Re: [PATCH -next] mm: zswap: update comment for struct zswap_entry

[xiujianfeng <xiujianfeng@huawei.com>]

Hi Yosry,

On 2023/8/8 13:59, Yosry Ahmed wrote:
> Hi Xiu,
> 
> On Mon, Aug 7, 2023 at 7:49 PM Xiu Jianfeng <xiujianfeng@huaweicloud.com> wrote:
>>
>> From: Xiu Jianfeng <xiujianfeng@huawei.com>
>>
>> Since commit 0bb488498c98 ("mm: zswap: remove zswap_header"), the
>> 'offset' has been replaced by swpentry, update the comment for it,
>> and also add comment for 'objcg'.
>>
>> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
>> ---
>>  mm/zswap.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index 5b56d38e7339..d7863c139c82 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -182,7 +182,7 @@ struct zswap_pool {
>>   * page within zswap.
>>   *
>>   * rbnode - links the entry into red-black tree for the appropriate swap type
>> - * offset - the swap offset for the entry.  Index into the red-black tree.
>> + * swpentry - the swap entry for the entry, include 'type' and 'offset' fields
> 
> 
> This is not the place to document that a swap entry has 'type' and
> 'offset' fields.
> 
> I would also avoid the repetitive 'entry'. Maybe something like:
> swpentry - associated swap entry, the offset indexes into the red-black tree
> 
>>
>>   * refcount - the number of outstanding reference to the entry. This is needed
>>   *            to protect against premature freeing of the entry by code
>>   *            concurrent calls to load, invalidate, and writeback.  The lock
>> @@ -195,6 +195,7 @@ struct zswap_pool {
>>   * pool - the zswap_pool the entry's data is in
>>   * handle - zpool allocation handle that stores the compressed page data
>>   * value - value of the same-value filled pages which have same content
>> + * objcg - the obj_cgroup(actually memcg) this entry belongs to
> 
> 
> Again, not the place to document that objcg is an abstraction layer
> above a memcg.
> 
> I would do something like:
> objcg - the obj_cgroup that the compressed memory is charged to

Thanks for your review, I've just sent out the v2 patch.

> 
>>
>>   * lru - handle to the pool's lru used to evict pages.
>>   */
>>  struct zswap_entry {
>> --
>> 2.34.1
>>
>>