseudo op
>>           * at any given time, we will always find some real operation
>> -         * to wait on. */
>> -        if (!op->is_pseudo_op) {
>> +         * to wait on.
>> +         * Also, only non-active operations use up in-flight slots, so
>> +         * we can ignore active operations. */
>> +        if (!op->is_pseudo_op && !op->is_active_write) {
>>              qemu_co_queue_wait(&op->waiting_requests, NULL);
>>              return;
>>          }
>> -- 
>> 2.14.3
>>
> 
> I'd just squash this patch into 14 to avoid code churn.

I wanted to pull out as much as possible from 14 since it is massive as
it is, but if you think it makes reviewing even harder... Then I can put
it in there, of course.

Max

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