Re: [PATCH 2/3] dm pcache: fix cache info indexing

[Dongsheng Yang <dongsheng.yang@linux.dev>]

在 12/5/2025 12:01 AM, Mikulas Patocka 写道:
>
> On Thu, 4 Dec 2025, Dongsheng Yang wrote:
>
>> From: Li Chen <chenl311@chinatelecom.cn>
>>
>> The on-media cache_info index used sizeof(struct) instead of the
>> 4K metadata stride, so gc_percent updates from dmsetup message
>> were written between slots and lost after reboot. Use
>> PCACHE_CACHE_INFO_SIZE in get_cache_info_addr() and align
>> info_index with the slot returned by pcache_meta_find_latest().
>>
>> Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
>> Signed-off-by: Dongsheng Yang <dongsheng.yang@linux.dev>
>> ---
>>   drivers/md/dm-pcache/cache.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/md/dm-pcache/cache.c b/drivers/md/dm-pcache/cache.c
>> index 9289c016b7c9..bcc4e509aa69 100644
>> --- a/drivers/md/dm-pcache/cache.c
>> +++ b/drivers/md/dm-pcache/cache.c
>> @@ -8,9 +8,11 @@
>>   
>>   struct kmem_cache *key_cache;
>>   
>> -static inline struct pcache_cache_info *get_cache_info_addr(struct pcache_cache *cache)
>> +static inline struct pcache_cache_info *
>> +get_cache_info_addr(struct pcache_cache *cache)
>>   {
>> -	return cache->cache_info_addr + cache->info_index;
>> +	return (struct pcache_cache_info *)((char *)cache->cache_info_addr +
>> +						(size_t)cache->info_index * PCACHE_CACHE_INFO_SIZE);
>>   }
>>   
>>   static void cache_info_write(struct pcache_cache *cache)
>> @@ -49,6 +51,8 @@ static int cache_info_init(struct pcache_cache *cache, struct pcache_cache_optio
>>   			return -EINVAL;
>>   		}
>>   
>> +		cache->info_index = ((char *)cache_info_addr - (char *)cache->cache_info_addr) / PCACHE_CACHE_INFO_SIZE;
>> +
>>   		return 0;
>>   	}
>>   
>> -- 
>> 2.43.0
> I already staged the patch below? Should I revert it and stage your new
> patch?


Yes, please revert it, I will send a v2 patchset, please pick the v2 patch.


Thanx

>
> Mikulas
>
>
> diff --git a/drivers/md/dm-pcache/cache.c b/drivers/md/dm-pcache/cache.c
> index d8e92367d947..9554d1158450 100644
> --- a/drivers/md/dm-pcache/cache.c
> +++ b/drivers/md/dm-pcache/cache.c
> @@ -8,9 +8,11 @@
>
>   struct kmem_cache *key_cache;
>
> -static inline struct pcache_cache_info *get_cache_info_addr(struct pcache_cache *cache)
> +static inline struct pcache_cache_info *
> +get_cache_info_addr(struct pcache_cache *cache)
>   {
> -       return cache->cache_info_addr + cache->info_index;
> +       return (struct pcache_cache_info *)((char *)cache->cache_info_addr
> +
> +                                               (size_t)cache->info_index * PCACHE_CACHE_INFO_SIZE);
>   }
>
>   static void cache_info_write(struct pcache_cache *cache)
> @@ -40,7 +42,12 @@ static int cache_info_init(struct pcache_cache *cache,
> struct pcache_cache_optio
>          if (IS_ERR(cache_info_addr))
>                  return PTR_ERR(cache_info_addr);
>
> -       if (cache_info_addr) {
> +    if (cache_info_addr) {
> +               int index = ((char *)cache_info_addr - (char *)cache->cache_info_addr) /
> +                               PCACHE_CACHE_INFO_SIZE;
> +
> +               cache->info_index = (index + 1) % PCACHE_META_INDEX_MAX;
> +
>                  if (opts->data_crc !=
>                                  (cache->cache_info.flags & PCACHE_CACHE_FLAGS_DATA_CRC)) {
>                          pcache_dev_err(pcache, "invalid option for data_crc: %s, expected: %s",
>