[Devel] [RFC PATCH vz9 v6 07/62] dm-ploop: convert wait_list and wb_batch_llist to use lockless lists

[Alexander Atanasov]

On 9.01.25 7:00, Pavel Tikhomirov wrote:
> 
> 
> On 12/6/24 05:55, Alexander Atanasov wrote:
>> diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
>> index a0fe92a592a1..fb49dc7bd7b0 100644
>> --- a/drivers/md/dm-ploop-map.c
>> +++ b/drivers/md/dm-ploop-map.c
>> @@ -382,13 +382,14 @@ static bool ploop_delay_if_md_busy(struct ploop 
>> *ploop, struct md_page *md,
>>       WARN_ON_ONCE(!list_empty(&pio->list));
>> -    write_lock_irqsave(&ploop->bat_rwlock, flags);
>> +    /* lock protects piwb */
>> +    read_lock_irqsave(&ploop->bat_rwlock, flags);
>>       piwb = md->piwb;
>>       if (piwb && (piwb->type != type || test_bit(MD_WRITEBACK, 
>> &md->status))) {
>> -        list_add_tail(&pio->list, &md->wait_list);
>> +        llist_add((struct llist_node *)(&pio->list), &md->wait_llist);
> 
> Probably we can have:
> 
> struct pio {
>    union {
>      struct list_head list;
>      struct llist_node llist;
>    };
> }
> 
> And use llist member where we need lock-less lists and use list where we 
> want doubly linked list.


tried that - did not work.
compiler errors from list macros, they do type checking - there is a 
third struct too - struct llist_head.


-- 
Regards,
Alexander Atanasov