From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CAA441FB1 for ; Thu, 27 Aug 2026 01:19:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787793564; cv=none; b=Z2wFoLo4Lr3b9QDYzbhKSB9IshtCj1rmFZkik2hMJxQD3tzSwdBEVVuLQlwtckLVZBWI1s+IuAlBUaEF4eNBPg9pLmZrDc83UC/THXIuDlRyZkVrkNCwBIHf3XJ9JtFR8ccmROIEEszXo3UNpY4TlRF2++4JKHraYwB5FEmGRz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787793564; c=relaxed/simple; bh=y/ZiTDzXr5A0pUSZzwOkw9mDpSERL3yT+EYir6nL4Bc=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=usuObbzrPnrJd2qYarSyowKIKTu99Y6RdefIDeUPHjsadx17R1u5roY8m8EM5r353i1mvxJ8iXrRtj1VGKnlS4MUuf2E/H5Cf3tznC2ZfWrjZhnMAZLqnqZQmot/E5pchbZ6a6+93duDNkYhwuUOYNdelfYWMFjx249u/KkXP+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bUgA6wmr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bUgA6wmr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 894F41F000E9; Thu, 27 Aug 2026 01:19:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787793562; bh=7a5U70eVfMS1stmxf9KVAvYn+g33/0c/WUy7xdXAJ10=; h=Date:Cc:Subject:To:References:From:In-Reply-To; b=bUgA6wmrXF6Zp7Oq0H7R3EALOuJAJJUmI/GCF0bupQMtG/a+4cQAxZfsCjlsAzIdc JWwWSejhQRVBdjWXQpVR2l2ShjOgkHxR2Qz3M4ocvN1cJMCfYKsqHGwazvZg4Noazc uVyJxYpJM2+4iVh3YM3ITmArZUDYBwzM5eNST7xeWo5a5bNWNVT4XDYdnRL9SQvQOV ICedMvlRftCi7izYNRBTo0AtEU6vXjkG75HPdZCvzCJrcSEpjHysc8cNJXlUxnoECU eXxgazeCvSUfO1Vt37pkxS4rphJ4Ij/0F1L60fjLkbbO49r+lyosuE9NS0DTvOQUN3 OsSsWoPcLr8oQ== Message-ID: <4880a9a6-4036-4fec-8507-552f1bfc9fbb@kernel.org> Date: Thu, 27 Aug 2026 09:19:19 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, jaegeuk@kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [f2fs-dev] [PATCH v3 03/12] f2fs: cache: introduce shrinker To: Daeho Jeong References: <20260825130126.2078627-1-chao@kernel.org> <20260825130126.2078627-4-chao@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 8/27/26 03:19, Daeho Jeong wrote: > On Tue, Aug 25, 2026 at 6:03 AM Chao Yu via Linux-f2fs-devel > wrote: >> >> This patch integrates the metadata cache into the F2FS memory shrinker >> subsystem to reclaim clean, unreferenced cached blocks under memory >> pressure. >> >> It implements f2fs_shrink_cache() using a 3-phase cache reclamin method: >> 1. isolate clean entries from lru list >> 2. truncate from radix tree under lock >> 3. splice un-reclaimed entries back >> >> And hooks the new interface into f2fs_shrink_count() and f2fs_shrink_scan(). >> >> Signed-off-by: Chao Yu >> --- >> fs/f2fs/cache.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++ >> fs/f2fs/cache.h | 3 ++ >> fs/f2fs/shrinker.c | 12 +++++++ >> 3 files changed, 96 insertions(+) >> >> diff --git a/fs/f2fs/cache.c b/fs/f2fs/cache.c >> index 8f09492c402f..3cee33c69880 100644 >> --- a/fs/f2fs/cache.c >> +++ b/fs/f2fs/cache.c >> @@ -534,3 +534,84 @@ void f2fs_destroy_cache(struct f2fs_cached_block_list *cache) >> f2fs_put_cache(entry, true); >> goto next; >> } >> + >> +static unsigned long f2fs_do_shrink_cache(struct f2fs_cached_block_list *cache, >> + unsigned long nr_to_scan) >> +{ >> + struct f2fs_cached_block *entry, *next; >> + LIST_HEAD(dispose_list); >> + LIST_HEAD(keep_list); >> + unsigned long freed = 0; >> + unsigned long isolated = 0; >> + >> + /* Phase 1: Isolate candidate entries from LRU list into dispose_list */ >> + spin_lock(&cache->list_lock); >> + list_for_each_entry_safe(entry, next, &cache->lru_list, list) { >> + if (isolated++ >= nr_to_scan) > > scanned? Okay, will clean. > >> + break; >> + >> + if (f2fs_cache_test_dirty(entry) || >> + f2fs_cache_test_writeback(entry) || >> + f2fs_cache_test_locked(entry)) >> + continue; >> + >> + if (f2fs_cache_refcount(entry) != 1) >> + continue; >> + >> + list_move_tail(&entry->list, &dispose_list); >> + } >> + spin_unlock(&cache->list_lock); >> + >> + /* Phase 2: Process isolated candidates one by one */ >> + while (1) { >> + spin_lock(&cache->list_lock); > > Why do we need this lock to protect local lists? I think we need to protect the entry from being relocated in f2fs_find_cache()? Thanks, > > Thanks, > >> + entry = list_first_entry_or_null(&dispose_list, >> + struct f2fs_cached_block, list); >> + if (!entry) { >> + spin_unlock(&cache->list_lock); >> + break; >> + } >> + f2fs_cache_get(entry); >> + list_move_tail(&entry->list, &keep_list); >> + spin_unlock(&cache->list_lock); >> + >> + if (!f2fs_trylock_cache(entry)) { >> + f2fs_put_cache(entry, false); >> + continue; >> + } >> + >> + /* the entry has been truncated */ >> + if (!entry->cache) { >> + f2fs_put_cache(entry, true); >> + continue; >> + } >> + /* >> + * at least there are shrinker, radix tree and another user >> + * has referenced the entry. >> + */ >> + if (f2fs_cache_refcount(entry) >= 3) { >> + f2fs_put_cache(entry, true); >> + continue; >> + } >> + >> + f2fs_do_truncate_cache(entry, false); >> + >> + if (f2fs_put_cache(entry, true)) >> + freed++; >> + } >> + >> + /* Phase 3: Splice un-reclaimed entries back onto cache->lru_list */ >> + if (!list_empty(&keep_list)) { >> + spin_lock(&cache->list_lock); >> + list_splice_tail(&keep_list, &cache->lru_list); >> + spin_unlock(&cache->list_lock); >> + } >> + >> + return freed; >> +} >> + >> +unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi, >> + unsigned long nr_to_scan) >> +{ >> + return f2fs_do_shrink_cache(META_CACHE(sbi), nr_to_scan); >> +} >> diff --git a/fs/f2fs/cache.h b/fs/f2fs/cache.h >> index 7ee98d276938..618b377590da 100644 >> --- a/fs/f2fs/cache.h >> +++ b/fs/f2fs/cache.h >> @@ -184,4 +184,7 @@ void f2fs_stop_cache_wb_thread(struct f2fs_sb_info *sbi); >> #define f2fs_truncate_meta_caches(sbi, start, len) \ >> f2fs_drop_cache_range(META_CACHE(sbi), start, len, true) >> >> +unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi, >> + unsigned long nr_to_scan); >> + >> #endif /* _LINUX_F2FS_CACHE_H */ >> diff --git a/fs/f2fs/shrinker.c b/fs/f2fs/shrinker.c >> index 4f6bf5926de4..1755c85849e4 100644 >> --- a/fs/f2fs/shrinker.c >> +++ b/fs/f2fs/shrinker.c >> @@ -37,6 +37,11 @@ static unsigned long __count_extent_cache(struct f2fs_sb_info *sbi, >> atomic_read(&eti->total_ext_node); >> } >> >> +static unsigned long __count_cache(struct f2fs_sb_info *sbi) >> +{ >> + return sbi->meta_blocks.num_entries; >> +} >> + >> unsigned long f2fs_shrink_count(struct shrinker *shrink, >> struct shrink_control *sc) >> { >> @@ -68,6 +73,9 @@ unsigned long f2fs_shrink_count(struct shrinker *shrink, >> /* count free nids cache entries */ >> count += __count_free_nids(sbi); >> >> + /* count generic cache entries */ >> + count += __count_cache(sbi); >> + >> spin_lock(&f2fs_list_lock); >> p = p->next; >> mutex_unlock(&sbi->umount_mutex); >> @@ -120,6 +128,10 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink, >> if (freed < nr) >> freed += f2fs_try_to_free_nids(sbi, nr - freed); >> >> + /* shrink generic cache entries */ >> + if (freed < nr) >> + freed += f2fs_shrink_cache(sbi, nr - freed); >> + >> spin_lock(&f2fs_list_lock); >> p = p->next; >> list_move_tail(&sbi->s_list, &f2fs_list); >> -- >> 2.49.0 >> >> >> >> _______________________________________________ >> Linux-f2fs-devel mailing list >> Linux-f2fs-devel@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel