Re: [f2fs-dev] [PATCH v3 01/12] f2fs: cache: implement metadata cache

[Chao Yu <chao@kernel.org>]

On 8/28/26 00:56, Daeho Jeong wrote:
> The idea is to drop list_lock completely from f2fs_find_cache() by
> deferring LRU rotation to the shrinker (like page cache's
> PG_referenced / clock algorithm):

Ah, I see, let me implement the logic as you suggested, thanks for the idea!

> 
> In f2fs_find_cache() (no list_lock at all):
> 
> if (entry) {
>     f2fs_cache_get(entry);
>     set_bit(F2FS_BLOCK_REFERENCED, &entry->state);
> }
> 
> In f2fs_do_shrink_cache() Phase 1 (under list_lock):
> 
> list_for_each_entry_safe(entry, next, &cache->lru_list, list) {
>     /* If accessed, give it a second chance and rotate to tail */
>     if (test_and_clear_bit(F2FS_BLOCK_REFERENCED, &entry->state)) {
>         list_move_tail(&entry->list, &cache->lru_list);
>         continue;
>     }
>     ...
>     /* Reclaim cold entry */
> }
> 
> This completely eliminates list_lock overhead from the read lookup
> path while keeping active entries protected from eviction.
Thanks,